West Australian mining practice; a description of the mining methods followed by the principal gold mines of Western Australia. With the assistance of the Publications Committee of the Chamber of Mines of Western Australia, inc

Cleland, E. Davenport · 1911 · Historical

14

Public-domain full text preserved in the Mountain Man Mining Library. Original source: archive.org.

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WEST A US TEA El AN MINING

Pe Ac Tice

Internet Archive "" in 2018 with funding from University of Toronto

://archive.org/details/westaustralianmiOOclel

A Description of tJie Mining Methods followed by the princi])nl Gold Mines of Western Australia

By

E. Davenport Cleland

With the Assistance of the Puhiicatioiis Committee of The Cliamber of Mines of AVestern Australia ( Incorporated)

With 14 Plates And 110 Illustrations

THE CHAhlHhi OF MIXES OF WESTERN AUSTRALIA (IxcnEPORATED)

KAI.GOORIME (W.A.) and LONDON

AH rights reserved

i’RiN'Ti-;i) i;v

E. S. IGG & SON I.Ti) .

Perth, W.A.

TfV

fl?G55

pin:FA( K

The articles tliat form the basis of the present Itook Tvei'e originally written for the Chamber of Mines by Mr. E. Davenport Cleland from information furnished by the mines, and they were published in the Journal of the Chamber of Mines dnring 1907 and 1908. Designed at first to give a description of mining methods on the leading mines of the State, the scope of the work has been widened dnring the process of revision, and in its present form the book may well be regarded as a text book on the mining practice of AVestern Australia.

Although every year sees alterations in detail and, with the advent of more efficient power generators and improved labour-saving devices, tlie cost of produc tion is gradually decreasing, the basic principles of mining practice undergo but little change. The practice of every mining field ]iossesses particular characteristics induced in |)art by the nature of the ore-l)odies and due partly to the influence exerted by the force of example in other and older fields. In Australia, at any rate, the older mining fields of Aictoria and New South AA'ales took their mining practice from the pioneer miners — mostly of Cornish origin — of the middle of last century, and the intluence of those founders of the industry in tiie new Continent is still evident.

In Western Australia, however, mining is of so recent date that no chain of precedents existed to exercise any restraint upon the development of mining practice. The engineers who came to the field in the early days of Coolgardie and Kalgooiiie came from every State in the Commonwealth and, indeed, from every mining country in the world. The accumulated experience of continents was at the disposal of the new field, and each man brought to bear upon his particular problem the experience gathered in many lands.

The experimental period is past and every mine has adopted those methods that experience has shown to yield the best results. On many points there needs must be diversity of opinion, and it is well that this should be, for all progress must cease when any particular method becomes recognised as the infallible standard. In this book no effort has been made to select the best practice; the actual methods

Preface

in vogue on the several mines are described, and the engineer who reads the book may choose from the many examples of varying practice the one best suited to his own requirements. For the benefit of the mining student, more space has been devoted to details of an elementary character than would usually be expected in a work of this description.

The Council of the Chamber of Mines wish to acknowledge their indebtedness to Mr. Chas. G. Gibson, B.E., late of the Government Geological Survey of Western Australia, who contributed the chapter on Geology, and to Mr. E. A. Mann, Chief Inspector of Explosives, for the chapter on Explosives. Their thanks are also due to the Institution of Civil Engineers for permission to reprint excerpts from Mr.

S. E. Palmer’s interesting paper on the Goldfields Water Supply. The Council also desire to express their appreciation of the interest and enthusiasm shown by the members of the Publications Committee of the Chamber in the preparation of the work and, in particular, the Eevision Committee, who devoted so much time to the recasting and expansion of the original articles now presented in book form. In this connexion they deem it fitting to make special mention of the work of Messrs. John A. Agnew, Lloyd Bloxsoine, A. L. Hay, F. G. T. Nicholas, G. Eidgway, J. Warrick and A. Wauchope, who placed their extensive knowledge of the West Australian mines at the disposal of the Committee, and, in no small degree, facilitated the whole process of revision. Grateful acknowledgment is due to those mine managers and officials who furnished the requisite data and rendered valuable assistance to the Author and the Committee.

Finally, the Council feel that this book may be regarded as a tribute to those men who laid the foundation of the mining industry in Western Australia, that industry, still of paramount importance, which raised the State from a i)osition of obscurity and furnished the waking community with means whereby to develop other natural resources equally rich, but undeveloped, until the mining industry brought in its train wealth and confidence, and a i)opulation strenuous and endowed with wider ideals.

’rilE SECEETAEY.

Kalgoorlie, W.xV.,

March 1, 1911.

Contents

. Chapter T

Geology

Kalg'oorlie — Leonora — Day Dawn

Chapter Ti

Shaft Sinking And Timbering

Vertical Shafts

Sizes of Shafts — Sinking — Boring out Shaft Bottoms — Stope Cut — Centre Ciit — Explosives and Firing — Removal of Broken Rock — Pent Houses — Shaft Timber ing — Square or Frame System — Description of Stage — Cost of Sinking . .

(Tiap'I’Er Hi

Shaft Sinking And Timbering

Underlay Or Incline Shafts

Sizes of Shafts — Sinking — Cost of Sinking

HEAD FRAMES, WINDING ENGINES, ROPES, AIR COMPRESSORS, ROCK-DRILLING MACHINES AND STEEL

Steel Frames — Wooden Frames — Sizes and Types of Winding Engines — Description of Hoisting Ropes — Air Compressors — Rock Drills — Drill Sharpening — Repairs to Machines

Chapter

Shaft Plats

Vertical Shafts — Underlay Shafts— Dimensions of Plats

Page

Contents

Chapter Vt

Mine Development

Distance between Levels — Crosscuts and Drives — Sampling — Boring and Firing — Winzes — Rises — Costs — Timbering Levels — Leading Slopes — Framed or Post-and- Cap Sets — Stull Timbering — Stull-and-Post — Saddle-back — Rafter Timbering . .

Chaptphi Yii

Ore Chutes And Passes

Construction — Dimensions — “Chinaman” Chute

Chapter \H[1 Stores And Storing

Methods of Sloping — Plat Back — Rill — Shrinkage — Costs — Relative Advantages and Disadvantages

C'lJAPTER IN

UNDERGROUND TRANSPORT OF ORE Truck Roads — Trucks — Ore Transportation — Plat Ore-bins

Ctl\Pter N

Cages, Skips, And Safety Appliances

Cages — Hinged Shoes — Side Safety Catches — Safety Hooks — Chains and Bearers — Skips — Gate for changing Cages — Cage Indicators

CHAPdTlR NI

SIGNALLING METHODS, APPARATUS AND CODES Knocker Line — Electric Signalling — Call Bell — Inter-level Signals — Signal Code . .

Chapter Nh

Ore Sampling, Weighing And Valuation

Page

Descriptions of Various I\Iethods employed

('ONTKNrS

CH APTF.n XT 1 1

J)lAiMOx\l) DRILLING

Particulars of Machines — Size of Core — Deflection of Pores — Costs

Chapter Xia

EXPLOSlVDaS

Composition — Purity — Chemical and Physical Exa)ninations — Safety Fuse — Fumes — Quantities and Value of Importations

CHAPTFAl XV

VEXTrLATKLX AND SANITATION

Ventilation and Sanitation

Chapter. X\'I

Mater Supply

Description of Government Water Supply — Pipe Line — Pumping iMachinery — Reser voirs and Reticulation — Cost

CHAPTER X\'n

UNDERGROUND WATER AND hllNE DRAINAGE Underground Water and hline Drainage . .

CHAPTER XVlil

Wages, Fuel, Transport And Administration

Page

Rates of AVages — Costs of Materials — Freight Rates — Alining Law

List of Plates

PliATE I.

„ Iii.

„ VI. „ Vll.

Geological Sketch Map of Kalgoorlie Great Fingall — Steel lattice-work head frame, do. Details for altering

do. Details of Junctions

Great Boulder — Tubular steel head frame — Edwards Shaft Associated Northern — Pyramidical wooden head frame Great Boulder — Gallows frame — Hamilton Shaft Lancefield — Oregon head frame do. Details of Junctions

X. do. Details of inclined structure XI. Sons of Gwalia — Head frame for incline shaft .. XII. do. Underlay shaft showing plat, ore-bin, etc.

,, XIII. Goldfields Water Supply — Locality Map, Section of Pipe Line and details of Valve Tower

,, XIV. Goldfields Water Supply — Details of Caulking Machine.

List of Iffi stratioxs

Fig. No. Tllostb.vtiox Page

1. Diagram showing “Stope-eiit” method used in Shaft Sinking .. .. .. 28

2. A Variation of the “Stope-cnt” in Shaft Sinking . . . . . . . . 30

3. Diagram showing position of the Holes in Vertieal Shaft . . . . . . 32

4. Shaft Timbering — Spaced Box System . . . . . . . . . . . . 35

5. Diagram showing method of direct hoisting in Shaft Sinking . . . . . . 37

6. Pentdionse with bearers, bed logs and angle-pieces of 12 x 12 in. timber . . 39

7. Pent-house with ventilation tine and safety door . . . . . . . . . . 41

8. Pent-house sliowing slight variation in detail of construction . . . . . . 42

9. Another type of Pent-house . . . . . . . . . . . . . . . . 44

10. Arrangement of bucket and traveller for raising broken rock from shaft, in

course of sinking . . . . . . . . . . . . . . 46

11. Shaft Timbering — detail of box system . . . . . . . . . . . . 47

12. Shaft Timbering — detail of box system . . . . . . . . . . . . 48

13. Shaft Timbering, showing detail of wall and end plates . . . . . . . . 49

14. Square or Pranie Set of Shaft Timbering . . . . . . . . 52

15. Shaft Timbering, showing method of wedging cage guides . . . . . . 54

16. Shaft Timbering — detail of joints and wedges . . . . . . . . . . 55

17. Square or Pranie Set of Shaft Timbering . . . . . . . . . . 58

18. Details of Underlay Shaft Timbers . . . . . . , . . . . . 64

19. Spirit Level, Template and Straight-edge used in adjusting Square-set Timbering

in Underlay Shaft . . . . . . . . . . . . . . . . 65

20. Diagram showing Turn in Shaft from Vertical to Underlay . . . . . . 69

21. Steel Lattice Work Head Frame — Great Fingall . . . . . . . . 71

22. Pyraniidical Head-frame constructed of local hardwood . . . . . . 72

23. Pyraniidical Head-frame showing method of increasing height . . . . . . 74

24. Vertical Winding Engine at the Great Boulder Mine . . . . . . . . 77

25. Steam Cross-compound Winding Engine with Patent Friction Clutches, etc. . . 79

26. Another Type of Winding Engine capable of hoisting from 4,000 feet . . . . 80

27. Air compressor of 3,000 cubic feet capacity per min. . . . . . . . . 84

28. Compressor of 3,000 cubic feet Air Capacity per min. . . . . . . . . 86

29. Tool-sharpening ]\Iaehine — Sons of Gwalia . . . . . . . . . . 87

30. Coke Furnace for Heating Steel for Machine Drills — Front Elevation . . . . 90

31. Coke Furnace for Heating Steel for Machine drills — End Elevation . . . . 91

32. Plat or Station — Vertical Shaft . . . . . . . . . . . . . . 94

List Of Illustrations

Rig. N'o. Illustration Page

33. Plat or Station — Underlay Shaft . . . . . . . . . . . . . . 95

34. Double and Single Plats serving Parallel Lodes . . . . . . . . . . 97

35. Crosscutting with Machine Drill . . . . . . . . . , . . . . 101

36. Showing hlaehine in Position for drilling . . . . . . . . . . 103

37. Showing Position of Holes in Pace of Drive. Rock of Average Hardness 104

38. Showing Position of Holes in Pace of Crosscut, kloderately Hard Rock . . 104

39. Showing iMethod of Placing Holes in Drives and Crosscuts in moderately

hard rock . . . . . . . . . . . . . . . . . . 105

40. Cro.ss Section of Crosscut, showing Position of Holes in Pace; Longitudinal Sec

tion of Crosscut, showing Pace Bored Out . . . . . . . . . . 106

41. Showing AYinze Sinking with Windlass and Bucket . . . . . . Ill

42. Winze Sinking with Air Hoist . . . . . . . . . . . . . . Ill

43. Self-Tipping Bucket for Winze Sinking . . . . . . . . . . . . 112

44. Showing Construction of Box Rise . . . . . . . . . . . . . . 116

45. Leading Stope . . . . . . . . . . . . . . . . . . . . 119

46. Timbering Level, Pramed or Post and Cap Sets . . . . . . . . . . 120

47. Timbering Levels, Frame or Post and Cap Sets . . . . . . . . . . 121

48. Complete Pramed or Post and Cap Sets, showing also Ore Chute and Double

Track in Level . . . . . . . . . . . . . . . . 122

49. Stull Timbers, showing Pole Lagging . . . . . . . . . . . . 123

50. Stull and Post Timbering . . . . . . . . . . . . . . . . 124

51. Saddle-back Timbering . . . . . . . . . . . . . . . . 125

52. Rafter Timbering, Showing Ore Chute and Trucks . . . . . . . . 126

53. Ore Pass and Chute . . . . . . . . . . . . . . . . . . 129

54. Ore Chute, Stull Timbers, and Pramed Set . . . . . . . . . . 130

55. “Chinaman” Ore Chute . . . . . . . . . . . . . . . . 133

56. Chute for Rough Ore . . . . . . . . . . . . . . . . . . 134

57. Chute for Rough Ore — In Snrinkage Stopes . . . . . . . . . . 135

58. IMethod of Stoping — Section Showing Rill Stopes . . . . . . . . 139

59. Diagram Showing Stope without Timber . . . . . . . . . . . . 141

60. Showing Truck and Temporary Tracks into Stope . . . . . . . . 143

61. Showing Construction of Pig-stys . . . . . . . . . . . . . . 146

62. Stage Scatfolding in Stope . . . . . . . , . . . . . . . . 147

63. Scaffolding Hook for Rock-drili staging . . . . . . . . . . 148

64. Scaffolding Hook for Rock-drill Staging . . . . . . . . . . . . 149

65. Pace of Stope Bored for Firing . . . . . . . . . . . . . 153

66. All-round Tipping Truck — Side Elevation . . . . . . . . . 161

67. All-round Tipping Truck — End Elevation . . . . . . . . . 162

68. All-ronnd Tipping Truck — Section thro-A.B. . . . . . . . . . . 162

69. All-round Tipping Truck — Door Showing Fastening . . . . . . . . 162

70. Cage Pitted with Hinged Shoes . . . . . . . . . . . . . . 165

71. Gig Used for Repairing and Timbering Shaft . . . . . . . . 165

72. Safety Grippers, with Lugs . . . . . . . . . . . . . . 165

73. Details of Double-deck Cage, showing Arrangement of Safety Catches . . 167

74. Safety Detaching Hook — first position. Showing Hook engaging with Collar 169

75. Safety Detaching Hook — second position. Showing Copper Rivet Sheared, and

Shackle Released . . . . . . . . . . . . . . . 169

f

LIST OF ILLUSTEATIONS xiii

Fig. No. Illustration Page

76. Safety Detaching' Hook — third position. Sliowing Projections engaging Avith

Collar to suspend Cage . . . . . . . . . . . : . . . . 169

77. Improved Chair, attached to Cage — Side .Elevation . . . . 170

78. Improved Chair, attached to Cage — End View . . . . . . . . . . 171

79. Improved Chair, attached to Cage — Plan . . . . . , . . . . 172

80. Illusti-ated Improved Chair attached to Cage, and Showing Braceman Drawing

out Bearers . . . . . . . . . . , . . , . . . . 173

81. Self-tipping Safety Skip — Elevation and End View . . . . . . 174

82. Self-tipping Safet.y Skip — Half Plan and Half Section . . . . . . . . 175

83. Self-tipping Safety Skip — Half Sections . . . . . . . . . . 175

84. Self -tipping Safety Skip — Hinge and Rest on Bottom of Skip. . . . . . 175

85. Self-tipping Safety Skip — Guide Shoes . . . . . . . . . . . . 175

86. Self-tipping Safety Skip — Safety Grips . . . . . . . . . . . . 175

87. Self-tipping Safety Skip — Locking Guide Attached to Skip Body . . 176

88. Self-tipping Safety Skip — Gear for operating Safety Gi’ips . . . . , . 176

89. Self-tipping Skip for Vertical and Incline Shaft . . . . , , 177

90. Self-tipping Skip for Vertical and Incline Shaft . . . . . . . . 178

91. Self-tipping Skip for Vertical and Incline Shaft . . . . . . . . . . 179

92. Self-tipping Skip in the act of discharging . . . . . , . . . . 180

93. Self-tipping Skip completely discharged . . . . . . . . . . 181

94. Swinging Gate for changing Cages . . . . . . . . . . . . . . 182

95. Swinging Gate for changing Cages . . . . . . . . . . . . 183

96. Signal Gong — Elevation . . . . . . . . . . . . . . . . 186

97. Signal Gong — Side Elevation . . . . . . . . . . . . . . . . 187

98. Signal Gong — Plan . . . . . . . . . . . . . . . . . . 189

99. Call Bell System — Diagram of Electric Signalling — Day Dawn Shaft, Great

Pingall Consolidated . . . . . . . . . . . . . . . . 190

100. Electric Signalling — Diagram of Electric Signalling System in use at the Great

Boulder Mine, Showing Arrangement of Pulls and Bells at various Levels 191

101. Details of Cast Iron Junction Box . . . . . . . . . . . . . . 192

102. Sullivan Diamond Drill on an Angle Hole 1.600 feet deep . . . . 203

103. Water Supply — Pipe Joints and Coating ... . . . . . . . . 236

104. AVater Supply — Pipe Joints and Coating . . . . . . . . . . 237

105. Abater Supply — Pipe Joints and Coating . . . . . . . . . . 237

106. AVater Supply — Locking-Bar and Plates . . . . . . . . . . . . 239

107. ALIter Supply — Caulking Machine . . . . . . . . . . . . . . 240

108. Miuidaring AAeir, Helena River . . . . . . . . . . . . . . 246

109. Ore Transportation — Tramway Feeding the Central Mill with Ore from the

Northern Mines at Lawlers . . . . . . . . . . . . . . 259

110. A iMode of transporting Stores from the Railway to Lawlers . . . . . . 260

a

Intiioduction

1[[STORICAr>

The first record of the discovery of minerals in Western Australia dates back to the year 1842, when copper and lead were found in the northern part of the State. Six years later appeared the first mention of gold and silver; traces of these metals were found in some specimens of copper ore sent to Adelaide for assay. The specimens came from the Murchison district, but the discovery appears to have aroused no interest, prospecting efforts having been entirely confined to the search for base metals and coal.

In 1852 the search for gold was initiated and several parties travelled east wards from York and Newcastle. Although they approached near to what is now known as the Yilgarn goldfield, their etforts were not attended any success.

During the next thirty-three years of the State’s history the interest in gold seeking increased, but no very tangible results reAvarded the search. It is true that in 1854 a party of prospectors, stimnlated by the offer of a reward for the discovery of payable gold, brought in gold-bearing specimens from Cardup, twenty-five miles from Fremantle. A small rush took place, but the only gold ever found in the district was that contained in the lu'ospectors’ samples.

From time to time, the shepherds in the country east of Northam brought in specimens of gold-bearing ore, and, in 1861, the snm of £2,500 was privately subscribed as a reward for any discovery of gold “within a radius of 150 miles of the Perth Post-office.” This sum was increased by a subsidy of equal amount from the Government. At the same time, the GoAmrnment engaged the serAuces of a prac tical miner from Noav South Wales, to examine the country from Albany to Northam, including the Darling Panges. His report was wholly unfavonrable.

A quartz lode was found in the yeai- 1873 near Albany, and a company aauis formed to Avork it. A battery was erected, but the lode proved to be valueless. In 1882 the first nugget Avas found; it Avas picked np by a horseman in the Cossack

liNTHOUUC'TlON

district. Tliis was followed by other discoveries, chiefly in the north-west, and these finds attracted the miners from the hlastern States, whose discoveries resulted in the Kimberley rush of 1886. The rush was short-lived; the natural diflicnlties were very great, and the results by no means justified either the hardships or tbe heavy ex])ense incurred. In 1887 the Yilgarn goldfield was discovered, and this field drew to itself the skilled prospectors of the north-west. The discovery of the Golden Valley — followed a few months later l)y the opening up of the Fraser’s mine at what is now known as Sonthern Cross — placed the mining industry on a lirm basis. During the succeeding years the tide of prospecting turned northwards again, and up to 1891 finds were made in the Pilbarra, Cue, Yalgoo, Nannine and Nid I agine districts.

It remained, liowever, for Bayley and Foi’d to inaugurate the era of real ])rosperity l)y their sensational discovery of Ooolgai'die in 1892. The rich alluvial that accompanied the gold-studded outcrop acted as a 7nagnet which drew the pick of Australian prospectors to the deserts of the West. In 1893 tliese hardy pioneers ])ushed out leyond Coolgardie, and that year saw the discovery of Kalgoorlie. liake Lefroy, Bardoc, Dundas, Goongarrie and Siberia. During 1893 Hannan’s alinvial find at Kalgoorlie employed 3,000 men, whose earnings were considerable. The rich discoveries of the Londonderry and the Wealth of Nations in 1894 gave a great impulse to prospecting work, and during that year almost every field now known on the Fastern Goldfields was opened up.

In 1895 the mines on what is now known as the “Golden Mile” began to show results, and in that year the Great Boulder and the Lake View entered the list of pro ducers. Ill 1896 the Fast Coolgnrdie Goldfield produced 268,411 line oz. of gold; this was almost doubled in the following year, and well nigh quadrupled in 1889. In 1903 the record outi)ut of 1,151,338 fine oz. was reached, and the grand total of the field to the end of 1910 was 12,345,673 fine oz., and of the whole State 23,077,600 fine oz. ITie dividends paid by the gold-mining com])anies in the whole of the State to the end of 1910 amounted to £21,351,403.

Chapter I

Geology

Kalgoorlie — Leonora — Day Dawn

Kalgoorlib

The importance of Kalgoorlie, which has l)eeii responsil)Ie for more than one half of the total gold yield of the State, renders some reference to its salient geological features necessary, hy way of preface to the subsequent chapters on mining practice, for experience in most inining fields of the globe has shown that many mining failures have been due rather to a want of knowledge, or true appre ciation, of structural geology, than to any lack of engineering training.

General Topography.— The chief topographical feature of the Kalgoorlie gold field is a main central ridge of hills trending roughly north -north-west and sonth- soiitli-east, and reaching its maximum altitude in hit. Gledden — better known as Mari- taiia Hill— which rises to a height of some one hundred and fifty feet; the ridge has a length of about four miles and dies out in a southerly direction just beyond the south end of what are known as the “Boulder Belt” mines. On each side of this central ridge are wide flats draining sontherlx' and extending laterally, on the eastern side for, say, five miles, and on the western for about three. On the east side of the eastern valley is another rather more cons])icnous ridge of hills also trending roughly north-west and south-east and having a maximnm altitude of ])ossibly a couple of hundred feet; along this ridge of hills are situated the mining centres of Boorara and AYaterfall (Golden Ridge). The western flats are also in tlieir turn flanked l)y a low ridge of hills, less conspicuous at their northern end but well defined at their southern. IhAh the eastern and western valleys — if they may be termed such — drain, as before stated, sontherly into the extensive salt lake or marsh known as (Kinm- balla or Hannan’s Lake, which starts but a short distance south, of tlie Boulder IMiues and trends away in a south and south-westerly direction for many miles. On the western side of this salt marsh and some three miles to the south of the Boulder mines is a small conspicnons clump of hills, having their highest point in Mt. Hunt, the most |)roniinent landmark in the district, which rises to a height of possibly some four hundred feet. These hills are more or less connected — by a westerly ex tension — to the main western ridge.

West Austealian Mining Practice

The town of Kalgoorlie is situated on the western fall of the main central ridge northwards from its middle point, and the mines are along the line of the ridge, the “Golden Mile” being at its southern end, the underlying rocks of the valleys be ing — as will be explained later — non-auriferous, or practically so.

General Geology. — The original rocks of the Kalgoorlie district were of sedi mentary origin, viz., shales, soft sandstones, grits, conglomerates, etc. — with possibly interbedded lava flows — laid down horizontally in probably pre-Cambrian time on a gneissic or granite floor; these were by earth movement afterwards tilted into their present highly inclined positions and subsequently intruded b)" large masses of basic and ultra-basic igneous rocks (amphibolites, quartz-diabases, porphyrites, perido- tites, etc.), these in turn being intruded by a small series of later acidic rocks (quartz and felspar porphyries). Slight further earth movement has then taken place caus ing considerable shearing and faulting of the rocks, the former (the shearing) re sulting in the formation of the lines along which the auriferous lodes of the field occur.

The accompanying geological map which embraces the main mining portion of the field shows the present relative extent and josition of the more important of the various classes of rocks found on the field. These may in a general way be grouped under the following nine heads; —

(1.) The Ancient Sediments (shales, sandstones, grits, conglomerates, etc.).

(2.) The Calc-schists.

(3.) The Fine-grained Amphibolites (representing the older “green stones”).

(4.) The Quartz-diabases.

(5.) The Coarse-grained Amphibolites (later or intrusive “greenstones”).

(6.) The Peridotites (intrusive ?).

(7.) The Porphyrites.

(8.) The Quartz and Felspar Porphyries (newer intrusives).

(9.) The Recent Deposits (sands, loam, laterite, etc.).

The Ancient Sediments. — These consist of shales, soft sandstones, mica and talc schists, grits and conglomerates. They are of very considerable extent and are found on both sides of the main complex of igneous rocks, the belt on the western side being of by far the greater development and interest. This belt starts some four miles west of Kalgoorlie and has a width of roughly ten or twelve miles, its general trend l)eing north-north-west and south-south-east; how far northerly it runs is not known, as everything is hidden in this direction by an extensive cover ing of loose sand and loam; southerly it is known to extend beyond Wollubar — some twenty miles from Kalgoorlie — but appears to be narrowing down in this direction and probably does not run much further. The rocks of this series are mostly soft banded sandstones, but they also comprise shales, mica-schists, grits and conglo merates; they have a prevailing strike of roughly 25 degrees west of north and dip steeply to the west. Good natural sections of these sediments can be seen along the small “breakaways” forming the western edge of the lake country some six miles south-west of Boulder; good examples — more especially of the sandstones — are also

WEST ArSTRALI' MINING PRACTICE

Geological Sketch Map

Kalgoorlie

C.G.Gisson B.E

lEXPLANATJON

JUcdC

ANCIENT 5EC5IMENTARV ROCKS CALC SCKISTS aM'

FINE GRAINED AMPHlBOLITtS 06— .

IHiZI

Coarse Grained Amphibolites . Popphywite ,

Felspar Porpkvhv I

Quartz Diabase.

PffllOOTiTE AND ITS DERIVATIVES aawv>

Geology

seen in some of the old mine workings near Binduli and in one or two old shafts on the eastern foot of the conglomerate ridge two to three miles further West — or rather south-west. An interesting variation from the soft sandstones is seen about a mile on the western side of this ridge and half a mile south of the Coolgardie road; here there is a considerable development of a hard compact laminated sand stone carrying a large percentage of black mica (biotite) in small flakes, and closely resembling in general appearance a fine-grained biotite gneiss.

The most interesting feature, however, in connection with these sedimentary rocks is the occurrence of a well-defined series of coarse conglomerates interbedded in the sandstones and grits. These have their greatest development at a point some eight and a half miles south-west of Kalgoorlie, where they form a well-marked ridge trending roughly north-north-west and south-south-east and extending for several miles both ways; this ridge is crossed near its north-western end by the main Coolgardie road at a point a little more than seven miles from the Kalgoorlie Post Office. There are at least three main bands of conglomerate in the series, and taken together with the intervening bands of soft sandstone, they have a maximum thick ness of well over a thousand feet. They are steeply inclined and dip with the en closing rocks, i.e., at an angle of seventy-five to eighty degrees to the west. The matrix of the conglomerate beds proper is a fairly soft, slightly micaceous sand stone, practically identical with the surrounding rock, while the pebbles and boulders — rarely more than six inches in diameter — consist of banded and jasperoid quartz, black cherty quartz, hard white quartz, quartzite, quartz and felspar por phyry, felsite, granite, etc. The pebbles,etc., are as a general rule set fairly closely together in the matrix and are well water- worn and rounded; they have, however, since their deposition been — together with the enclosing beds — subjected to con siderable pressure and shearing, and usually split fairly readily in one direction; were it not for this defect they would probably prove of considerable value for use as pulverisers in tube mills.

An interesting fact to note here is that in the neighbourhood of Mt. Squires, in the Warburton Range district, Mr. Frank Hann, the well-known bushman and explorer, has reported the occurrence of large bands of vertically-bedded conglome rates running for miles and forming a stee]) well-defined ridge of hills. This is the only similar occurrence that has been reported in Western Australia, and from Mr. Hann’s description and from seen specimens of the contained boulders, it is not improbable that these beds are similar to the Kalgoorlie (“Kiirrawang”) conglomerates, and, if so, it may be that other rocks in the district are also similar to those at Kalgoorlie, and that if a second “Golden Mile” is to be found this may he the district in which it is to he looked for, more especially as auriferous “greenstone” (amphibolite, etc.) country is known to occur in the Warburton dis trict.

On the eastern side of the main central Kalgoorlie ridge is a second series of sedimentary rocks, these occupy the valley between the Kalgoorlie and Boorara ridges and have a lateral extent of some three to four miles; the general trend of the belt is roughly north-west and south-east and it runs in these directions for a con siderable number of miles, its exact limits not being known. The rocks of this series — in keeping with all the others on the field — strike about thirty degrees west

West Australian Mining Practice

of north and dip steeply to the west; they consist for the most part of shales, soft sandstones and grits. A good section of what appears to be the western edge of the series can be seen in the old Phoenix brick pits just on the southern side of the KanoAvna road and about two miles from the Kalgoorlie Post Office.

A third series of sedimentary rocks is also found on the eastern side of the Boorara ridge, extending from Knrramia almost to Kano wna, or roughly four miles; this belt also runs a])])roximately north-west and south-east, and the rocks are very similar to those of the Bindnli-Kurrawang — or western — series, viz., soft sandstones, grits, and conglomerates; they strike in the prevailing north-north-west to north west direction, and as usual dip steeply to the west. The conglomerates of this series differ from those of the western in tliat tliey are of much less extent and not so well delined; the lieds are also iimch more weathered. A section showing the conglomerate bed can be seen in a small cutting about a mile and a half along the Knrramia wood line; the band is here about a hundred feet thick and is interbedded with soft sandstones; the jielibles and boulders are mostly of hard blue quartz with quartz and felsiiar porphyries — the latter being greatly weathered.

All the sedimentary rocks of the district are, for all practical purposes, non- auriferous, and therefore of no great economic importance.

The Calc-schists. — These, as can be seen from the map, form the eastern por tion of the main auriferous series and, next to the (piartz-di abases, are the most important series on the field. The rocks are essentially tine-grained, but vary some what in colour and general appearance; typically they are dark grey on fresh fracture with a someAvhat blotcliy appearance, and are characterised by uumerons minute veins of calcite running throngh them in all directions; they break readily in almost any direction and frecpiently show a slight development of scaly chlorite along the cleavage planes — Avhen these are present. A less typical type is darker, finer grained, more coinpact, harder and does not exhibit the same amount of schistosity ; it is merely a less sheared and less altered form; this type differs but little in hand speci mens from some of the finer-grained chloritic diabases.

Those rocks were probably originally a basic lava flow, possil)ly at one time interbedded Avith the sedimentary series; owing to the extreme alteration that has taken place in them their original structure has been almost completely obliterated, and they now consist essentially of an indefinite mixture of chlorite and carbonates, with only occasionally traces of their original crystalline form left; in addition to the chlorite and carbonates microscopic iuAestigation shows the following minerals to be present in small quantities; — sericite, albite, zoisite, quartz, ilnienite, rutile and iron ores.

In their original form the interlacing and interlocking of the original mineral fibres and crystals would give a certain degree of toughness to these rocks, but, ow ing to the almost total obliteration of this structure by replacement of the original minerals by finely crystalline and non-crystalline carlmnates, this toughness has been destroyed and the rocks fracture readily, and this fact, together with their general comparatiAm softness, makes mining ojAerations in them comparatively easy and cheap; moreoAmr, OAviug to the less fretpient occurrence of joint planes and “heads” this class of country after opening up stands much better than much of the quartz-diabase and amphibolite country.

Geology

The Fine-grained Amphibolites. — These are found on the western side of the northern portion of the coarse-grained amphibolite, at Somerville, about two miles along the Coolgardie road, and also on the eastern side of the calc-schist belt; portions of these areas are shown on the accompanying map. In places they very closely resemble the rocks of the calc-schist series and with them probably belong — in the main — to an older series of “greenstones,” being possibly a closely related lava flow or intrusion.

Typically, the rocks of this series are of a dark green colour, mostly massive, and very fine-grained; they consist apparently almost entirely of light-green horn blende and chlorite with occasionally small crystals of felspar. A microscopic ex amination of them shows their constituent minerals, in a typical specimen, in addi tion to the hornblende, chlorite and felspars to be calcite, epidote and various iron ores; in some specimens the horn))lende has entirely disappeared and is replaced by greenish chlorite. As far as known this series is to all intents and purposes non- auriferous and therefore of no great economic ini])ortance.

The Quartz Diabases. — The series of rocks to which the name “quartz-diabase” has been given is by far the most im])ortant on the Kalgoorlie goldfield, as it is with in them that nearly all the lulnciijal ore-bodies at present being worked are found.

The rocks vary greatly in general ai)pearance according to the amount of foliation, shearing and chemical alteration that they have undergone. The type rock is massive and fairly coarse-grained; it has a mottled ai)pearance, being dark-green in general colour with white porphyritic fels]uirs — or what were originally felspars — and occasional fair-sized blebs of colourless quartz, a good deal of this probably being of secondary origin. Under the microscope the rock is seen to consist essen tially of plagioclase felspar, quartz and chlorite, the quartz and felspar frequently showing micro-pegmatitic structure, while the chlorite probably represents the re mains of original angite; in addition there are present ilmenite (largely altered to leiicoxene), calcite, apatite, and saussurite.

Another variety is much finer grained with — in hand specimens — no sign of porphyritic felspars, and with the quartz blebs developed to a much less degree; on microscopic examination, however, this rock proves to be only a modification of the previous one. Both these types are found massive and are also found subjected to all degrees of foliation, schistosity and chemical alteration.

The quartz-diabases are as a series very closely allied to some of the coarse acid amphibolites and in all probability were originally derived from tlie same magma.

Several interesting forms of extreme alteration are found in the diabases, one of the chief ones being the occurrence of the so-called “graphitic-slate” bands. These are of fairly common occurrence and are sometimes found up to well over a hundred feet in thickness, the more usual width being two to six feet; they are frequently of considerable ])ersistence in strike and have been known to occur down to a vertical depth of well over two thousand feet; they are also known on the other hand to extend only a comparatively few feet both longitudinally and verti cally. In places these so-called “slates” exhibit a very marked and regular fissility and in hand specimens exactly resemble true sedimentary slates or shales. The pre sent reference is too short to permit of a close investigation in detail of the question.

West Australian Mining Practice

but a careful examination of the bands leads to the conclusion that they are merely hig’hly - sheared bands of country rock, the graphite being deposited subsequent to the sliearing, and being probably formed as the result of the decomposition of hydrocar])ons derived from deep-seated sources. The bands are occasionally closely associated with the ore-bodies and in these cases, owing to the graphitic material becoming mechanically mixed with the ore, they cause some annoyance to the metallurgist.

In many instances the hands are non-graphitic, and in these cases they still more closely resemble true slates, especially nearer the surface, where they are slightly weathered; occasionally slight secondary silicification has gone on and the bands then closely resemble fine-grained phyllites. They likewise occur in the calc-schists, in both the coarse and fine-grained amphibolites, and also to a less extent in the porpliyrites.

The second interesting modification occurs as tlie result of the extreme car bonating of the rocks, whereby they are converted into a mixture of lime, iron and magnesium-carbonates, together with a certain amount of original and some secondary quartz. This form of alteration is extremely cominon and often occurs over con siderable widths — 150 feet and more; it is — as is to be expected — most marked where the shearing of the rocks is most pronounced, and in almost all cases is fonnd to occur to a greater or less degree in the immediate proximity of the lodes; fre quently it can be noticed taking place on both sides of a main fault-line or cleav age-plane, the carbonating being most intense near the fault — or cleavage — and gradnally dying out on both sides until the rock reaches its normal state. In its extreme form the carbonated rock is white to pale pink on fresh fracture, but it very rapidly changes on exposure to a dull pink owing to the oxidation of the fer rous carbonate present; in texture it varies from a fine-grained compact variety with very little quartz to a coarse variety with large quartz blebs, this latter variety when seen by candle light underground having at first glance very much the general appearance of a pink granite or syenite. All gradations can of course be obtained from the coarse carbonated type to the typical diabase. A highly schistose variety of the carbonated rock is sometimes found along the lode-channels or where secondary shearing has taken place; this is usually creamy-white in colour and has a somewhat greasy appearance and feel, owing to the large development of seri- cite along the cleavage-planes; in some of its forms this sericite-carbonate schist is locally known as “fish rock.” Splendid examples of this carbonating of the diabase are to he seen in certain of the deeper workings of the Lake View, the Perseverance and the Ivanhoe mines — in fact in almost all the workings within this class of rocks. In the Ivanhoe mine towards the end of the main west crosscut at the 1,669-ft. level is to be seen a splendid example of the various changes from the normal green mottled diabase to the coarse white to pink carbonated type.

For exactly the same reasons as with the calc-schists, mining operations in the carbonated diabases are easier and cheaper than in the normal rock; along the same crosscut very often can be seen cuts that have been fired in both classes of rock; in the carbonated variety the cuts will be shot out right to the extreme end of — and even slightly beyond — the holes, while in the tougher normal rock often as much as eight or nine inches of the hole will be left in the face.

Geology

In addition to the main fault-lines — which will be referred to later — the dia bases are crossed by numerous small secondary faults, fissures and cleavages ; these dip at all angles and run in all directions, though the prevailing strike of them is roughly at right angles to the strike of the main faults, and they are probably in most cases induced fissures caused by pressure along these main lines; they are found crossing the lodes as well as the country, but as a rule do no harm beyond the fact that by their intersection with each other or with well-developed shear-lines, they sometimes cause considerable falls of rock to take place in the stopes and — to a less extent — in the drives.

The Coarse-grained Amphibolites. — These are really of two types, {a) the basic and (b) the felspathic or acid; they are, however, for all practical purposes inseparable, and the latter variety is simply an acid variation of the former, occur ring as a fringe on the western side of the northern area, the change from one to the other being a gradual one. Typically, the felspathic variety is a coarse-grained green and white mottled rock — coarser grained than the typical quartz-diabase — showing large irregular crystals and blebs of felspar intermixed with dark-green crystals of hornblende and chlorite; the two being present in apparently approxi mately equal proportion; frequently a little clear quartz is also present. In some of its varieties this acid type very closely resembles some of the quartz-diabases, the two, as before stated, being probably originally derived from the same magma.

The basic type — which is found at both the north and south ends of the field — is in hand specimens a dark-green coarse-grained rock consisting apparently al most entirely of green hornblende and chlorite.

The rocks of both types are generally massive and have not been, on the whole, subjected to the same amount of shearing and alteration as the diabases — though sheared areas do occur, especially to the north-eastern end and in the neighbourhood of Hannan’s Hill.

In economic importance certain of the acid amphibolites rank next to the calc-schists, but it is practically only at the north end that they contain any auri ferous deposits of commercial value, and even these are of no great importance when compared with those in the diabases. On their western and southern extensions the amphibolites, both basic and felspathic, are practically non-auriferous; the pre sence of auriferous lodes at the north end may be to a large extent due to the pre sence of intrusive igneous rocks (peridotites and porphyries) in the neighbourhood.

Coarse-grained amphibolites — principally of the basic variety— occur over a large area to the south of the Boulder Belt in the neighbourhood of Mt. Hunt, and also in the hills forming the ridge further west; these, however, are outside the scope of the present chapter; sufficient is it to say that they also are for commercial purposes practically non-auriferous.

The Peridotites. — These have their greatest development at the south end of the field along the western edge of Hannan’s Lake towards Mt. Hunt, this area be ing beyond the limits of the accompanying map (Plate I). Several smaller areas of what is apparently a carbonated peridotite occur, however, at the north end of the field and the positions of these are shown on the map.

AVEST AUSTRAIJAN AvIINING PRACTICE

The i)ericlotite at the south end of the held is almost black in colour, is very hne-grained, breaking Avith a somewhat conchoidal fracture; it has suffered con siderable alteration and in some cases has been altered into a solid serpentine rock. On a small island on the Avest side of the lake it has, l)y the action of carbonated waters, been entirely coiiAmrted into a dark-grey coarsely-crystalline rock composed chiehy of cai'bonates of magnesia, iron and lime.

A little asbestos (var. jhcrolite) is found here and there in the peridotites, but it is of no great commercial Amine; scattei-ed over the hills, hoAvever, are here and there fair-sized patelies of magnesite (carbonate of magnesium) Avhich might possibly be put to some use as furnace linings, etc.

The rock at the north end of the held, Avhich has been mapped as a deriva tive of the ))eridotite, is a gi-eyish, fairly coarsely crystalline, carbonated rock, agreeing almost absolutely in analysis Avith that found at the edge of Hannan’s Imke. It is found to be iiiAmriably associated with the fuchsite (chrome mica) l)earing lodes so cons])icuous at the northeiai end of the held, and it is i)robably the soui'ce fi-oni Avhieh the fuchsite has lieen derived, as it is found on analysis to con tain a little oAmi' one half ])er cent, of cbromi(‘ oxide. Especially good examples of these fuchsite lodes can be seen in the Hidden Secret, Fair])lay and Devon Consols leases. Exce])t for their close relationship to ceidain gold-bearing lodes at the north end of the held, the peridotites themselves can be classed as non-auriferous.

The Pot ))hy) lies. — These are of very considerable extent and for the most part are found underlying the recent deposits of the hats on the Avest side of the Kalgoorlie ridge and to the south and south-west of Boulder. Typically they are inassiAm, and of a Iwownish-green to dark-l)rown ground colour with numerous white porphyritic crystals of felspar and occasionally dark porphyritic hornblende cry stals; the microsco])e shows these i)or])hyritic felspars and hornl)lende to be set in a slightly greenish very hnely crystalline felsitic ground mass, the greenish colouration being dne to the i)resence of a little hnely-diAuded chlorite. Numerous variations fi-om the ty])e si)ecimen occur; one of these is a very hne-grained dark- grey eonii)act variety shoAving in hand specimens no trace of poiphyritic structure, while only a feAA" feet aAvay the rock is mottled in a})pearance and shoAvs innumer able large Avhite [)orphyritic felspars set in a dark grey-green to brown ground mass; in this latter type are frequently noticed patches up to two inches in diameter of a pale-grey felsitic-looking material; these represent merely more acid portions Avhich have segicgated out from the original molten mass on cooling. (Ather varia tions, which ])rol)ably represent segregation on a larger scale, a])proach \mry closely in general ai)pearance to quartz and fels])ai- ])orphyries. Still another variation is seen on (told Mining Lease 1,928, about three miles south of Boulder Block (Fimiston); here can be seen on a dunq) a very dark almost lack rock of fairly hne texture shoAA'ing a large develo])nient of biotite in small hakes and crystals; it is a biotite-porphyrite and, as far as can l)e seen, merely a local Amriation from the general type.

The por])hyrites occur as large masses — as shown on the map — and also in the form of small dykes; these latter are found traversing the amphibolites in all directions, but are neAmr at any great distance from the main mass, from Avhich they are eAudently only off-shoots.

Geology

Sheared examples of the porphyrites oeeur and in tliis form it very closely resembles, when weathered, some of the soft sandstones of the sedimentary series, so innch so in fact that it is })ractically impossible to distingnish between the two in hand specimens. At Mommient Hill, on a western arm of Hannan’s Lake and some three-and-a-half miles sonth-sonth-west of Boulder Block, is an example of sheared and weathered por])hyrite exactly i-esembling the sediments of the Knrrawang series ; several shafts sunk on it have lu'oved its nature beyond dispute. At Wal she’s (narry, about a mile along the Coolgardie road, are ex])osed a series of rocks whose origin is more donl)tfiil; as seen in the face of the qiiariy these rocks apijear to consist of sandstones, soft siliceous slates and shales; they ))iay be of sedimentary origin, l)nt a careful comparison of them with other rocks of the held, strongly sn])ports the o])inion that they are merely sheared and weathered porphyrite.

While on the subject of the porphyrites mention must be made of the ‘‘build ing stone” so much used in Kalgoorlie some years ago for Imilding })urposes. This is in its typical form a light-coloured fairly compact, rather line-grained rock, soft enough to lie cut with a knife and closely resembling in general ap})earauce a soft sandstone; it freciuently exhil)its a red-and-white or brown-and-white l)anded appear ance, this being due to original horizontal weathering of the rock, ddie greater por tion of tliis stone used in the past has been olhained from the White Cliffs — or Button’s — ({uarry, some three miles south-west of Boulder Block; in this case it is simply a mncli-weathered porphyrite. A very similar class of rock results from the weathering of the massive amphibolites, but not much of this has l)een used for building purposes.

The porphyrites are as a whole non-auriferous.

The Quartz and Felspar Porphyries. — These are found for the most part in the form of narrow dykes intruding the older rocks of the field; they are not numerous and are of no great imi)ortance; the felspar-] ior})hyries are the more common type; they are as a rule hard and compact, usually of a piidGsh colour and have a very line-grained felsitic ground-mass, in which are embedded fair-sized por])hyritic crystals of felspar.

They form dykes of from ten to forty feet in width and often of considerable length, good examples of which can be seen in the workings of the Hainanlt, South Kalgurli, Perseverance, Ijake Tew and other mines. These dykes have in many cases been subjected to much shearing and have suffered the same faultings, etc., as the main lodes; they ap])ear to have been intruded ])rior to the formation of the majority of the lodes and, as far as can be judged, do not seem to have had any marked influence on the deposition of the gold.

A large extent of coarse felspar and quartz pori)hyry is found in the vicinity of Binduli; here there are two well-defined parallel bands up to a maximum of twenty chains in width, running for several miles in a north-westerly and south easterly direction. This occurrence is of interest principally on account of the ])resence of large crush breccias at both the southern and northern ends of the main band. The finest of these breccias is seen at the south end, some four miles from the Coolgardie road; here it extends over a width of from ten to twelve chains —

West Australian Mining Practice

the full width of the porphyry— having in a general way much the appearance of a compact coarse boulder conglomerate and being in every way similar to the so-called conglomerates of Kanowna, which seem to be nothing more or less than similar crush Ijreccias; by following it in a north-westerly direction it can be seen to pass gradually into, first, a slightly sheared, and finally, into the unaltered porphyry. This breccia has been formed by shearing of the porphyry while it was still probably in a more or less semi-molten condition. The second similar breccia towards the north end of the band cannot be seen on the surface, but it has been exposed in the workings on G.M.L. 3,645, a mile-and-a-half to two miles north-west of Binduli.

A similar class of breccia is found within the main porphyrite area, on Water Right 221 about three-quarters of a mile north of Lakeside; here some of the boulders are up to nearly two feet in diameter. No outcrop of this breccia can be seen, but it has been opened up to a considerable extent by mine workings which are now unfortunately inaccessible.

The Recent Deposits. — These consist of loose sand, loam, ironstone-gravel, etc., and are the result of the gradual weathering and breaking down in situ of the underlying rocks. They cover by far the greater part of the district, often to a consideral)le depth, and make accurate geological mapping at times a matter of almost practical impossibility, and what is probably of more commercial import ance, they also render surface prospecting extremely difficult.

Included in these “recent deposits’” are the laterites, or ironstone-conglomer ates, which are such a conspicuous feature of the district. The question of the exact origin of these laterites has at times given rise to considerable argument and even to the present time has not been altogether satisfactorily settled; the fairly commonly accepted belief is that they have been formed in situ by the gradual concentration by atmospheric agencies of ferric oxide derived from the decompo sition of the underlying rocks, which in every case have been originally rich in iron com])ouuds. These recent deposits have not been shown on the map, which claims only to show the main structural formations.

The Ore Deposits. — The class of deposit worked on the Kalgoorlie field is that to which the term “lode deposit” has been generally applied, for though in a few cases quartz reefs of small size have been opened out, these are always more er less intimately connected with the main class. These lodes have in a general way been well defined as —

“More or less vertical zones of rock usually continuous with the surrounding country and of similar origin, but distinct from it in carrying metallic ores disseminated through them, often in payable quantities, and frequently characterised by strong foliation. They owe their existence to a shearing and faulting action having crushed and foliated portion of the main rock mass in a certain definite direction, producing a more or less well-defined band of rock through which, by virtue of the foliation, mineral-bearing solutions can have free circulation. In con sequence of this, mineral deposits are formed within the rock, usually, but not necessarily, extending over the whole of the foliated zone and having no definite boundaries horizontally or vertically other than those determined by the decrease of assay values to a point at which they cease to pay working expenses.”

Geology

For the purposes of detailed description the ore-deposits are best grouped according to the various classes of rock in which they are found, viz.; —

(1.) Deposits in the quartz-diabases.

(2.) Deposits in the calc-schists.

(3.) Deposits in the acid amphibolites.

(1.) The Deposits in the Quartz-diabases. — These may be subdivided into: — (a.) The quartzose ore-bodies.

(b.) The schistose or carbonated ore-bodies.

There is however no hard and fast line between the two classes, both being of the same origin and each in i)art grading imperceptibly into the other. x4s a general rule, however, the quartzose bodies are more regular both in values and occurrence than the carbonated. Typical bodies of this class are those worked in the western group of mines, viz., the Great Boulder, Horse-Shoe and Ivanhoe; most of the other mines are on carbonated or schistose bodies.

The essential difference between the two classes lies in the fact that a greater amount of replacement has taken place in the former and the original lode-material has been to a large extent gradually replaced by a dark compact cherty-looking quartz, while in the latter the alteration is chiefly to carbonates; these ore-bodies always have a more or less banded appearance and the development of the quartzose material is always greater in the central portion of the lode. Within the limits of the lode-channels are frequently found small irregular veins of white glassy quartz, usually running at right angles to the strike of the lodes ; these rarely carry any appreciable gold values, hut very often contain considerable amounts of tourmaline and tennantite (sulpharsenide of copper) in addition to the usual vein minerals; they are of very limited extent, rarely extending for more than a few feet in any one direction, and are evidently of secondary origin, probably marking shrinkage cracks in the lodes proper.

Very frequently the main lodes show signs of secondary movement and of re opening, especially along the centre line of fissuring; in these cases the middle por tion of the lode is much brecciated, the darker original quartz being broken up and re-cemented by a fine-grained intergrowth of white quartz and calcite. This re opening is also seen in the case of the carbonated lodes, though the re-cementing of the brecciated material is not so noticeable as in the darker quartzose bodies.

In the case of the carbonated lodes their general appearance varies from a more or less solid mixture of carbonates to a very slightly carbonated sericite or chlorite schist; they are much more irregular both in size and in the distribution of the values than the quartzose lodes.

Almost invariably the main central line of the lodes is marked by a small well-defined seam, usually of quartz with carbonates of iron, etc., and generally not more than a quarter of an inch in width ; this represents the central line along which the original shearing has taken place, and it can be followed in many cases for long distances; often the lode, i.e., the crushed and altered rock, will die out and this central seam then exists merely as a narrow cleavage running through the comparatively solid country.

Avest Aestrallan Aiining Practice

]L>

Aliiieralisation of the lodes has of course taken place to the largest extent where the foliation and crushing have been most intense, while in the more solid rock it has taken })lace only over a very small area extending outwards from the main iissure. As the shearing of the rocks is irregular in its intensity, so also is the ex tent of the mineralised lodes irregular, the occurrences Ijeing to a certain extent lenticular; in some cases — where the shearing has l)een fairly general — the mineralisa tion has extended over a widtli of well over a hundred feet and the whole of this width has carried payable gold values, while at other times along the same lode line the shearing — and mineralisation — is coiihned to a width of a few feet; in short, wherever the country has been highly foliated or sheared, there mineralisation has taken place, but in these mineralised hands, though gold is invariably present up to a certain extent, it is not always there in sufficient quantity to pay for working.

Along the main lode-lines in many cases the values are found to occur in ir regular lenticular xiatches even where there is ap])arently no change in the lode; in other cases the more highly sheared portions throughout which the ores are de})Osited are themselves lenticular in habit, and as these lenses are irregular both in size and occurrence they cause some slight trouble both in mining oxerations and in the satisfactory estimation of ore reserves; for example, a level may be driven for some distance on good values, while one stoxje taken above the drive may see the end of these values; this has actually ha])X)ened on more than one occasion. Again, in X'l'ospecting for ore-hodies with the diamond drill, this lenticular habit of the lodes is ax)t to l)e very misleading owing to the fact that a hore-hole might cut an ax>l>arently fair-sized body of ore which on further develoxnnent will xi’ove to be only an isolated lens of no great length or dexth; at the same time it would be equally likely to miss a lens of ore and cut the lode where it had pinched or carried no values.

The lode-channels themselves are very xei’sistent both in strike and in dexth and have been frequently known to continue without a lu'eak through several leases; the length and frequency of the ore-lenses along the same lode vary greatly; while one lens may he sevei'al hundred feet in length tlie next one may be only twenty feet; frequently however, the uersistence in dex)th of the short lenses is just as great as with the longer ones, though this is not always the case; all the lenses as a rule show a tendency to x’itc'h to the south. The values never cut out entirely along the main lodes, but in those })ortions of them connecting two ore-lenses they dro]i to a ])oint at which they cease to be at present xayable.

All these mineralised shear-zones, or lodes, have a roughly xai’allel strike, this being axqn’oximately north-north-west, and as they are fairly numerous, exten sive diamond-drilling or cross-cutting has to l)e resorted to in order to xrove their existence; frequently a low-grade lode will he intersected in a crosscut and a good deal of develoximent work has often to he carried out along it in the chance of meet ing with a lens of xayable ore, these being of xassible occurrence along any lode channel.

AA'ith regard to the mineralisation of the ore-bodies the xrincixal lode minerals in addition to gold and tellurides (calaverite, xetzite, sylvanite, hessite, coloradoite, altaite) are iron xyEtes, marcasite, chalcoxyrite, tennantite, asbolite, carbonates (of iron, lime, magnesia, etc.), sulx3hates (of lime and magnesia), iron ores (hema-

Geology

tite, magnetite, ilmenite, etc.), tourmaline, chlorite, albite, rutile, etc. Of these the most important is — next to the gold and tellnrides — the iron pyrites; this is usually present in fair quantit.y, and it is invariabl.y found to he the case that the hner-grained it is the higher are its gold contents; frequently a coarse more or less crys talline pyrites is present, more especially on the wails and in the carbonated lodes, and this almost invariably carries no i)ayahle values ; it has apparently been deposited at a later date and certainly under different conditions from those of the finer-grained auriferous ])yrites.

(2.) The Deposits in. the Calc-schists. — No quartzose ore-bodies occur in this series of rocks, the lodes being similar, and l)ehaving similarly in every way, to the schistose or carbonated ores found in the diabases, and the same general re marks apply almost equally well to both. As a general rule, however, they are more patchy in their contents and on the whole of lower grade than the latter class of deposits.

Special, though brief, mention must, however, l)e made of one particular ore- body occnring within the calc-schists, and this is the remarkable “Oroya shoot.’’ The ore-hody in this case was in the form of a pipe or chimney whose cross- section, though irregular, approximated in a general way to a more or less flattened oval having in places a maxinmm diameter of roughly a hundred feet. The general pitch of the “pipe” was at a very flat angle to the south, with, at the same time, an underlay to the west. Tt lias been worked from the surface down through the following leases: — Brown Hill, Iron Duke, Oroya and Australia East, or for a total length of over three-quarters of a mile; at the point where it a])pears to have died out it had reached a vertical de})th of about twelve hundred feet. Immediately on the east side of the iiipe is a well-defined body of highly-sheared rock dipping at an angle of forty-five to fifty degrees to the west; the ore aiqiears to have lain on or close to this shear-line, dipping with it and at the same time ])itching away, as before stated, very flatly to the south. In several places the hanging and foot walls — if they may he termed such — of the ore-hody are formed by well-marked fault or fissure-lines, and these, taken in conjunction with the main underlying shear plane, have probably had a good deal to do with the deposition of the values. Occasional small patches — or “drop]iers” — of ore run out from the main body; these are of very limited extent and are generally formed on an intersecting cleavage or fissure-plane.

(3.) The Deposits in the Acid Amphibolites. — Lodes similar in origin and general character to those in the diabases and calc-schists also occur iu certain of the acid amphibolites, but they have not as a general rule so far jn’oved of any very great importance.

The main point of difference between this class of rocks and the diabases and calc-schists is the occurrence witliin them of small rich quartz veins and leaders. These have been worked to the greatest extent iu Hannan’s Reward and on Cassidy Hill; they are never of any great size, rarely exceeding a foot in thick ness and more usually ranging from a mere thread up to only two inches; they are confined to certain well-defined belts of sheared rock and are never found beyond the limits of the sheared zone, running at rigid angles to the general trend of this: although consequently never of any great length, they are fairly ])ersistent in dei)th.

Avest Australian Mining Practice

In the big lode on Hannan’s Reward, which near the surface exceeds a hundred feet in thickness, these leaders were especially numerous and some of them were ihienomenally rich. At first merely the leaders themselves were taken out, hut sub sequently the whole lode-formation — which itself carried a little gold — was worked, the high-grade of the quartz veins being sufficient to bring the grade of the whole formation up to payable Ihnits. It is from these quartz leaders that the bulk of the alluvial gold obtained in the neighbourhood of Hannan’s Hill was originally derived.

Another class of deposits found in the amphibolites of the north end are the contact bodies referred to previously as occurring alongside the peridotite dykes. These are merely mineralised zones of sheared and altered rock, and must be classed as “lodes;” they are however irregular, following to a considerable ex tent the boundaries of the peridotite ; they are also of comparatively small size and their gold contents are very erratic, although at times extremely high. They are characterised as a rule by their l)right-green colour, this being due to the presence of finely divided fuchsite, whose occurrence has already been referred to. Lodes of this description are typically represented in the Hidden Secret and Fairplay mines.

AUhile on the subject of the lodes generally, brief mention must be made of the large banded and jasperoid quartz reefs occurring in certain portions of the field. These are found principally in the amphibolites, and especially at the south end in the neighbourhood of Mt. Hunt. They are of dark banded and jasperoid quartz, often carrying a large percentage of hematite and sometimes magnetite, and are the result of extreme alteration and silicification of well-defined sheared bands of rock; they are very persistent in strike, sometimes extending for over a mile in length and are of large size, occasionally reaching as much as fifty feet in width; near Mt. Hunt they are particularly numerous and can be seen in places rising from the ground to a height of 40 or 50 feet. Although small auriferous quartz leaders are at times associated with them, the jasperoid lodes themselves appear to be practically non-auriferous.

The Faults. — Faulting of the lodes has been fairly common, more especially in the quartz-diabase and calc-schists areas; the main system runs approximately parallel to the general strike of the lodes and the faults dip at an angle of 40 to 45 degrees to the west. The faults of this system are “reversed” faults, and are due to overthrusting of the western portion of the belt ; contrary to the usually accepted idea of reverse faults, they do not duplicate the lodes. Occasionally, however, normal or easterly-dipping faults do occur, but they are much less usual than those with a westerly dip. The displacement caused by both classes of faults varies con siderably, usually, however, ranging from ten to forty feet. As a general rule the faults of the main system are very persistent not only in strike but also in dip, and can readily be followed down from level to level; they are usually marked by a seam of calcite or gypsum, or a “dig,” varying from half an inch up to as much as four inches in width, and in the latter cases almost always act as water channels. Occasionally values are found along the fault-lines between the two portions of the lode; these sometimes extend over a width of as much as two feet; but, as a general rule, values are not found in appreciable quantity along the fault-lines.

Geology

The numerous small fissures, or “heads” or “floors,” which are found cros sing the lodes and country in almost every direction, but chiefly at right angles to the main lines, are evidently part of a secondary system induced by these main lines; as a general rule they cause no displacement.

The chief effect of the main faults is, by their presence, to lessen the apparent amount of ore “in sight” between any two levels by causing, as a result of the over thrusting upwards of the upper portion, the formation of a vertical — as well as horizontal — gap between the two portions of the faulted lode.

Another effect of the faulting is represented by the following occurrence which actually took place in the Great Boulder Main Reef mine. An inclined bore- liole from the No. 14 level cut what appeared to be two separate ore-bodies; sub sequent development, however, proved the supposed second body to be merely the faulted portion of the original one, the bore-hole thus having jiassed through the same lode twice; equally well also might it have passed through the gap between the two portions and thus have apparently proved the non-existence of the lode below the level bored from.

Conclusion. — With regard to the permanency of the Kalgoorlie and Boulder lodes it may be at once stated that they are undoubtedly deep-seated and will in every probability live at least to the depth to which mining operations can at pre sent be carried; whether or no their gold contents will live with them is a matter on which it is impossible to speak with any certainty, and one which can only be proved by actual development; the best arguments in favour of this, however, are the following deep-level developments reported by two of the leading mines of the field: —

Golden Horse-Shoe. — Cabled Report to London, May 19th, 1909: “No. 3 shaft, 2,000-feet level — East branch. No. 3 lode, total width 18 feet, assays 1 oz. 2 dwt. per ton; free gold and telluride showing from wall to wall.”

Great Botdder Proprietary. — Cabled report to London, August 25th, 1909 : Prospecting with diamond drill, Edwards’ shaft, 2,600-feet level, IVest — At 108 feet from shaft struck ore, for the first three feet schist intermixed with quartz leaders, the ore is very rich in free gold; assays average 11 oz. per ton. The next three feet similar, but there is no visible gold, assays average 5 dwt. per ton. The next 8 feet consists of pyrites and quartz, assay value 5 dwt. per ton; there is quartz in the end of the bore-hole.

Cabled report to London, November ]2th, 1909 : Edwards’ shaft, 2,500-feet level — West crosscut has cut the reef 98 feet from shaft; it is hard quartz; width of ore 14 feet, and assays lOMj dwt. per ton,

Cal)led report to London, December 11th, 1909 : Edwards’ shaft, 2,500-feet level — North end of drive, average assays 15 dwt. ler ton; south end, 44 . per ton.

These developments are the deepest on the field and speak for themselves as to the permanency of the lodes and their values.

Since the foregoing was written, consideral)le petrological work has l)een carried out in connection with the Kalgoorlie rocks, and the result has confirmed

West Australian Mining Practice

tlie view that the so-called “newer greenstones” all belong to one main intrusive series, consisting originally of plagioclase-angite and (jnartz-])lagioclase-angite rocks of the gahbro or diabase t5'pe.

The two main groupings that have l)een adopted in this chapter have been made for economic reasons and for simplicity in map])ing rather than for strictly technical ]mr])oses. The distinguishing feature of tlie groups is the relative amount of mass alteration that has taken place in each, this alteration being represented chiefly by the partial or complete molecular change of the original augite in the rocks to hornblende, uralite, and chlorite.

In the case of the so-called “quartz-diabases” molecular alteration — probably largely assisted by the ]U’esence of the intrusive ])0]'])hyries — has proceeded to a niucli greater extent than in the “ amphi1)olites, ” the original augite being wliolly and completely altered to cldorite. Tlie term “(piartz-diahase” has lieen given to these chloritic rocks in order to distinguish them from the less-altered and less- auriferous rocks, because this is what they a])}iear to have lieen originally.

The “ coai'se-grained amphibolites” comprise all the varions modifications of the original newer greenstones, exclusive of the above chloritic (“quartz-diabase”) type, viz., gabbros, ]iy]-oxenites, amphibolites, etc. Ty]iical gabbros are not found within the limits of the map imblished herewith (Plate I), Imt are confined to that area of greenstones referred to in the text as the western ridge, and lying immediately behind the Kalgoorlie abattoirs. The “felspathic amphibolites,” however, which are found at lioth the north and south ends of the central area, are derived from the gabbros, through the change of the original augite to horn blende and uralite. All gradations between the two classes are obtainable in the field. A more correct subdivision of the amphil)olites referred to in the article, viz.

(a) the liasic, and (b) the felspathic or acid, ivoiild be (a) the quartzose or acid

(b) the felspathic and (c) the basic. "Ihiese Ijave their greatest develo]nnent over the northern ai'ea and are undoubtedly merely differentiations from the one intrusive mass; the quartzose or more siliceous type occupies, as would be expected, tlie central liortion of the mass and gradually merges on lioth sides into the more basic varieties forming the outer margins, the “basic” being on the eastern, and the “felspathic” on the western margin. The “quartzose” type was i)robably originally a quartz- galibro, a slightly acid segregation from the normal type; the “basic” was (in liart) a ]yroxenite, being a basic segregation from tlie original mass, while the “fels]iathic” ]u-obably re]iresents the nearly normal rod-: (gahbro or, in part, dialiase). In the case of the “feis|)athic” type the cliange of the oiaginal augite has lieen to hornblende and uralite; in the “basic” it lias been (largely) to hornblende; and in the “(piartzose” it has gone further to uralite and chlorite. 'I''his latter ty]ie approaches very closely to the “quartz-diabase” stules. but the (‘hange of the augite to chlorite has not been (piite as conqilete :is in that series.

The important facts, howeel, in connexion with the various modi (ications and alterations of these original gabbros, etc., are as follow; —

(t) The rocks in which the conversion to chlorite of the original augite has been conqilete, viz., the “quartz-diabase” series, are those which, contain all the highly-auriferous lodes.

Geology

(2.) The rocks in which this conversion to chlorite lias been partial, viz., the chlorite “quartzose, or acid, amphibolites” of the north end, contain certain less highly anriferons lodes.

(3) The rocks in which there has been practically no conversion to chlorite, viz., the typical amphibolites, gabbros, etc., of the western group, contain no auriferous lodes.

From these facts it appears not unreasonable to assume that the gold has originally been held in combination by the ferro-magnesian mineral (augite) and the splittting up of this — to chlorite, etc. — has ]irobably assisted in the liberation and solution of the gold subsequently deposited in the lode formations. That this is so, or that the conditions atfecting the conversion of the ferro-magnesian minerals had any connection with those affecting the deposition of the gold is, of course, open to argument, but the fact remains that in the wholly cliloritic rocks, and in them alone, are the highly- auriferous lodes to be found.

In the earlier portion of this chapter dealing with the felspar-porphyry dykes, it is stated that “ ... as far as can be judged, they do not seem to have

had any marked influence on the deposition of the gold;” this statement was intended to infer more that they had no immediate effect on the local enrichment of the lodes — which they have not — rather than that they had nothing to do with the general process of mineralisation, etc. As a matter of fact they have probably had a great deal to do with the mineralisation, etc., of the older lodes, in so far that the presence of magmatic water following on their intrusion has been the direct cause of, or, at least, has largely assisted in, such mineralisation.

In this context the term “ auriferous ” is meant to imply a f;rade of ore that mav be profitablv mined.

West Australian Mining Practice

Geological Sketch Map Of Kalgooelie

Index To Leases

Registered Name of Lease.

Registered No. of Lease.

Name of Leaseholder.

Acrobat

392e .

Pariuga IMines Ltd.

Adelaide

lOlE .

Associated G.Ms. of W.A. Ltd.

Alice

1,307e

Golden Horse-Shoe Estates Co. Ltd.

A1 .

±,38oe

Privately oAvned.

Auckland

1,17.5e . .

Brown Hill Extended Ltd.

Australia

38e . . . . )

Australia North

71e . . . . 1

Associated G.Ms. of W.A. Ltd.

Australia East

72e . . . . J

A.W.A. United .

4,051e

Privately oAvned.

Bank of England

33e

The New North Boulder G.Ms. Ltd.

Birthday Reef

34e . . . . 1

Birthday South

22e . . . . )

Kalgurli Gold Mines Ltd.

Blue Cap

24e

Central and West Boulder G.Ms. Ltd.

Bonnie Lass

796e

Privately owned.

Bonnie Play

4,088e

Privately OAvned.

Bonnie Scotland

4,326e

Privately oAvned.

Boomerang

890e .

Privately owned.

Boulder Consols . .

888e

Central and West Boulder G.Ms. Ltd.

Boulder Consols West

4,366e

Great Boulder Proprietary G.Ms. Ltd.

Boulder Extended

4,363e

Privately owned.

Brilliant

1,653e

Hannan ’s EeAvard Ltd.

Britannia

302e

CrcESus South G.Ms. Ltd.

Britannia No. 1

301e .

Oroya Links Ltd.

Brown Hill

698e

Oroya Links Ltd.

Brown Hill Consols No. 2

4,356e

BroAYu Hill Consols Ltd.

Brown Hill Extended

o58e

Brown Hill Extended Ltd.

Brown Hill South

3,961e

BroAvn Hill Extended Ltd.

Brown Hill North

989e .

Croesus South G.Ms. Ltd.

Brown Hill Junction

l,10lE

Privately oAvned.

Cassidy Hill .

4e

Paringa Mines Ltd.

Cassidy’s North . .

1,163e

Privately OAvned.

Chaffers

352e .

Chaffers G.M. Co. Ltd.

Chaffers South

4,334e

Chaffers G.M. Co. Ltd.

Chaffers Extended

1,116e

Hannans Star Consolidated Ltd.

Chaffers Parallel

4,365e

PrivEMtely owned.

Comstock

4,3.51e .

Privately owned.

Comstock North

4,361e .

Privately owned.

Confidence

4,307e .

Privately OAvned.

Crescent

1,357e . . . . 1

Crescent Extended

1,412e . .

Ivanhoe Gold Corporation Ltd.

Crescent North

1,413e . . . .

Croesus

739e .

Oroya Links Ltd.

Croesus Consols

269e .

Oroya Links Ltd.

Croesus North, No. 1

238e .

Croesus North No. 1 Ltd.

Cygnet .

944e .

Oroya Links Ltd.

Darkan

4,368e .

PrNateh' OAATied.

Devon Consols

3,880e .

Westralian Machinerv Corporation Ltd.

Devon Consols Consolidated

4,146e .

Westralian Machinery Corjioration Ltd.

Devon Consols South Extended

4,037e .

Privately OAvned.

Eagle Hawk United

3,770£ . .

Privately owned.

Eclipse

750e

Orova Links Ltd.

Ethel .

1,001E .

Golden Horse-Shoe Estates Co. Ltd.

Euclid

4,054e .

Privately owned.

Eureka

35e

The New North Boulder G.Ms. Ltd.

Eureka East

975e

The New North Boulder G.Ms. Ltd.

Pair Play

4,052e . .

Privately owned.

Geology

INDEX TO LEASES (continued)

Registered Name of Lease.

Registered No. of Lease.

Name of Leaseholder.

Fair Play Extended

4,063e .

Privately owned.

Federal

743e .

Oroya Links Ltd.

Gem

4,331e .

Privatelv owned.

Genevieve

444e .

North Kalgoorlie Co. Ltd.

Gilberton

4,226e .

Hannans Proprietary Ltd.

Golden Collar

3,612e .

South Kalgoorlie G.Ms. Ltd.

Golden Gate

281e .

North Kalgoorlie G.M. Ltd.

Golden Link

2,326e .

Lake View Consols Ltd.

Golden Leveret

902e .

Hannans Star Consolidated Ltd.

Golden Pike

1,294e .

Golden Pike and Lake View East G.Ms. Ltd.

Golden Spur

1,1 13e .

Golden Horse-Shoe Estates Co. Ltd.

Golden Zone

1,694e .

Privately owned.

Good Luck

794e

Oroya Links Ltd.

Great Boulder

16e .

Great Boulder Prop. G.M. Ltd

Great Boulder South

oIe

Great Boulder Prop. G.M. Ltd

Great Boulder North

102e .

Great Boulder Prop. G.M. Ltd

Great Secret

4,124e .

Privately owned.

Great Golden Lead

4,397e . .

Privatelv owned.

Great Scott

1,002e .

Golden Horse-Shoe Estates Co. Ltd.

Grand Junction

1,109e .

Great Boulder Prop. G.M. Ltd

Great Boulder No. 1 South

1,08.5e . .

Golden Horse-Shoe Estates Co. Ltd.

Great Boulder No. 2 South

1,219e .

Golden Horse-Shoe Estates Co. Ltd.

Great Boulder No. 3 South

1,326e .

Golden Horse-Shoe Estates Co. Ltd.

Great Boulder East

25e

Lake View Consols Ltd.

Great Boulder East Extended . .

2,32.5e .

Lake View Consols Ltd.

Great Boulder Extended

oOe

Great Boulder No. 1 Ltd.

Great Boulder South Extended

873e

Chaffers G.M. Co. Ltd.

Great Boulder and Lake View Deposit

986e

Hannans Star Consolidated Ltd.

Haiuault

3,643e .

Hainault G.Ms. Ltd.

Hannans Consols

14 C.E. . .

Privately owned.

Find .

4,0o6e . .

Privately owned.

Hill .

97e

Hannans Eeward Ltd.

., North

4,274e . .

Privately owned.

,, North, No. 2 . .

4,380e .

Privatelv owned.

Eeward

160e .

Hannans Reward Ltd,

., Star Extended

4.358E .

Privately owned.

Hidden Secret

4,001e .

Privately owned.

,, North

4,03.5e .

Privately owned.

,, South

4,036e .

Privately owned.

„ „ West

4,107e .

Privately owned.

Hird ’s Lease

3,991e .

Privately owned.

Homeward Bound

4,2.56e .

Privately owned.

Horseshoe Extended

4,386f, .

Privatelv owned.

Horseshoe Parallel

4,400e . .

Privately owned.

Idaho

4,317e . .

Privately owned.

Idaho Extended

4,318e .

Privatelv owned.

Iron King

73e

Oroya Links Ltd.

Iron Duke

49e

Associated Northern Blocks (W.A.) Ltd.

Ironsides North . .

946e .

Privately owned.

Isabel G.M.L.

983e

Privatelv owned.

Ivanhoe

31e

Ivanhoe Gold Corporation Ltd.

Ivanhoe Junction

1,507 k . .

Ivanhoe Gold Corijoration Ltd.

Ivanhoe Soutli

351e . ,

Golden Horse-Shoe Estates (ki. Ltd.

Ivanhoe Venture

4,397e .

Privatelv owned.

Ivanhoe West

61e

Great Boulder Prop. G.!Ms. Ltd.

Ivy .

4,320e . .

Privately owned.

Jubilee

448e . .

Oroya Links Ltd.

Kalgoorlie Golden Eagle

1,004e . .

Privately owned.

Lake View

32e

Lake View Consols Ltd.

Lake View Consols

923e

Hannans Star Consolidated Ltd.

Lake View Consols

1.196e . .

Hannans Star Consolidated Ltd.

Lake View South . .

75e

Lake View South IJd.

Lake View East . .

4.362e . . . . :

Golden Pike and Lake View East G.Ms. Ltd

Lady Elizabeth

415e

Privately owned.

20 West Australian Mining Practice

INDEX TO LEASES (continued)

Registered Name of Lease.

Registered No. of Lease.

Name of Leaseholder.

La Maseotte

4,.399e .

Privately owned.

Little Fair Play

4,3 19e .

Privately owned.

Little Wonder

4,346e .

Privately owned.

Lily .

4,301e .

Lily G.Ms., No Liability.

Lone Hand

4,345e . .

Privately owned.

Lord Nolan

4,3.59e .

Privately owned.

Lucknow

4,103e .

Privately owned.

Mannajone

4,302e .

Privately owned.

Maritana

2e

Maritana G.Ms. Co., No Liability.

Maritana

279e

Maritana G.Ms. Co., No Liability.

Mathoura

1,621e .

Orova Links Ltd.

Machinery Lease

M.L. 2e

Kalgoorlie Gold Recovery Co. Ltd.

Machinery Lease

M.L. 5e

Brown Hill Consols Ltd.

Milanese

4,293e .

Privately owned.

Mount Fern

4,337e .

Privately owned.

Mt. Charlotte

211e .

Hannans Reward Ltd.

Mt. Charlotte

212e .

Hannans Reward Ltd.

Mt. Charlotte

213e .

Hannans Reward Ltd.

Mt. Ferrum Consols

4,320e .

Privately owned.

Mt. Ferrum West

4,281e .

Privately owned.

Mt. Ferrum West Extended

4,371e .

Privately owned.

Mystery

4,347e .

Privately owned.

Napoleon

4,025e . .

Privately owned.

New Eeefers

4,284e .

Privately owned.

Off Chance

4,277e .

Privately owned.

Old Mortality

280e

Great Boulder Prop. G.Ms. Ltd.

Oroya

410e .

Oroya Links Ltd.

Oroya East

4,221e .

Associated Northern Blocks (W.A.) Ltd.

Pearce ’s Prospecting Party

287e

North Kalgoorlie Co., Ltd.

Perseverance

66e

Great Boulder Perseverance Co. Ltd.

Poseidon

4,309e .

Privately owned.

Princess Louise

1,395e . .

Oroya Links Ltd.

Queen of the West

4,225e . .

Hannans Prop. Ltd.

Red, White and Blue

1,228e .

Privately owned.

Revell Cross South

949e .

Central and West Boulder G.Ms. Ltd.

Residence Lease

R.L. 2e

Hannans Prop. Ltd.

Royal Mint West

532e

Oroya Links Ltd.

Royal Gold Mine

4,121e .

Privately owned.

Rising Sun

4,039e .

Privately owned.

Sheba

4,367e . .

Privately owned.

Sons of Gwalia, Kalgoorlie

3,771e .

Privately owned.

South Kalgurli . .

1,208e .

South Kalgurli G.Ms. Ltd.

Star

4,273e .

Privately owned.

Star of the East Extended

4,075e . .

Hannans Star Consolidated Ltd.

Star of the East South . .

1,124e .

Hannans Star Consolidated Ltd.

Successful

4,224e .

Hannans Prop. Ltd.

Sun God

4,231e .

Privately owned.

Tailings I.ease

T.L. lE

Great Boulder Prop. G.Ms. Ltd.

Talisman

4,360e .

Privately owned.

True Blue

578e

Oroya Links Ltd.

True Blue West

969e .

Oroya Links Ltd.

Trurant

4.187E .

Privately owned.

Trafalgar

3,031e .

Oroya Links Ltd.

Trafalgar South . .

4,180e .

Oroya Links Ltd.

Union Club

4,289e .

Privately owned.

Union Jack

535e . .

Privately owned.

Wandin

4,383e .

Privately owned.

Water Lease

16e

Ivanhoe Gold Corporation Ltd.

Willoughby

4,409e . .

Privately owned.

Willoughby West

4,410e .

Privately owned.

Young Mt. Morgan

6e

Oroya Links Ltd.

Young Mt. Morgan Extended . .

131e .

Oroya Links Ltd.

(No Name)

15e .

Hannans Star Consolidated Ltd.

(No Name)

60e .

Hannans Star Consolidated Ltd.

(lEOLOGY

Leonora

The following brief notes on the districts of Leonora and Day Dawn are com piled from the official publications of the Geological Survey Department and not from the author’s personal knowledge of the districts.

Topographical. — Approaching Leonora from the south the general appearance is that of a long ridge of more or less pointed hills extending roughly north-west and south-east and having a maximum altitude of about two hundred and fifty feet. On the west side of this ridge are wide fiats extending with an im- jDerceptible slope to the eastern side of the Lake Raeside salt-marsh, which stretches in a north-westerly and south-easterly direction for at least a hundred miles and of which the deepest parts are occupied by salt water pools and then dried up salt and gypsum beds. The country to the east, though largely occupied by flats, is rather more broken.

The district forms portion of the eastern watershed of Lake Raeside, the divide between this and the Lake Carey drainage area being approximately twelve miles to the east, while in a westerly direction, at a distance of from four to five miles, the country begins to fall towards the Lake Barlee basin.

Geology. — Broadly speaking the district may be geologically defined as an area of crystalline schists, of which by far the greater portion is covered by recent superficial and alluvial deposits. The rocks fall naturally into two main divisions: (a) the greenstones and {b) the granitic rocks.

The group of rocks comprising both massive and schistose forms to which the general term greenstone has been applied, have by far the greatest economic importance of any in the district. This formation must be regarded as a single area of basic rocks which has been more or less crushed, foliated, or completely con verted into schists, the latter structure being on the whole the most usual, and to such schistose zones the auriferous reefs are almost entirely confined. An examina tion of the district enables the “greenstone schists” to be separated from the mas sive and foliated variety, and also permits of the recognition of more than one variety of basic or ultra-basic rock, but the exact geological relationship of the several varieties is not determinable.

The Greenstones. — The greenstone schists are most largely developed on the outer margins of the main belt in juxtaposition to the granitic rocks, while the middle portion is occupied more or less by massive rocks. Those on the western side contain nearly all the important ore bodies. On the eastern side of the belt the greenstone is found in an extremely high state of metamorphism ; there is here a considerable development of the remarkable banded and hematite-bearing quartz which forms one of the most noticeable features of the district; outcrops of this banded quartz are found in the form of lenses from ten to fifty chains in length and from one foot to a hundred feet in thickness; they follow the general strike and dip of the schists and are merely altered and silicified bands of schist; with one or two exceptions they are iDractically non-auriferous.

The Granitic Rocks. — As with the greenstones so also the granitic rocks are divided into (a) massive and foliated varieties and {h) a completely schistose variety; both types are found, however, at times to grade one into the other. The

(a) Geol. Survej', W.A. Bulletin No. 13. Leonora, by C. F. V. Jackson, 1904.

West Australian Mining Practice

massive aud crushed rock in which the original granitic structure can be recognised lies on the west, forming as it were a buttress against which has been thrust the moi-e schistose country to the east. This eastern country is distinguished from that on the west by tlie original form of the rocks being in no case recognisable, and also by the extent to which the rocks have ))een affected by the agencies of decomposi tion.

The Ore Deposits. — With the above separation of the rocks the ore deposits fall naturally into four classes according to the class of country in which they occur; there is, however, a similarity throughout in a lenticular habit and particularly in the tendency of the lodes to follow the planes of foliation of the containing rock.

For the purpose of this article the only class of deposit dealt with will be that worked in the Sons of Gwalia mine.

The ore-body here occurs entirely in the greenstone schists, and is made up of numerous mineralised quartz veins of varying size and distinctly lenticular habit. These quartz veins have been developed over a zone of considerable width, the rock itself being also impregnated with minerals containing gold; the actual lateral ex tent of this lode formation however, except on the east where it is limited by a tabular mass of less crushed rock, (‘annot 1)0 accurately detined; the general course of the lode is 16 degrees east of north and its average di]) 45 degrees to the east. iM ining operations havek) been entirely conlined within the formation to three lenses or shoots of ])ay-ore, of sueh size and iu such ])osition as to be workable by a separate system of stopes, and in each of which the mineralised veins are so closely assoeiated as to form more or less parallel ore bodies of compact quartz. Each zone of highest value within the shoots composed of an aggregate of the quartz veins, appears itself to have assumed a somewhat lenticular form, having a core or lens of more highly mineralised quartzose material from one to two feet in thickness and extending laterally from 20 to 60 feet — a “lens of ore.”

A numl)er of these lenses connected by a chain of values follow each other roughly in the same plane, and, together with the inq>regnated formation containing them giving a total stoping width of from six to thirty feet, have made up the ore bodies of the mine. Owing to their development to a greater or less extent through- oiit the whole of the lode and the fact that only a certain series of them carry the payuil)le values the actual course of the shoot can only be followed by an elaborate and careful system of sampling.

Day

The mining centre of Day Dawn is situated on a large alluvial flat — or valley — flanked on either side by a low range of hills, that to the westward being the highest and by far the roughest.

Geologically considered, the whole area may be classed as greenstone with its usual schistose and altered varieties. This general term greenstone has been used to include not only the usual hornblende schists and amphibolites, but also the diorites, diabases and andesites, all of which are found in the district. The amphi bolite and its altered forms — chlorite schists, etc. — occupies all the eastern and southern portion, and also underlies the large alluvial flat, whilst the diorites and epidiorites occupy the north-western hilly portion.

(61 Recent observations tend to show that many of these so-called granitic schists may be schistose quartzites or quartz-schists of sedimentary origin, (c) In 1904. (rf> Geol. Survey, W.A, Bulletin No. 29. Day Dawn, by H. Woodward, 1907.

Geology

The amphibolites are highly foliated and altered near the surface, the cleav age planes running in a general north and south direction, except in the contact zones where there is considerable variation due to local shearing. Near the surface these rocks are represented by brown greasy clay schists passing into chlorite schists and hornblende rocks at a depth.

The igneous rocks are usually massive at the surface, exhibiting but little sign of foliation.

Acidic porphyry dykes are frequently met with penetrating the basic igneous series and are in all probability off-shoots from the main grano-diorite mass lying to the west.

The ore-bodies of the district are in every instance of the normal type of quartz reef, presenting the usual characteristics of zonal enrichment which may either occur as a well-defined shoot following the folds in the plane of the fissure, or as patches near the surface, of limited extent but great richness. The reefs for the most part lie in a series of more or less parallel lines along the centre of the area, having with one or two exceptions a general northerly trend with a dip to the west ward; the fissures along which they have been formed represent as a rule fault or shear planes. Many of these quartz reefs are found to have well-defined outcrops traceable at the surface for a considerable distance, whilst upon development at lower levels they are often found to consist of a series of lenticular masses; in other cases there are isolated outcrops following a general line of strike, and these latter may possibly be found to be one continuous body at a depth; in both instances their formation is due to the unequal opening of the fissure.

The reefs of the district can be divided into three main groups: (1) those in the igneous zone, (2) those in the contact zone and (3) those in the amphibolite zone.

In the igneous area the reefs appear to occupy faulted fissures which have a general trend north and south and a dip to the westward; they often bifurcate and are not so regular in their course as those met with in the more foliated country, neither are the quartz bodies of such length, though the fissures may be of consider able extent.

The second group contains all the principal productive mines of the district; the reefs, generally speaking, have a decidedly more north-westerly course than the preceding and underlie to the south-west; one main point worthy of note with regard to the zone of greatest enrichment in this group of mines is that this occurs in the reefs at a point which varies from ten to fifteen chains from the boundary of the igneous rocks, whilst in the reefs having a normal course the shoot dips towards them.

The third group in the amphibolite area is of the usual normal type, posses sing a general northerly strike and a westerly dip. So far, the reefs of this group, though of fair size and extent, have not proved of any very great importance.

In the case of the Great Fingall mine, the most important mine in the district, the reef lies within — or more correctly across — the contact zone, its course starting from the south end being first west-north-west, then north-west, then north-north west until it branches, the western branch following a course a little west of north

West Australian Mining Practice

and the eastern a slightly more easterly conrse. The average dip of the vein is 60 degrees and the general character of the outcropping quartz is a dense blue grey or blackish banded stone, while the enclosing country varies from a brownish highly-weathered schist to chlorite schist and epidote rock, which at the northern end is replaced by a massive hornblende rock.

Below the surface the lode presents all the characteristics of a faulted fis sure, being possessed of good walls often stricted and polished, and being often separated from the adjacent country rock by a thin seam of clay — or ‘‘dig.” In places, large masses of rock have become detached from the walls and subsequently enclosed in the lode matter, thus forming “horses,” while at other times vughs or cavities lined with quartz crystals are met with in the vein itself.

In the sulphide zone the quartz carries in addition to gold, small quantities of pyrites, pyrrhotite, arsenical pyrites, blend, galena and chalcopyrite.

Throughout the main shoot the reef for a considerable length runs to a width of from thirty to forty feet; at the ends, however, it pinches away to mere stringers and threads beyond which nothing hut the fissure line remains.

The pay-ore occurs in limited but defined sections, or shoots, of considerable size separated by zones of poorer or barren ground; these shoots do not follow the lissure-plane down upon its full dip, but traverse it diagonally more to the north ward; they occur at the points where the vein attains its maximum proportions

West Australian Mining Practice

CHAP'l'ER II

Shaft Sinking And Timbering

Vertical Shafts

ciizes ot Shafts — Sinking — Boring Out Shaft Bottoms — -Stope Cut — Centre Cut — Explosives and Firing — Eemoval of Broken Eock — Pent Houses — Shaft Timbering — Square or Frame System — Description of Stage — Cost of Sinking.

The information given on this subject is confined to the sinking of shafts by means of machine-drills operated by compressed air. The costs quoted are those incurred in sinking through hard rock at varying depths down to 2,000 feet. In the early days of the Kalgoorlie field innumerable shafts were sunk for pros pecting purposes, and while passing through the zone of decomposed rocks to depths averaging 150 feet, good progress was obtained by hand-drilling ; the hoisting of rock was done by windlass, horse-whip, or small steam hoist. Immediately below the decomposed zone, however, the rock hardened rapidly, and the desire of the mine- owners to hasten the development of their properties made it necessary that air- compressors and machine-drills should he introduced. The sites of the main shafts on the various mines have been determined mainly by the pitch of the shoots of ore as disclosed by the original prospecting shafts. As a rule, they are conveniently placed for the economical handling of ore, and the distribution of timber and stores to the various levels. On the Kalgoorlie field all the main shafts are vertical. Else where on the goldfields a few incline shafts have been sunk ; these will be dealt with subsequently.

Sizes of Shafts. — The earliest indications of the ore deposits at Kalgoorlie were not such as to lead to the belief that bodies of very considerable size would ultimately be developed. From their nature and condition, which differed materially from the well-defined quartz reefs commonly met with in the other Australian States, many mining engineers and scientists had grave doubts as to the likelihood of the lodes penetrating the sulphide zone or living to any considerable depth therein, and, consequently, it was thought that the cost of sinking large and convenient main shafts was not justified, and mine managers were content with those of a moderate or even small size. As a consequence, the majority of the main shafts on the field appear to be small in comparison to the monthly tonnage of ore required to be hoisted. In addition to this, the shafts are used for the raising and lowering of men at change of shift, the handling of timber and stores of every description, and the hoisting of waste rock derived from shaft sinking, or from development work on the various levels. The dimensions, inside timbers, of the

2b

West Australian Wining Practice

earlier shafts range from 10 by 4 ft. up to 11 ft. 8 iu. by 4 ft. (i in. Shafts of later date range from 13 ft. 6 in. by 4 ft. 6 in. up to 14 ft. by 5 ft. 6 in. In all instances the shaft is divided into three compartments, though iu a few isolated cases the , or ladder-way, compartment has been subdivided to form an auxiliary hoist ing- way as well as a compartment for air and water pipes, etc. A summary of dimensions would be as follows: —

ijeiigth of shaft (inside timbers) tVidth of shaft (iusitle timbers)

Number of hoisting compartments Length of hoisting compartments Lengtli of pump and ladder-way compartments

10 to 14 ft.

4 ft. to 5 ft. 6 in.

Two

3 ft. to 4 ft. 6 in.

3 ft. 8 iu. to 5 ft. 8 in.

Sinking’. — Under this head is comprised the time spent in lowering tools and men into the shaft; hxing or rigging-up of the machine drills; boring out of the shaft bottom and taking down machines; hoisting of machines, tools and men; in charging and tiring the holes, cleaning up the broken rock, and, when required, sending down shaft timber and putting it in place in the shaft. Consequently, the quotation of the average depth advanced per month includes the completion of the shaft throughout, with the exception of putting in the cage-guides in the hoisting compartments and the ladders, etc., in the third compartment. The time and cost of cutting plats or stations at stated levels are not included. Plat-cutting will be dealt with subsequently. The si)eed of sinking is, to a very large extent, governed by the fact that in the great majority of instances, the hoisting of ore for mill supplies has to proceed with as few interruptions as possible. The blasting and removal of rock from the shaft Ijottom lias, therefore, to be arranged so as not to interfere with the hoisting of ore. AVith few exceiitions, the main shafts on the Kalgoorlie mines are placed with their length parallel to the line or strike of the lodes, which is approximately north and south. They have not, therefore, so great a degree of strength to resist the thrust or movement of the strata inclining on the one side, as a shaft would have if sunk at right angles to the strike of the country; but, owing to the nature of the rock met with, no serious trouble has been experienced from movement or ]iressure on the shaft timbers. The inflow of water at any depth so far reached has not been con siderable, or more than could be kept under by bailing and pumping with small pumps. On the Kalgoorlie held the largest inflow is about 20,000 gallons per 24 hours, and is derived chiefly from between the 400 ft. and GOO ft. levels.

Boring out Shaft Bottoms. — The systems followed in the locations of the drill holes in the bottoms of the shafts may be classifled under the names of “stope- cuts” and “centre or Y-shaped cuts.” Opinions differ as to which is the better system, bnt a comparison of the footage sunk by them shows that one has very little advantage over the other. The use of the stope-cut is slightly more frequent than that of the centre-cut. By using the stope-cut it is a simple matter to maintain one end of the shaft deeper than the other, and thus facilitate the bailing of water and the tilling of buckets with broken rock, and when tiring out the bottom, the rock is projected against the end of the shaft and not directly upwards, as would be the case with centre cuts, and, therefore, there is not so much risk of damaging timber over head. The advocates of the centre-cut system have also many arguments in its favour, but in the end the factor chiefly governing the choice of one or the other must

SHAFr SINKINCI AND TliMEERlNG

be the nature of the country rock and the training of the party of miners who are going to operate. The boring of the shaft is universally performed by means of machine-drills, having cylinders of 3% inches. The machines are operated by com pressed air, at a pressure ranging from 80 to 90 lb. per square inch. The diameter of the steel used in drilling varies, according to the kind of rock to be bored, from IVs to 21/4 in., the latter being cruciform in section. Both cruciform and chisel- shaiied bits are used, though on some mines the crnciform bit is not in favour. The first, or “iitching” bits, bore to a diameter of 3 in., second bits to 2 in., third bits to If 2 in., and the finishing bit to fi/l in. tn the setting out of a shaft great care is taken to have the ends jjerfectly square and to maintain them so while sinking, and the excavation must be made to a size that will keep it well clear of the outside line of the timbers, and yet not so large as to necessitate much packing or filling between the rock-walls and the timbers. In order to ensure that the shaft will be sunk verti cally, heavily weighted plumb-lines, are hung in each corner of the shaft. Their position indicates the inside angles of the timbers when in place. These lines are hung after each sink of the bottom has been cleaned out, and, when necessary, the sides are trimmed and squared and cleared of all xn’ojecting lum})s and masses so that they shall be ready for the setting of the wall jilates and ends.

Stope-cut. — In the first exanq:)le given of this method, and shown in Fig. 1, the stretcher-bar and machine are fixed at a distance of two feet from one end of the shaft. From this point the total number of holes required for the first cut are drilled. As a rule, eleven are necessary. The two holes marked A are bored so as to incline at an angle towards the centre of the shaft. Rows B and C are bored to greater deDths, at an angle more nearly apxjroaching the vertical, while the holes in row D quite at the end of the shaft are vertical, or with a slight inclination outwards, so as to keep the end of the shaft well open. The depth of this row of holes would be about 6 feet. The two holes — constituting the cut — are fired and the rock cleaned out. The firing of rows B, C, and D, follows in rotation, and they are cleaned up as fired. The excavation resulting from this operation is shown in Fig. 1. In taking out the second cut, the machine is rigged at the ojposite end of the shaft, and boring proceeds as in the first cut, but with the difference that now only three rows of holes, marked E, F, G, are required, and a total number of nine, as against eleven holes in the first cut. Rows E and F are deeper than those in the first cut ; this is made possible because they are being fired to a face, and the rending of the rock is greatly facilitated by the removal of the first cut. The total number of holes re quired is twenty. The depth to which the shaft is advanced on the completion of the second cut is from five to seven feet in country that is recognised as being very hard.

A second example of this method is one in somewhat easier country and re(]uiring fewer holes to be bored. As in the preceding examxfie, the length of the shaft lies jarallel to the lode. The bar and machine are rigged a little nearer towards the centre of the shaft than in Fig. 1, and the total number of holes, nine, are bored over the entire length of the shaft. The use of an arm on the bar enables the machine to be placed in the required positions, forward or behind the bar. The holes are fired in the rotation of A, B, C (as in Fig. 1), and one row at a time, and

Vp]St Afsthalian Mining Practice.

— . —

fShctvin poiitiofi driH-holes,_

Fig'. 1.- Diagram showing “ Stope-cut ” method used in Shaft SinKing.

Shaft Sinking And Timbering

the rock is cleaned up after each round. At each of these sinks the advance in depth ranges from 4 ft. 6 in. to 5 ft. The depth to wliich the holes are bored is arranged so as to maintain a decided incline on the shaft bottom, and thus facilitate the bailing or pumping of water. The inclination of the bottom is maintained by boring from opposite ends of the shaft alternately.

The third example of this method of boring gives an instance in which the length of the shaft is placed at right angles to the line of lode. The strata of the rock underlie to the west, and advantage of this is taken in locating the holes to be bored. The direction of the holes is from west to east, or, approximately, at right angles to the bedding of the rock. As in preceding examples, the bar and machine are rigged twice, or two bars and machines can be used simultaneously and the entire bottom drilled over. An arm is used on the bar so as to adjust the position of the machine. The holes are fired in the rotation marked A, B, C, etc., on the accompanying diagram (Fig. 2). The three marked A, forming the cut, are first fired and cleaned up; the two side holes B follow, with C as an “easer”; and then D and E holes in their respective order. On occasions, it is found that the centre D hole is not required. The eleven holes thus shown complete the firing of the eastern end of the shaft. The solid bench of rock remaining on the western division of the shaft is then bored, and, owing to the better “ get away” for the explosion, caused by the removal of the first cut, only eight holes are required. The three marked F, F, H, are stoping holes inclining towards the eastern end of the shaft. The G, G, holes, and the remaining three ( J, J, J) are put down almost vertically, or inclining slightly outwards, if at all. These eight holes are fired in alphabetical order, as marked, and the cleaning up of the bottom is accomplished after the firing of each round. The total number of holes drilled is eighteen or nineteen, and the average advance of depth of shaft after the completion of each sink is about 9 feet.

Centre-cut. — The centre-cut system of sinking shows less diversity in individual instances than does the stope-cut method. The variation that exists is chiefly governed by the nature of the rock, and its form of stratification. This may sometimes require a greater or less number of holes to be drilled. In some instances it is found advisable to place the V-shaped cut towards one end of the shaft instead of keeping it in the centre. The information gathered from various mines shows that in this method the number of holes bored varies from eighteen to twenty-four. In the instances referred to, the length of the shafts lies parallel to the strike of the lodes. The plan followed in boring with the V cut in the centre of the shaft is complete with eighteen holes. Two bars and machines are rigged, their positions in the shaft being from 12 to 18 in. from either end. Tvm machines are worked simultaneously, and the whole shaft bottom is drilled over before firing. The V is formed by boring three inclined holes, on each side of the centre line, designed to meet at their lower ends. The firing of the holes is })erformed in three rounds. The first round comprises the lioles forming the V cut, and this is then cleaned out; in the second round six holes, three on each side of the cut, are fired and cleaned up; and finally the round of end holes is dealt with. The depth to which the shaft is extended at the finish of each sink varies from 5 to 6 ft.

A second example of this cut is that in a shaft of dimensions similar to the preceding one. Here, owing to the country being harder and more difficult to break.

Wes']’ Australian Mining Practice

hS

sS

.0 Ip

It

to

Q

S a

si.

t

c7/7c/ r7eanec/ out tj

-'jT-' fp Cj

y/ojoe

k. S§"

Co

':a

I'

to

Uj

a

1'

%

lisl

tol

t05?

HoJes fo 6e //reoi in a/p/iabetioal orcfef

Fig. 2. A Variation of the “ Stope-cut ” in Shaft SinKing.

Shaft Sinkinc; And Timbering

twenty holes are required for each sink, and the V-shaped cut is jhaced slightly to one side of the centre of the bottom. This gives nine holes in one end of the shaft and eleven in the opposite end, of which two, placed midway between the second and last rows and nearer the middle line of the shaft, are designed to act as “ easers.” In this instance, as in the one first quoted, the whole of the shaft bottom is bored out before firing is begun, and two machines are used at one time, working from the ends of the shaft towards the centre. With each .sink the shaft is deepened, on an average, by about 6 ft.

The third exanqde of this system of boring is one taken from a shaft of larger outside dimensions than those of the two former, and with its length parallel to the line of the lode. In this instance twenty-four holes are bored by two machines placed near the opposite ends of the shaft. The position of the holes and the rotation in which they are fired are shown in Fig. 3. An average depth of 6 ft. is obtained on the completion of each sink.

The information contained in the foregoing text and diagrams presents typical examples of the variations in methods of shaft-sinking on the Kalgoorlie field. In the shafts of four mines in which the stope-cut method is employed, three are placed with their length parallel to the line of lode. These show an advance in depth at each sink of from 5 to 6 ft., and a monthly footage of from 40 to 50 ft. The fourth mine, with its shaft placed at right angles to the line of lode, shows an advance in each sink of from 7 to 8 ft., and a monthly average footage of 60 ft. This difference may be owing in part to the location of the shaft across the main joint-planes of the country affording an easier breaking of the rock. The varying degrees of hardness and toughness of the rock must, however, be taken into account, the differences in this respect between one mine and another being often very considerable. In the mines that use the centre, or V-shaped cut, the advance in depth at each firing is shown a. being from 5 to 6 ft., while the monthly advance ranged from 40 to 60 ft. In considering the monthly average advance in depth of these shafts it must again bo borne in mind that in each instance the ore supply to the reduction works, together with the raising and lowering of men at change of shifts, and the handling of all timber and stores, has also to be carried on. Consequently sinking cannot be pushed ahead as rapidly and economically as would be possible in a case in which no work but sinking was being undertaken. An excellent illustration of this is given on page 57 under “Cost of Shaft Sinking.”

Explosives and Firing. — In the majority of mines blasting gelatine is held to be the most effective in results. In others, gelatine dynamite is found to be suffi ciently strong, while in a few instances blasting gelatine is employed to take out the first cut, and gelignite is used to break out the remaining ground. In this, as in bor ing, the practice will be governed by the character of the rock.

The quantities used in firing out a sink vary from 80 to 130 lb. Taking the average depths reached in the firing-out of nine shafts, this would amount, approximately, to 18 lb. per foot of depth gained. The diameter of the plugs, or cartridges, of explosive is IVs in. To explode the charges, fuse and detonators are universally in use, having been proved to be both safe and economical. To ensure a perfect explosion, and to minimise the volume of poisonous gases that may be

West Australian :\Iining Practice

generated from ignited bnt nnexploded cartridges, the No. 7 or even stronger, detonator is used, imperfect ex].)]osions l)eing chiefly dne to the use of weak detonators.

Firing by electricity has not met with favour, and is not in use on the Kalgoorlie field, and in instances where it has been tried it was found that holes frequently missed fire. As far as circumstances will permit, firing is arranged to take place just prior to the hour of “crib,” or meal time. This allows more time for the smoke to draw out of the shaft, and for a reduction of temperature prior to the return of the men. Apart from this, twenty minutes is the average time in which miners are aide to resume work in a shaft after firing. The ventilation of the shaft is greatly facilitated by keeping the timber as close to the l)ottom as i)ossible and by the division of the shaft into compartments. The plan commonly adopted of ventilating with compressed air hastens the expulsion of the fines, though this is an expensive method, and its use has to be kept within proiDer limits.

Shapt Sinking And Tiaibeeing

A scliechile of explosives used, showing' the advance in dei)th at each firing, is sulpioined: —

WEfT AUSTRALIAN lillNTNG PRACTICE

Removal of Broken Rock. — -The cleaning out of the shaft, after firing each round of holes, is accomplished by shovelling into l)nckets, or kilfifies. When the practice of sinking by direct hoisting from the surface is followed, the rock is eitlier hoisted by the main winding engine to the brace, or to some level in the mine where it can be utilised for stope-filling. If, however, this method is adopted no pent-house — a means of protection to the shaft-men which is dealt with later — can be constructed in the shaft. The more common practice of hoisting from the bottom of the shaft is to place a single-drum hoisting-winch in the plat at the lowest level of the mine, and then to raise the rock to that station. There the kibbles are emptied into trucks and when a rake of these has been filled they are sent up in cages or skips to such points overhead as may be determined. Side-tipping buckets - are mostly used. When this system of secondary hauling is adopted, the two main hoisting compartments of the shaft are closed just below the winch-plat by means of a pent-house; this secures the shaft-men from all danger arising from the fall of rock or other objects from the plat or from the levels above. The third, or ladder, compartment, is used for sinking purposes. It is close-timbered for a few feet above the winch-plat and is covered with a ]mir of stout wooden doors lined with sheet steel. These are made fiat in some instances, but are usually constructed to form an inverted Y when closed, the edges meeting over the centre line of the compartment. An opening permits the bucket rope to pass through freely. The hoisting of the bucket opens the doors, which close after the passage of the bucket; this obviates the danger of any rock falling upon the men when the bucket is tipped. The rock is emptied direct into trucks, or on to a raised platform, and subsequently loaded into trucks. The winch is operated by compressed air. The winding-rope passes over a small grooved pully fixed at a convenient height in the ladder-way above the ]fiat and is attached to the bucket. A wire line and knocker serve as the mode of signalling between the shaft-men and the winch-driver. After charging the holes to be fired, and before lighting the fuses, the miners give the fir ing warning — seven knocks. The driver thereupon raises the bucket one whole turn of the winding drum and lowers it back to signify that he is at his post. The fuses are then ignited, their length being such as to allow ample time for the men to reach the winch level and proceed to a place of safety. Immediately the lighting is effected, the miners step on to the liucket, give one knock as a signal to the winch-driver, and are immediately hoisted to the plat. The exploding shots are carefully counted, in order to be certain that all have gone off and no hole has missed fire. Where winches are used for raising or lowering men, pressure gauges are placed on air pipes in full view of the winch-driver and. immediately before firing, signals are exchanged with (or are sent to) the surface so that there can be no danger of the supply of compressed air being cut off.

Fig. 4 shows the arrangement of bucket, traveller, etc. As the depth of the shaft is increased and the timber is put in jfiace, a frame, termed a traveller or “monkey” is occasionally brought into use to prevent excessive oscillation of the bucket in its passage through the shaft. (See Fig. 10.1 The adoption of this device allows the bucket to be raised and lowered at greater speed than would otherwise be advisable. The traveller moves on 4 by 3 in. wooden guides fast'ued to the shaft timbers on the ends of the compartment. The rope passes freely through

Shaft Sinking And Tiaibering

Fig. 4. — Shaft Timbering Spaced Box System,

West Australian Mining Practice

tlie traveller, and the latter can be put on or removed from the rope at will. In the ]n’ocess of hoisting or lowering, the traveller rests on an iron collar attached to the rope a few feet above the bucket. On being lowered to the bottom set of timber, the traveller rests upon blocks of wood fastened to the guides, while the rope runs through till the bucket is at the bottom of the shaft. On ascending, the bucket is hoisted steadily till the collar on the rope engages with the traveller and takes it up; the speed in hoisting can then be increased.

The use of the traveller or monkey is not without its disadvantages. Even where the greatest care is taken in its design and construction it has been found impossible to ensure that the monkey will always travel freely up and down on the guides, and many instances have been known of the monkey “hanging up” and it will be realised that this is a source of increased danger to the men working in the bottom of the shaft. If the monkey hangs up when the bucket is being lowered there is always a danger of its falling away after the l)ucket has descended below it. When this occurs serious damage may ensue. Instances are on record of the monkey falling with such violence on to the stop as to break the rope, and even if this should not happen there is always a jiossibility of the monkey itself being damaged or broken, and pieces of it falling on the men below. It will also be readily understood that if the hanging up should take place when men are l)eiug lowered a disastrous accident may result. Very great care must be exercised in fixing the stops at the bottom of the guides on which the traveller runs; they should be of sufficient strength to withstand the recurring impact of the monkey in its descent. There is also the liability of the stops being knocked out and, in addition to the danger of their falling on the men below, much damage may be done to the shaft owing to the monkey fail ing to engage with the guides in its subsequent ascent.

There is a method applied to direct hoisting in shaft-sinking (though one now almost obsolete in Western Australia) which permits the use of cage and truck at the bottom of the shaft, and, therefore, does not necessitate the removal of the cage when hoisting from the bottom of the shaft, nor does it prevent the cage from being used at other times when hoisting is proceeding from other levels. The main feature of this arrangement consists of having supplementary guides, two on each side, fastened to the cage so as to permit the ]mrmanent guides in the shaft to lie between the supplementary guides as in a channel. The sup plementary guides are 35 ft. loug, their lower ends being flush with the bottom of the cage. They are firmly bolted to the frame of the cage, and at the points where the iron guide-shoes are fixed, the guides are recessed so as to permit them to lie close against the permanent guide in the shaft. The lengths projecting above the hood of the cage are held in position and braced with steel plates and bolts. The centre conpiartment of the shaft is used for hoisting, and the permanent guides are in position down to the lowest set of timber. The cage, furnished with supple mentary guides, descends to the bottom of the shaft — usually not deeper than 20 ft. below the lowest set of timber — and consequently a length of 15 ft. of the supple mentary guides remains engaged with the permanent shaft guides. This has proved to he ample to secure the safe hoisting of the cage and its load from the bottom of the shaft. As soon as the cage is engaged with the permanent guides for the full length of the supplementary guides, the hoisting speed may be increased, and the

Shaft Sinking And Timbering

WEST AUSTR.iLIAN MINING PRACTICE

load hoisted direct to the surface or to any level in the mine. No trouble has been experienced from the supplementary guides passing the timbers throughout the length of the shaft. In using this method, no second handling of the rock is re quired, as it is loaded direct into the truck in the cage and thence can be run out to any level to which it is hoisted. In one instance on the Kalgoorlie held this method was used in sinking a main shaft to a depth of 1,000 ft. Fig. 5 illustrates the application of this method and shows the position of the cage and truck immedi ately prior to timbering a further section of the shaft.

In direct hoisting, the shaft is open from surface to bottom, and there must always be a risk of small pieces of rock or other material falling from above and causing injury to the men below. In the use of secondary haulage, where only the third compartment of the shaft is used, the two main hoisting compartments can be securely closed so as to afford protection from falling bodies. This is universally done in mines where hoisting from upper levels is in progress simultaneously with shaft-sinking.

Pent-houses. — The closing of the two main hauling compartments of the shaft for the protection of workmen engaged in sinking, as referred to in the preceding- paragraph, is effected by the construction of a strong barrier across the shaft to intercept falling objects. JSuch a structure is known as a pent-house. Its main features are solidity and elasticity. It must afford adequate protection against small bodies falling down the shaft, and must also i)0ssess suflieieut strength to safely with stand the impact of, say, a falling cage. \'ariations in small details of construction occur in different mines. The pent-house is placed in the shaft a few feet under the plat of the lowest working level, and remains there until lower levels are opened out; before sinking is resumed it is removed and again fixed below the bottom plat. In addition to the main pent house it is not uncommon, as sinking proceeds, to place a second or temporary one at a lower depth as an extra safeguard. The 23rotection of the mouth of the hoisting comi)artment by means of doors has already been referred to. The following are two examples of the methods of constructing iDent-houses: —

In one instance, two 12 by 12 in. jarrah'“> bearers are i)laced across the ends of the shaft 8 to 10 ft. below the level of the winch ilat, and are let into hitches deepl} cut in the solid rock. The inside edges of the bearers are brought flush with the line of the shaft timbers. Upon the bearers are laid two pieces of 10 by 10 in. timber parallel to the length of the shaft, and over these, laid closely side by side, are 12 l)y 12 in. timbers forming the bed for the filling. From the bed-logs, angle Iieces of 12 by 12 in. timbers are jlaced from side to side of the shaft at an incline of about 15 deg., two in each compartment. The whole space, from the bed-logs iqD to within two feet of the plat, is then filled and well jmcked with broken rock. The timbering of the end of the shaft adjoining the hoisting conqartment is strengthened by a lagging of 6 by 6 in. jarrali held in position by 9 by 3 in. framing Fig. 6 illustrates this form of pent-house.

A second example exhibiting details varying from those in the jreceding one is illustrated in Fig. 7. In this the bearers are round logs 12 inches in diameter, laid closely side by side across the entire length of the two main hoisting- compartments, the ends being hitched into the walls on either side. In places

West .\iisU'.ilian hardwood.

SHAFT SINKING AND 'rKDIFRING

Pent House

Fig'. 6. Pent House with bsarers, bed log's and angle pieces of 12 by 12 in. timber.

West Austealian Mining Practice

where the country rock is of a somewhat soft or “rotten” character, extra security is obtained by placing round logs 12 inches in diameter along the sides of the shaft with their ends well hitched into the rock for the bearers to rest upon. This precaution is not, however, commonly required. Above the bearers a %-in. steel plate is laid and above this for a height of about nine or ten feet, the shaft is closely packed with bags of sawdust and shavings. So far, there is little important variation between this plan and the one previously described. The essential differences consist in providing a ventilation passage through the pent-house, in addition to that formed by the temporary hoist ing compartment, and the installation of a special emergency safety door designed to close the compartment in the event of the dividing timbers being burst outwards. The ventilation passage is at that end of the shaft opposite the hoisting way, and is formed by cutting out the rock behind the end timbers of the shaft. The lower opening is made just below the pent-house, and the outlet opens into the shaft above the winch plat. This additional outlet insures the better ventilation of the shaft after each firing. The emergency safety door is made of Mt-in. steel plate; it is stoutly hinged on the bearers forming the bed of the pent-house, and stands upright against the outside of the timbers forming the end of the centre compartment. Its upper edge is held in place by a wooden catch designed to give way on the moment of any bursting out of the centre timbers. In this event the door would be released and would fall across the hoisting compartment at a steep angle and any falling material would thus be deflected on to the fllling of the pent-house, and would not fall down the hoisting way upon the miners.

The foregoing examples are typical of the methods adopted with a view to giving complete protection to the miners engaged in shaft-sinking. It would, doubt less, be found that in every mine on the field there is some variation in construction due to the individuality of the respective mine managers. However, in each instance the special method adopted has been found to be thoroughly efficient and secure. Figs. 8 and 9 illustrate other types of pent-houses.

Shaft Timbering. — The timbering of a shaft comprises the placing in position of the wall and end plates or frames, the dividers or centres which divide the shaft into the number of compartments required, the cage-guides in the two hoisting com partments, and the ladders and resting platforms in the third compartment. This work is done in sections, commencing at the surface and descending as shaft-sinking proceeds. The depth of any section is chiefly determined by the nature of the rock or country. The presence of soft or dangerous country may require timber to be put in at short intervals, while in hard, good holding ground, very considerable depths may be attained without even a “stick” being necessary to secure it. Even when sinking in the best class of country, it is considered advantageous to have the shaft timbered as closely to the bottom as may be found convenient, because at every firing the concussion severely shakes the shaft, and at any time may cause the loosening and subsequent dislodgment of pieces of rock from the sides, possibly with the unfortunate result of an accident to one or more of the miners. In addition to this very good reason, there is ventilation to be considered, and with the timbering kept well down towards the bottom, the escape of smoke after firing and the cooling of the shaft, are greatly accelerated and, consequently, there is less delay in

Shaft Sinking And Tbibering

Pent-house with ventilation flue and safety door.

42 WEsa’ AUSTRALIAN MINING PRACTICE

Fig'. 8. Pent-house showing slight variation in detail of construction.

Shaft Sinking And Ttmbeking

the resumptiou of work. The Kalgoorlie held gives two examples of shaft- timber ing, one being the “box,” or close, and the other the “square” or frame set method.

Box System. — This is the more common of the two, and in various mines difterences in its application are found. In many instances the wail and end plates are separated by chocks, or distance pieces, leaving an open space of two or more inches between each set, while in others the plates are htted close to one another and form a tightly-joined box. A set of timbers comprises two wall and two end plates, and as many dividers as may be required for the partitioning of the shaft into the desired number of compartments — usually three. The spaced method presents several advantages over the close system, except when passing through line or gravelly country. The spaces permit a certain amount of play to the timbers when swell ing from moisture, and they make it possible to ease an undue strain on the timbers, from swelling or sliding ground, without having to remove a plate from the shaft. There is also an appreciable saving in the quantity of timber required. The spac ing of the plates is in some instances effected by nailing chocks of wood between each set at the corners of the shaft. But in this there must always be a certain amount of danger of the cliocks at some time becoming loose and falling out. The safer practice is to form the raising chock in the solid timber on the end plates and thus obviate tlie danger of the loose chock. The solid chock method is now more generally adopted and is shown in the following example of close timbering a shaft. Figs. 10, 11, 12 and 13 show the manner in which the timbers are cut, and how they are placed in position. The -shaft measures 13 ft. 9 in. by 5 ft. within the timbers. It is divided into three compartments, tlie two for hoisting being 4 by 5 ft. in the clear, and tlie third or ladder compartment, 5 ft. by 5 ft. 3 in. The wall and end plates and tlie dividers are 8 by 3 in. sawn hardwood — salmon-gum (“) or morrel (") — (Fig. 13), and the cage-guides in the hoisting compartments are 5% by 4 in. jar rah.

The wall plates are checked to a dejDth of one inch to form a shoulder against which the end plates butt. At each end of the end plates is cut a tongue or tenon 22 in- deep which separates the two wall plates and forms the solid chock or distance piece referred to, thus breaking the line of jointing by engaging portions of two wall plates. The wall jilates are grooved to the depth of an inch at the iioints at which the dividers, forming the partitions of the compartments, will intersect them. The dividers are furnished at each end with an inch tongue to ht into the groove in the wall plates, and are laid close together so as to form solid walls to the centre hoist ing compartment; they thus assist to create an upcast or downcast current of air for the better ventilation of the shaft. As in the end plates, the dividers are arranged so that their joints do not correspond with those of the wall plates. In addition to dividing the shaft into compartments, these timbers, with their length opposed to any lateral movement of the ground, constitute a large element of strength.

The cage-guides in the hoisting compartments are fastened to the timbers by means of Vg-in. coach screws, the heads of which are counter-sunk so as to avoid any danger of being canglit by the shoe of the cage when hoisting is in progress. The guides are usually 20 ft. long, their ends being dovetailed to form a good and solid joint, and the faces and sides are planed to reduce friction. On the occasion of timbering

(a) West Australian hardwoods.

Fig. 9. Another type of Pent-house.

WEST AUSTEALIAN >rTNIX(l PRACTICE

Shaft Sinking And Timbering

any section of the shaft, a point is selected at such height above the bottom as may be deemed advisable. Hitches are cut in the walls at botli ends of the sliaft to receive the bearers supporting the first set of plates. The hitches are usually drilled out completely, though in some instances they are blown out with small charges or “pops” of explosive. The depth to which they are cut into the walls is determined by the character of the rock; in hard country a few inches will be sufficient, while in poor holding ground it is necessary to make the hitches from 18 to 24 in. deep. The bearers are timber of not more than 8 by 8 in., and their inner edges are laid flush with the inner line of the ])lates. After being placed in the hitches, the bearers are well wedged and secured; upon these the wall plates are laid, and the first set of ends ])laced in position. After two or more sets have thus been temporarily placed, the dividers are set into the grooves of the wall ])lates. At the corners and also opposite the dividers l)etween the timbers and the side of the shaft two 8 by 2 in. planks are placed upright against tlie wall and end ]ilates, and are held in position with wooden wedges. Before finally fixing the timbers, great care is taken to see that they stand plumb with the up]mr portion of the shaft already timbered. Tliat having been done, the wedges are driven home and the plates brought flush with their joints. The space between the plates and the wall of the shaft is care fully packed with rock, the ])ieces used for this purpose being solid and measuring not less than 3 inches in any direction. This ]iacking is carefully laid and well rammed in place so as to form a backing as nearly solid as possible; the work then proceeds u])wards until connection is made with the timber previously put in. When secondary hoisting is in use, the fixing of the cage-guides in the two main hoisting compartments and the ladders, etc., in the third compartment, is deferred until sinking is stopped for a time and the pent-honse has been removed. Before sinking is resumed, care is taken to ]'rotect the lowest sets of timber from injury during blasting ojierations. This is usually accomplished by suspending lengths of stout round timber from the sides of the shaft and from the dividers by means of chains or wire roy)e. These hang loosely a few inches below the lowest set of timber, and serve to break the force of any upward flying pieces of rock.

In the system of close timbering a little less cutting and fitting is called for, as no space between the plates has to be provided. The wall plates are checked at each end to form a shoulder for the end plates, and are grooved vertically at those points at which dividers are to be placed to form the various compartments of the shaft. The plates are laid closely one upon the other, thus forming tight joints, but care is taken to see that the joints of the end plates do not correspond with those of the wall jdates. The method of putting the sets in position is precisely similar to that described in the first example, though the upright planks at the corners are not commonly used. Careful attention is, however, given to the wedging of the plates and the packing of the space between the timbers of the shaft walls. In comparing the methods of shaft timbering already described, that of the spaced system has many advantages over that of the close system. The latter requires at least 20 per cent, more timber, and it has the great disadvantage of not atfording the same facilities for placing a stage in the shaft for the use of men effecting repairs, as does the system of spaced timbering. Moreover, the former does not afford any means for easing the timber in swelling ground. It will be noticed that in the older shafts on the field the thick ness of the timber used, both for plates and dividers, is usually not more than two

West Australian Mining Practice

Fig 10 Arrangement of bucKet and traveller for raising broKen rocK from shaft,

in course of sinKing.

Shaft Sinking And Timbering

Fi. n. Shaft Timbering- detail of box system.

-18 Avest Austrai.Ian Mining Practice

Fig'. 12.— Shaft Timbering' - detail of box system.

Shaf Sinking And Timbering

Fig. 13.— Shaft Timbering showing detail of wall and end plates.

AVEST AUSl’RAI.IAN AITNTNG PRAOTTOE

iiielies. As the country passed tlirongdi is good standing ground tliere have been few instances of plates having lieen burst in through i)ressnre from the shaft walls, but when breakages have occurred, they have been chiefly due to a fault or weakness in the timber itself.

Tn view of the ])resent-day system of fast hoisting from deep levels, stronger dividers would have been ])referable — say not less than three inches; the dividers have to sustain the jar and strain produced by ascending and descending cages, and lighter timber may l)e found wanting in rigidity. This defect has been avoided in shafts of recent construction.

Square or Frame System. — The following descrijition of the square, or frame, set tind)ering is taken I'rom a shaft measuring 13 ft. by 4 ft. 6 in. r, 'thin timbers, and divided into three compartments, each 4 ft. by 4 ft. Bin., in the clear (Fig. 141. Except in size of shaft, no difference in the a]iplication of this style is found in the various mines in Avhich it is adopted. A set of timbei's comprises two wall plates, two end plates, ami the two dividers required for jiartitioning the shaft into three compartments. In addition to these are the ])Osts, or stnddles, eight in number, which are placed vertically lietween the wall and end plates of two sets, and are placed in the corners of the shaft and at the points where the dividers engage with the wall plates. Planks forming the lining or lagging, cleats for the ]danks to rest upon, and bearers, cage-guides, ladders, and platforms, comidete the list of timbers required. The wall and end plates are 8 by 8 in., and are checked at the ends to a depth of 4 inches each to form joints at the corners. To receive the dividers, the wall plates are mortised to a depth of one inch, ta[)ering from a width of B inches at the upper side to 3 inches at the lower. Mortises to receive the posts are cut on the np])er and under sides of the wall plates; those for the corner posts measure 4 by 4 inches, and for the intermediate ones, at the divisions B by 3 inches and are cut to a depth of one inch in each instance. Six 1-in. holes are bored through the wall plates at regular intervals to receive the %-in. bolts used for hanging the frames while being fixed in position. The lagging used is 8 by 2 in. planks, supported on cleats 2 by 2 in. fastened to the outside of the plates. The distance between frame and frame is 5 ft. 8 in. in the clear. The ladder compartment is closely partitioned off from the adjoining cage compartment by lagging set in slots, or grooves, cut in the dividers, while the two cage-ways are left with open frames. AVhen the sets are being placed in position in the shaft the work is commenced im mediately below the standing timber and is continued downwards contrary to the practice followed in the system of box timbering. The timber is usually brought down to within about 10 or 12 feet of the bottom of the shaft. The lowest set rests on bearers placed across the ends of the shaft. The bearers, which are laid and wedged in hitches cut well into the sides of the shaft, take n]i the weight of the timbers in the completed section.

Description of Stage. — Tn commencing to timber, a stage is hung in the shaft by means of four chains which are made fast to two 10 by B in. Oregon

timbers, one of which is placed across each end of the shaft, and resting on the wall plates next above the bottom set from which timbering is to be commenced. Each chain has a hook at one end, and a shackle at the other; the hooks are passed through eye holts in the 10 by B in. Oregon timbers, and the shackle end is made fast to uie

Ittaft Sinking And Timbering

stage; these chains are of snfificient length to allow the stage to hang two feet below the set ahont to he placed in ])osition. The stage is constructed of two 10 by 6 in. Oregon joists 14 ft. in length, at each end of which are bolted 9 by 3 in. Oregon cross pieces 4 ft. 6 in. long, thus forming a rectangnlar frame across which 9 by 2 in. jdanking is placed close together, hut not fastened. The shackle ends of the chains are ])assed round the 10 by 6 in. joists near their ends, and the shackles are made fast to the chains themselves. When the stage is in position, the wall plates, one at a time, are first sent down; an iron yoke or shackle, with its holt passing through one of the holes near the centre of the ]fiate, is used for attaching the winch ro]ie, and one end of the ]fiate is lashed up to the rope so that it may hang as nearly vertical as possible. On arrival at the hanging-stage the lashing is removed and the jfiate swings from its centre; it is then swung oA’er to one side of the shaft, and two of the hanging-holts are attached. These hanging-holts are made in two lengths; they are of Es-in. round iron, and each has threads cut at one end on which nuts are screwed, but the length that is attached to the set immediately above the set to be placed in position has a hook formed at one end and a safety-link provided to sli]i over the point of the hook, thus preventing any tendency to open when strained. The other length of the hanging-bolt has an eye welded on one end, and this length is attached to the wall plate suspended on the winch rope by ])assing the screwed end through the hole bored for the purpose, and screwing on the nut. When the hanging-bolt at the other end of the wall plate has been attached in a similar manner, the plate is lifted by the winch, and the eyed ends of the hang ing-bolts are dropped over the hooks of the hanging-bolts from the set above, and the centre hanging-bolt is then placed in position. The second wall ifiate is dealt with in a similar manner; the two end pieces follow, and are fitted into position on the wall plates. The posts are then put into their respective mortises and the set is brought up to its true position by tightening the hanging-bolts, the threads of which are sufficiently long to allow of the nut being screwed u]i from I Vc to 2 inches. The cleats to hold the lagging are fastened on the outside of the plates liefore they are sent down the shaft. AVhen the set has been properly adjusted and carefully plumbed, it is well wedged against the rock walls. The stage is then lowered one set, and the next set of timber is placed in position. When five or six sets have been thus dealt with, the wall plates and end pieces of the lowest set have %-in. holes bored in them, two in each end piece, and six in each wall plate, through which iron spikes are driven to the rock walls, and on these are ])laced ]mles or slabs to form a bottom for the filling. The vertical slabs forming the lagging are then put into position and the set tightly ]>acked with waste rock from al)0ve, the lagging is continued up the other sets and packed, Imt when the topmost or closing set has to be dealt with, the slabs forming the lagging are placed horizontally, and ]mcked as would be the case in a shaft timbered with the close or box system. When timber ing has been completed for the time being, and sinking is about to be resumed, the hanging stage is dismantled and sent uj) to tlie plat. When timbering has been completed from })lat set to plat set (or in a shaft where intermediate bearers are in serted to support the sets, and their weight is taken up) the hanging-l)olts may be removed and again used, but the more usual practice is to leave them permanently in the sets, thus adding materially to the strength of the whole timber structure,

Fig". 14. Square or Frame Set of Shaft Timbering'.

West Australian Mining Practice

SHAFT SINKlN(i AND TIMBERING

The cage-guides are usually cut in lengths to allow of their jointing in the centre of a divider. When this plan is not followed, and a joint falls hetween two dividers, it is made rigid by means of a Vc-iuch wrought iron plate bolted on the back of the guides with coanter-sunk bolts which are let into the timljer to a depth of half an inch or more. Ordinary butt joints are chiehy used, the guides being fastened to the dividers and end plates by means of coach-screws or bolts.

In speaking of coach-screws it is well to mention that they have certain dis advantages. Owing to the shrinkage of the hard timimr used in Western Australia coach-screws are found to grip so tightly that in any length of timber it is found almost impossible to remove them. This is a very great disadvantage where it is required to renew the skid or cage-guide. It has been found to be the better practice to bolt the guides to the dividers of the shaft through and through, and on the end of the shaft to use a spike or dummy bolt five inches long, which is driven into a hole slightly smaller than the diameter of the S])ike.

In some instances the cage-guides are held in place by wedges in addition to screws or bolts (Figs. 15 and 16). In this plan the guide is let into the frame sets — from % in. to % in. — in a dovetail slot. Gn both sides of the guide, wedges 18 in. long, and tapered from IVc inches at the top to one inch at the lower end, are inserted. They are straight-edged on the side next the guide, and l)evelled on the outside edge to engage closely with the dovetail cut in the shaft timber. This method of fastening guides is not common, but it is found to be very satisfactory; in rapid winding with heavy loads the lateral strain on the guides, due to vibration, is largely — if not wholly — taken up by the wedges in the slots referred to, and not — as is usually the case — by the coach-screws or bolts. As a result, fewer repairs are necessary in the shaft and there is less interference with the winding operations — a matter of great import ance. Since the whole of the timber is ])repared on the surface and accurately cut to templates before being sent below, the lining-u]) of the guides can be quickly carried out with this system. The third compartment of the shaft is designed for a ladder- road and for carrying ])ii)es for air and water and cables for electric power and light ing. The ladders are made of I by 2y2-in. hardwood, with %-in. round iron rungs let in to a depth of one inch. They are 12 in. wide in the clear, and the depth of tread from centre to centre of the rungs is 10 in. Ladders are made in varying lengths according to requirements; they are slanted from side to side of the shaft and are placed next the hoisting compartment. Stages are constructed every 20 or 30 feet across the compartment and manholes are cut in the stages to provide a means of access to the ladders. These manholes are usually cut directly under the ladder ris ing above the stage, and the ladder from the stage below projects some three feet through the manhole.

Fig. 17 illustrates another square or frame set of shaft timber varying in some respects from the foregoing.

Cost of Shaft Sinking. — The data obtained from nine of the principal mines in the Kalgoorlie held (vertical shafts) are given in detail in the accompanying schedule. On reference to these, it will be noted that in six box-timbered shafts the cost of the completed shaft (exclusive of the cost of cutting plats at the various levels) varies from £9 16s. Id. to £12 6s 9d. per foot; and that in three frame-

54 West Australian Mining Practice

Shaft Sinking And Timbering

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S/VEtv//v<7 A'?c-r>tco Of ST£-v/n-c Shi os TO Ce/vTEieS

/Yew YY/iy Oo tYy

Fig. 16. Shaft Timbering— detail of joints and wedges.

\Yrht Australian Mininu Practice

timbered shafts the cost ranges from £12 17s. lOd. to £16 16s. 6d.; while the average cost per foot for the nine shafts works out at £12 11s. Id. The average cost iier foot of the several items enumerated is as follows: —

AVa.ges and Salaries Timber . .

Explosives Stores . .

Power . .

7 1 9.51

1 15 1.15 0 16 1.01 0 9 5.10

2 5 11.30

Total Average Cost per foot . . . . . . £12 11 4.37

The foregoing costs are those of sinking while the work of mining, develop ment, and hoisting is proceeding on the upper levels of the mine. This, consequently, necessitates secondary hoisting from the bottom of the shaft and re-handling at the upper level, involving extra expense in winch-driver’s and lander’s wages, com- ])ressed air, oils, etc. The cost is considerably less where direct hoisting to the surface is possible, and no work other than shaft sinking is being carried on.

An example may be given of direct sinking to a vertical depth of 1,000 feet in a shaft 14 by 5 feet within timliers. Three rock-drills and 18 men were employed per 24 hours. The average monthly advance was over 100 feet including time occu- ])ied in timbering and dividing the shaft into three compartments, and fixing cage- guides and ladder-way complete. The cost per foot was £11 5s. 4d., being £1 3s. 6d. ])er foot less than in other, and smaller, shafts on the same mine in which secondary liauling was necessarv.

The variations in the dimensions, within timbers, of the before-mentioned shafts (nine in number), and the quotations of the costs per lineal foot of sinking, make it difficult to coni])are one with the other. This difficulty is overcome to a great extent l)y adopting the system of reducing the costs per lineal foot to costs per cubic foot, as shown in the table on page 57. The shafts have been arranged in order of their sizes — commencing with the smallest — and have been grouped in acordance with the two different styles of timbering.

It will be seen that the shaft of smallest area (No. 6) was the most ('ostly, and that a shaft (No. 2) of nearly double the size of No. 6 and on the same line of country, costs only a little more than one-half. It is also noticeable that while the square-frame timbered shafts (Nos. 7, 8 and 9) show high costs when computed per lineal foot of depth, they compare very favourably with the close- timel)ered shafts that are of nearly equal area, when computed by the cubic foot. .V comparison between shafts of large and small area indicates that those of large area are comparatively cheaper. This is probably due, in part, to the larger area permitting better results in l)reaking up the bottom by blasting. An example can l)e seen in relation to Nos. 2, 9, and 6, all on the same line of country, in which No. 6 is of small area and considerably more costly per cubic foot than Nos. 2 and 9, both of much larger area. The shaft marked No. 1 shows a comparatively high cost per foot. This is due, in a great measure, to extremely hard bars of country having been frequently met with in sinking.

SHAPT SINKlAAi AND TTMBlilRING

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A table will be found on page 68 showing the percentages of tlie several items making up the cost per foot of shaft-sinking in the various mines.

West Aestkalian Mining Practice

Fi?. 17. Square or Frame Set of Shaft Timbering'.

WEST AUSTRAl.IAN MINING PRACTICE

Chapter Iii

Shaft Sinking And Timbering

Underlay Or Incline Shafts

Sizes nf Shafts — Sinking — Cost of Sinking.

The terms “underlay” and “incline” are commonly interchangeable and are used to denote all shafts that deviate from the vertical. The term “incline,” however, may more correctly apply to an angle measured from the horizontal, and “underlay” to one measured from tlie vertical. In this reference the two terms are used to signify a shaft that follows down on the lode or vein, or in the rock near the lode. The choice between an underlay and a vertical shaft for quickly and economically opening up a mine is determined by the result of prospect ing operations in the early days of a mine’s history. The customary practice is to commence with a small shaft directly on the lode, and with it to follow the underlay, no matter how irregular or erratic, and to sink the shaft to such a depth as may be convenient, or until the average angle of the lode’s inclination has been ascer tained. If the lode is vertical, or nearly so, it is obvious that a vertical shaft is best adapted for its development, and should be sunk, for preference, in the foot- wall country in order more thoroughly to protect it from the effect of shrinkage and movement in the hanging-wall rock when the ore is being, and after it has been, extracted. Frequently however, the situation of a lode necessitates much dead work in the form of crosscuts at various levels, and from a shaft sunk in the foot-wall these would be longer and more costly at each succeeding level. A vertical shaft is, therefore, usually sunk on the hanging-wall side of the lode at such a distance from the cap or outcrop that it will pass through the lode at a certain depth from the surface, and thus tend to equalise the lengths of the crosscuts on either side of the shaft above and below the point at which the shaft intersects the lode. Occasionally, however, the lode after maintaining a fairly regular underlay for a considerable depth, makes a greater deviation from the vertical, which consequently necessitates the driving of unduly long crosscuts from the shaft. In such cases it is found advisable to divert the shaft gradually from the vertical to the incline and follow down on the underlay of the lode from the point at which its inclination altered. In the case of the lower levels of a mine showing a decrease in the average value of the ore, it may be considered good policy to follow the lode on its underlay and thus test its value by the way, in preference to sinking the vertical shaft and driving the necessary crosscuts — both works of very considerable expense.

West Austealian Mining Practice

Bo

The length of an underlay shaft innst be on, or parallel to, the strike of the lode. In view of this, there may be much in favour of placing the length of vertical shafts parallel to the lode instead of at right angles to it, as it then becomes possible to change from the vertical to the underlay without materially altering the hoisting arrangements, should such a change, at a later date, be deemed advantageous. With a vertical shaft sunk at right angles to the lode, it would practically be impossible to convert it to an underlay shaft; or, if sinking on the lode was decided upon, it would necessitate secondary hoisting by a winding engine placed at the lowest level of the vertical shaft. This arrangement would, of course, considerably increase the working costs.

In the Ivalgoorlie group of mines the early prospecting work proved that vertical shafts were best adapted to the conditions of the ore-deposits. The lodes are nearly vertical and are irregularly shaped on both foot and hanging walls, at times Imlgiug out far into one or both walls, and again contracting, in lenticular form, as they continue downwards. They thus constitute a class of ore-body that is unsuitable for mining by means of underlay shafts. In other localities it is found that an incline shaft is better adajhed to the ])Osition of the lode. In exceptional instances the lode may be found to maintain a regular underlay; when this is the case it permits the shaft to l)e sunk in ore, and a skip-way to be laid down suitalde for quick hoisting. -Ml too frequentl_v, however, the lode is found to vary in angle of incline within com- l)aratively short distances, in some places becoming almost horizontal, and in others as nearly vertical. Conditions such as these are opposed to the economical sinking of a shaft and subsequent working, where fast hoisting of heavy loads will be required. Yet, in mines in which no large daily tonnage is required to be hoisted, and high hoisting speed is not demanded, these variations of incline are overcome to some extent by cutting down the brows of the steeper portions; but in mines that have to deal with large quantities of ore these variable tracks ai'e not ])ermissible. The alternating inclination of an underlay lode is usually ascertained l)y the aid of small shafts originally sunk for i)ros])ecting; and it may be found that the variation of the angles is contained within certain limits ])arallel to the average angle or underlay. This being the case, the i)ractiee is to use the small shaft for pur])oses of ventilation, stope-filling, ingress and egress of men, etc., and to sink a new shaft for main hoisting- purposes. The new shaft can l)e carried down in solid country, and at a distance from the lode that will ensure the shaft continuing on the foot-wall side of the lode at all lioints. By this method a regularly inclined shaft is established and it is stronger than if sunk on the lode, as its sides are in valueless rock, which remains solid and unbroken.

In those underlay shafts where is has been possible to sink directly upon the lode, the plats and drives are opened at the sides and yield a greater or less quantity of ore as a set-off against their cost; but where the shaft is carried down on the foot-wall side of the lode, a certain amount of cross-cutting through valueless rock must be undertaken until the lode is intersected. This is similar to the cross-cutting of a vertical shaft, with this exception — that in the underlay shaft the crosscut at each level would be, )ractically, of the same length, because the shaft is lying parallel to the inclination of the lode, while in the vertical shaft the crosscuts would lengthen as greater depth was reached and the underlay of the lode carried it farther away from

Shaft Sinking And Timbering

6]

the shaft. From the crosscuts off the underlay shaft, it is a simple matter to cut ore- bins beneath the levels and the lilling of the skips is facilitated by means of a chute put down through the back of the shaft.

The adoption of a vertical or underlay shaft is entirely governed the actual conditions of the lode to be mined, and its angle of inclination. In good standing- rock the underlay shaft should be less costly to sink than the vertical, as less timber will be required. On the other hand, the cost of maintenance is greater owing to the shorter length of life of the hoisting ropes, and the wear of rollers, rails, skip-wheels, and track generally. The difference in the life of ropes in underlaj" as compared with vertical shafts is clearly shown in the table dealing with Hoisting Ropes (page 8*2).

As previously mentioned, the shafts dealt with under the head of “Vertical Shafts” are situate in Kalgoorlie; they are working under similar conditions with regard to rates of wages, freights, stores, cost of water and fuel supply; the geological features too, tliough varying slightly in the case of a close comtarison between one mine and another, are broadly s])eaking, identical. Kalgoorlie is 387 miles distant by rail from Fremantle, the seaport for the Goldfields. In describing the practice on the Sons of Gwalia and Great Fingall mines it may be mentioned that the former is 546 miles and the latter 561 miles from Fremantle, and the increased rail mileage is naturally responsible, in each case, for a greater ex])ense in mining. Wages, and in one case fuel also, are in excess of the Kalgoorlie figures, as is shown l)y the following: —

Sons of Gwalia. Great Fingall.

Wages . . 8.37 per cent, higher . . 2.73 per cent, higher.

Freights . . 28.00 ,, ,, . . 32.00 ,, ,,

Fuel . . Equal . . . . . . 22.30 ,, ,,

Sizes of Shafts. — The dimensions, inside timliers, of the underlay and of the combined vertical and underlay shafts are as follow: —

Length of shafts . . . . . . . . . . 17 ft. 2 in. and 15 ft.

Width of shafts . . . . . . . . . . 5 ft. 6 in.

Number of hoisting compartments , . Two

Length of hoisting compartments . . , . 5 ft. 4 in. and 4 ft.

Length of pump and ladder-way compartments 5 ft. 6 in. to (1 ft/"'

Sinking. — The shaft-sinking includes items in every respect similar to those given under vertical shafts, except of course that rails are an additional expense in referring to incline shafts, and the costs (pioted represent the shaft completed in every particular. The cost of cutting plats, or stations, at the various levels is not included.

In the actual operations of boring the shaft bottom and firing holes, there is very little difference from the practice fully described under the head of “Vertical Shafts.” The centre-cut method of boring the holes is practised in both shafts herein referred to. This is not so much a matter of choice in these instances as of necessity: the stope-cut method is impracticable because the hauling is invariably done in the end or pump compartment, and difficulty would exist in the removal of broken material from the other end of the shaft. The drag-cut method is almost impossible as, owing

This compartment is sub-divided to form an auxiliary hoisting compartment as well as a ladder-way

WEST AUSTRALIAN AriNTNU PRACTICE

to the length of machine and the limit im]iosed hr the width of the shaft, “cut” holes cannot he effectively bored. The machine drills used vary in size from 34 to 3% inches in diameter, and are o|)erated hy coni])ressed air at a pressure of from 80 to 90 lb. per square inch. The steel is U/o-ineh in diameter and both chisel and crnciform hits are nsed. The following- tahnlated fignres will he convenient for ])iirposes of reference: —

Three-Compartmext Underlay Shafts.

Shafts.

Sons of Gwalia.

Great Fingall.

Dimensions within Timbers ...

ft. 2 in. X 5 ft. 6 in

1 5 ft. X 5 ft. 6 in .

1

Xo and Size of Compartments within Timber ,

ft. 4 in . X 5 ft. 6 in . ft. 6 in X 5 ft. 6 in.

4 ft. X 5 ft. 6 in

6 ft. X 5 ft. 6 in

Style of Timbering

Frame Sets

Frame Sets

1 Frame

9 in. X 9 in.

S in. X 8 in.

Size of Timbers Centres ...

9 in. X 6 in.

8 in. X 6 in .

! Lagging ...

Sin. X 2 in .

8 in. X 2 in ,

Explosives Used ...

Gelignite and Blasting

Blasting Gelatine

Gelatine

Explosives used per ' Sink "

70 Lb.

80 Lb

Depth of " Sink

5 ft.

5 ft. 6 in. to 6 ft

.Average Monthlv .Advance

46 ft.

45 ft.

In the Sons of Gwalia shaft, hoisting in connection with sinking operations is performed in the end or ) com])artment, a pent-house being placed in position in the two main hoisting compartments, just below the lowest level in which development or stoping operations are in })rogress. The form of pent-honse does not offer any material difference for comment from those already described. Rails are laid in the pump compartment, and l)y means of a winch, stationed in one of the lower levels of the mine, the broken material is raised in a small skip to any desired point. A set of curved rails, acting on a hinge at the particular plat at which the rock is disposed of, allows the skip to be run into the ]ffat for emptying.

The amount of water met with in sinking this shaft is very small, and it is raised I\v means of a bailing skip to a point in the shaft above the lowest level then connected with the main pumping system. At this point the skip is antomatically discharged, and the water, flowing into a small concrete-lined reservoir, is led to the umqvsuni]-) immediately below. Plate Nil illustrates the a])pliances for hauling rock and water.

For the first 500 feet this shaft was carried down in the lode, but for the next ].,500 feet it has been kept in the foot-wall side of the lode. Ex})erieuce proved that in the former case inore supervision and care were required and greater expense was incurred in the repair and renewal of timber. While differences of opinion may exist as to the correctness of sinking in the foot-wall country, there would appear to lie many reasons in its favour. In the other case the ends of the shaft are in ore, which must be left standing — even if the ore is of ])rofitable value — for considerable lengths away from the ends of the shaft in order to maintain its stability. Assuming that

8TIAFT SINKING AND TIAfBERTNG

a time arrives when it is decided to al)audon tlie mine, these pillars of ore may then he removed and filling rnn in. In any case, it means that possii)ly a very large tonnage of good ore may have to remain untouched for many years. It is true that the sight of so much ore remaining unbroken would he tantalising to both mine managers and mine owners, and in the event of a falling-off in the reserves, or of the values in the stopes, the taking out of the shaft ]hllar would certainly a])i)eal strongly to all concerned. The filling of the stoi)es with “waste” would, doulffless, he carried out with extreme care, in the hope that no shrinkage would occur to affect the shaft: hut, however well filled, the ground could not he made as solid as in its original state, and an element of weakness would be introduced. The shrinkage of the filling and the consequent settling of the hanging-wall would cause increased pi’es- sure, and lateral as well as vertical strains uimn the tinil:)er. with the result that constant trouble and exiense would be exi)erienced in trying to maintain the shaft.

On taking the foregoing views into consideration, it is evident that the sink ing of an underlay shaft below the lode iu solid foot-wall country will, in the end. prove to be the more economical of the two methods; and though its cost cannot be in any degree defrayed by the ore won in sinking — as may l)e the case in sinking directly on the lode — there will be ample com]iensation in the saving of timber, reduced cost of maintenance, im])roved facilities for loading ore, and the ability to mine every ton of ore without endangering the shaft.

The square or frame set system of timbering is adopted in the Sons of Gwalia shaft. The legs are tenoned to fit into mortises cnt in the sills and caps, and studdles or distance ]iieces are carefully fitted between the respective wall plates. The ca]is are further supported by the centre pieces that divide the shaft into its several com partments. These dividers vary in size, according to the nature of the country, from 9 by 6 in. to 8 by fi in., in which the longer section is placed in alignment with the direction of the shaft. The wall and end ]ilates are of 9 l)y 9 in. section, and the dividers, two in nnmber, are 9 by 6 in. Four corner studdles 8 by 8 in., and four centre studdles 9 by 6 in., are used, the whole of these timbers, together with the 8 by 2 in. are of Oregon. Figure 18 illustrates clearly the method of joining the timbers and the relative jiositions of the various members forming a set.

As each set is placed in position it is rigidly bolted to the set immediately above it by means of five sets of %-inch bolts. Two of these are placed in the sill, or wall plate, resting on the foot-wall, one in each end-piece of the main set timber and the fifth in the cap-piece, or wall plate, on the hanging-wall of the shaft. As this method of bolting timber is entirely different from that practised in vertical shafts a descrip tion may not he out of place here. Di lowering timber into ]msition iu a vertical shaft it has been shown that the wall plates are lowered in such a manner that until they are suspended by the hanging-holts from the set above, their weight is sn]iported by the rope by which they have just been lowered, and consequently there is little or no heavy lifting required to place the main timbers in position. In the underlay shaft the sill, or foot-wall plate, is lowered into place and suspended from the hang ing-bolts in a manner similar to that just described, but there is no means of ]hac- ing the cap iu ])ositiou other than by lifting bodily. There is no head-room to erect tackle, and. as a flat hanging- wall is always liable to give trouble on account of the ground being bad, there is rarely sufficient room to erect staging for the ])ur-

(S4

AUSTRALIAN MININd PRACTICE

Fig. 18. Details of Underlay Shaft Timbers.

Shaft Sinking And Timbering

pose of sliding’ the cap-pieces into idace. When the sill is suspended on the foot- wall bolts, the end pieces are placed in their respective positions and secured by the hang’ing-l)o1ts, but not screwed np. The caj) is tlien lifted, one end at a time, into its position on the top of the end-pieces. It will lie readily understood that if the cap had to be lifted and held while the ends were l)eing placed in position and tlie various bolts attached, the work would be much more arduous and dangerous.

When the stnddles or distance-pieces are placed in their respective positions the bolts are tightened and the adjustment of the whole set into alignment follows. Instead of working with ])lumb-lines only, as in a vertical shaft, a spirit level and

template must also be used. Figure 19 shows a tem])late, straight-edge, and level, and their application. The sill must be placed on the foot-wall in the plane of the sills above it, with its centre in alignment with the shaft centre, and firmly wedged, so that if crushing subsequently occurs any movement of the sill is prevented. Then, with the careful alignment of the cap, all the bolts are drawn tight and the set completely and securely wedged. The fifth hanging-bolt passes through the cap near the centre, and is used merely to draw it into position before wedging, otherwise the long length of cap — 18 ft. Sin. — will have a tendency to sag. Bearers are placed as

West Australian Mining Practice

required at various points in the shaft; except that they are inclined in the same plane as the shaft set, they are in every respect similar to those used in vertical shafts. In the event of the caps and legs showing the effects of pressure, due to the ground proving increasingly heavy, they are strengthened by supplementary legs and caps, , or by angle braces from cap to sill between each pair of legs, and by this means the weight is taken np.

The rails used in the main hoisting compartments are of T section, weighing 45 lb. per yard, and are laid on 8 l)y 4 in. longitudinal runners placed on the sills, thus making a very solid roadway suitable for rapid hauling.

On the Great Fingall mine the main shaft was started at a distance of 740 feet from the line of outcrop of the lode, and sunk vertically to a depth of 1,200 feet. No cross-cutting took place from this shaft nntil a depth of 530 feet was reached, the ore in the u]qDer workings being mined from another and older shaft. In view of the possibility in the future, of having to extend longer crosscuts at each successive level it was decided to turn the shaft from a point 1,169 feet deep, and follow the dip of the ore-body. The lode dips, in this section, at an angle of 58 degrees, conse quently very little difficulty was experienced in making the desired change. Since the work in connection with the sinking of the vertical ])ortion of this shaft presents no feature of material interest in addition to tlie information given about similar work in Kalgoorlie, reference will be made only to that part of the shaft below the vertical portion.

Hoisting from the shaft bottom is performed in the end compartment by means of a winch, driven by air, and a kibble emptying into a bin on the lowest level. Instead of the usual pent-house, a portion of the shaft is temporarily left solid below the main hoisting compartments, the area of the sinking for a distance of 12 or 15 feet being restricted to that of the pump compartment; below this sinking is resumed for the full length of the shaft, and the pillar left affords an excellent protection to the miners. From the fact that the bottom levels of the mine are very well ventil ated no trouble in this respect is experienced in sinking. The timber used in the shaft is Oregon, and the method of jointing the square-sets is similar to that used in vertical shafts.

In deciding to convert the lower portion of this shaft into an underlay, the management selected a point at which the turn should not only be well clear of the levels immediately above and below it, but so placed that the desired grade could be maintained in following down on the lode. In the vertical portion of the shaft at a point where the deviation commences, a strong cap-piece of timber, similar in size to the cap of a plat-set, is laid lengthwise in the shaft and tightly wedged in deep hitches cut in the solid rock, on that side of the shaft where the vertical junc- ‘tions with the back of the underlay. This serves to support the timbering of the vertical portion of the shaft, and the ends of the posts and studdles are mortised into it. From below the cap-piece the side of the shaft is cut away on a curve having a radius of 50 feet, and is produced to the point at which the regular under lay shaft commences. From this point downwards, the sinking and timbering of the shaft are carried out in a manner similar to that already described. Below the

Shaft Sinking And Timbering

actual point of deviation, the vertical portion of the shaft continues sufficiently far to form a sink for the collection of, say, water draining down the shaft. Bearers are fixed in this portion of the shaft below the curve, wall plates are placed on the bearers, and posts and studdles are set up vertically on the wall plates and tenoned into the cap-piece above; the positions of these timbers coincide with that of the corners and studdles of the vertical shaft. The posts, however, are of 12 by 12 in. timber and 28 feet in height; the studdles are of the same thickness as those in the vertical shaft, but of greater width. The longer dimension stands at right angles to the length of the shaft as in a plat-set. These upright timbers are connected with the dividers by mortise and tenon joints, and are braced to the timbers on the opposite side of the shaft with strong bolts passed through below the dividers. The back of the underlay shaft round the curve is supported by posts and cap- pieces with stout lagging between ca})S and back. Posts and caps are of 8 by 8 in. timber, carefully jointed. The posts are fixed on the radial line of the curve, and their bottom or foot ends junction with the 12 by 12 in. timbers in the vertical shaft, the timbers being mortised about 2 in. deep to receive the posts.

The skip-track round the turn is carried on 8 by 8 in. bearers, fixed length wise in the vertical shaft and resting on the dividers, to which they are firmly bolted. They are, of course, so placed that they conform to the curve of 50 ft. radius. The rails of the incline shaft are spiked to the bearers and are curved to the 50 ft. radius until they meet the side of the vertical shaft, where they terminate. The ends are tapered, so as to lie closely against the timbers. Just before reaching the end of the rails, the skip, in ascending, assumes a vertical position, where its wheels are thrown out of use until, on descending, they re-engage with the rails and continue on them down the underlay. Ski])-guides, or runners, at both ends of the hoisting compart ments, traverse both the vertical and underlay sections of the shaft from top to bottom. The guides are made of hardwood, the sectional dimensions being 5 by 4 in. and the average length 24 ft. ; they are placed so as to engage with shoes on the skip frame. The shoes are turned slightly outwards at the top and bottom in order to allow a little play when rounding the turn in the shaft.

The steel hoisting rope is fended off the turn of the shaft by three grooved pulleys of 24 in. diameter. The first of these is at the brow of the turn, the second 10 feet lower down, and the third 12 feet below the second. After passing the third pulley the skip is well into the underlay and the rope quite clear of the back. Fig. 20 shows very clearly how the turn is taken, and the method of timbering adopted.

Cost of Sinking. — The items forming the total cost per foot for underlay shafts are given in the table on the next page.

WEST AUSTKATJAN :yrTETNrT PRACTICE

Three-Compartment Underl.w Shafts

— Cost

PER Foot

OF Sinking.

Shafts.

Sons of Gwalia.

Great Fir

sail Consolidated.

Dimensions within Timbers ...

17 ft, 2

in .

X 5 ft. 6 in.

15 ft

X 5 ft. 6 in.

Style of Timbering

Frame Sets

Frame Sets

Sizes of Timber

9 in. X 9 in . (

t 9 in. X 6 in.

8 in. X 8

in. & 8 in, x 6 in.

£

s.

d.

£

s. d.

Wages and Salaries

Timber

Explosives

Stores (a)

10'92

Power {b)

6'60

Repairs and Maintenance (c) ...

7'00

Total Cost per foot Sinking ...

0'29

Cost per square foot Area of Shaft

4'23

(a) Includes candles, oils, rails, fastenings, and sundries.

(b) Includes hoisting, pumping, and air for rock drills.

(c) Includes repairs and maintenance, machine drills, and steel.

The following table shows the percentages of the principal items making up the cost per foot of shaft-sinking in the various mines: —

No. of Mine.

Name of Mine.

Locality.

Wages and Salaries. Per cent.

Timber. Per cent.

Explosives- Per cent.

Stores.

Per cent.

Power.

Percent.

Great Boulder Proprietary

Kalgoorlie

Great Boulder Perseverance ...

Oroya Brownhill ...

Associated

Kalgurli

South Kalgurli

Ivanhoe

Golden Horse-Shoe

Lake View Consols

.

Sons of Gwalia

Leonora

Great Fingall

Cue

Note. — Shafts of mines numbered 1 to 9 are vertical ; 10 and 11 are underlay.

Shaft Sinking And Timbering

Fig'. 20. — Diagram showing turn in Shaft from Vertical to Underlay.

West Austealian Mining Practice

Chapter Iv

HEAD FRAMES, WINDING ENGINES, ROPES, AIR COMPRESSORS, ROCK DRILLING MACHINES AND STEEL

steel Frames — Wooden Frames— Sizes and Types of Winding Engines — Description of Hoisting Eopes Air

Compressors — Eock Drills — Tool Sharpening — Eepairs to Machines.

HEAD-FRAMES.— The subject of Head-frames, so far as Western Australia is concerned, embraces a number of different designs, and it would be impossible in these pages to do more than attempt to classify the various types in use under two headings, giving lirief descriptions of a few, illustrated by photographs and drawings. The two headings are: — (1.) Head-frames constructed entirely of steel. (2.) Head-frames constructed of wood.

Steel Head-frames. — The majority of steel head-frames in this State are used in connection with vertical shafts. Fig. 21, is a photograph of a large steel lattice- work head-frame now at the Day Dawn shaft on the Great Fingall mine. The u})per portion of this structure was at one time erected over the West Fingall shaft, i)ut was dismantled and built up to suit the requirements at the Day Dawn shaft. Plates IT, III, and show the general arrangement and details of this structure. The total height is now 100 feet. The diameter of the poppet-head wheels is ten feet, and the ropes used are of best plough steel, SVL* in. circumference, six strands, 15 wires.

The three compartments are used for hoisting purposes; the south and middle compartments for hauling ore with self-dumping skips, and the north com- l).irtment for hoisting men, tools, etc. The capacity of each skip is 36 cwt., and the total weight of skip with ore and rope is 98 cwt. The ski])s are of special design (Figs. 88, 89 and 90) being constructed so as to run from a vertical to an incline shaft. The reason for this is that the Day Dawn shaft is vertical to 1,169 feet and then underlies at an angle of 55 degrees. The total tonnage per month hoisted to the breaker-station on the head-frame is 22,000 tons of 2,000 lb. The rock-breaker station is a wooden structure, independent of the steel head-frame, thus obviating any transmission of vibration.

Plate V is a drawing of the head-frame erected over the Edwards’ Shaft of the Great Boulder mine. The structure is made entirely of steel, with the exception of the sky-shaft, which is made of Oregon, and the cage guides, which are of karri or jarrah. The legs are seamless steel tubes %-in. thick, the bottom lengths are

(a) West Australian hardwood.

West Australian Mining Practice

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Plate 11

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West Au.Stralian Mining Practice

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West Australian Mining Practice

Plate V

GREAT BOULDER PRQPRIT/=R Y. G. M. Qg. l-X. -

— STE£_L HCiqpCEflR FOR EDWAPPS SHflFT

Fi.ATlll V

Head Frames

14 in. externa] diameter, the intermediate lengths 12 in. and the top lengths 10 in. The various lengths are joined together by means of pressed-steel flanges, riveted to the tubes with a steel disc, one inch in thickness, inserted between each pair of flanges. The horizontal members of the main framing are formed with 12 by 3 in. channels, arranged back to back with a 2-in. space between.

Fig'. 21. Steel Lattice WorK Head Frame— Great Fing'all.

The brace joists are I section stiffened with Ihl-in. truss-rods. The diagonal braces are 2 by 1 in. secured to the leg brackets with eyes and {)ins, and tightened with threads and nuts in a centre ring.

West Australian Mining Practice

Tlie rope sheaves are 8 feet in diameter, supported on rolled joists 18 by

7 in.

Wooden Head-frames. — This division is again snb-divided into two classes, viz.: — (1.) Head-frames for vertical shafts. (2.) Head-frames for incline shafts.

Fig'.'; 2 2. — Pyramidical Head Frame constructed of local hardwood.

With few exceptions most of the head-frames on mines near the railway are made from timber grown in the State, principally of jarrah and karri hardwoods. Owing to the high rates for transport, practically all the mines situate at a distance from the railway use oregon in ])reference to anything else, as tlie extra first-cost of the Oregon is more than compensated for by the additional freight on the heavier timber; jarrah is nearly double the weight of oregon.

West Australian Mining Practice

Plate Ix

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The Lancefield Cold MinincCo. Ltd.

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tlie Oregon is more than compensated for by tlie additional freigdit on the heavier timber; jarrah is nearly double the weight of Oregon.

Wkst Australlvn Minin(J Practice

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timber; jarrali is nearly double the weight of Oregon.

Head Frames

There are two types of head-frames for vertical shafts — the pyramidical and the gallows. Fig. 23 is a typical illustration of a pyramidical liead-frame. The four legs are jarrah logs tapering from 30 to 12 inches in diameter, and are set at an angle of 80 degrees. Each leg is bolted down to a solid block of concrete. The horizontal beams carrying the landing-braces are 14 by 10 in. and 14 by 9 in.; the dimensions of the braces being 12 by 10 in., 12 by 8 in., and 12 by 6 in. The cap-pieces are 14 by 12 in. and the cross-bearers for carrying the pulley wheels are 18 by 14 in. The sky shaft is carried to within eight feet of the crown; this is made of 9 by 6 in. jarrah for corner posts, and 6 by 6 in. for cage-guides. The pulleys are ten feet in diameter.

Plate VI is a drawing of the head-frame on the Associated Northern Blocks.Tt would be well to note here that wooden head-frames of the pyramidical type require long and stout pieces of timber, as in the case of the joists for the landing- braces. On the other hand, for the gallows type of head-frame it is only necessary to use comparatively short and small timber, which, however, must be sawn and well fitted together. For this reason therefore, where large timber is scarce, and trans port expensive, as in isolated districts, the gallows structure is preferred. Plate VII illustrates an example of this type. The vertical height is 80 feet from sills to pulley centres, and the whole of the timber is Oregon. The main uprights consist of two 12 by 12 in. posts spaced 32 feet apart at the base an.d 10 ft. 6 in. at the cap-pieces. On the winding-engine side, two 12 by 12 in. raking struts are set at an angle of 60 degrees. The area taken up by this head-frame is 47 by 32 feet. The posts and struts rest on 12 by 9 in. sills which are bolted down to solid concrete foundations. The framing between the legs and struts is arranged to form a series of equilateral triangles, the sides of which measure 18 ft. 6 in. There are five 9 by 6 in. horizontal braces between the posts and struts and the diagonals are 6 by 6 in. All the joints are stiffened with gusset plates and bolts. The cap-pieces are 16 by 12 in. with centre pieces 16 by 9 in. Resting on the cap-pieces are two 18 by 12 in. beams, which in their turn carry the 12 by 12 in. timbers for the pulley wheels. The wheels are 8 ft. in diameter.

Taking now the final classification, which is wooden-head frames for incline shafts — Plates VIII, IX, and X give an example of this particular type. This head-frame is 70 feet high; the pulley wheels are 6 feet in diameter; the ropes are of best plough steel, 3ys inches in circumference, 6 strands, 15 wires. Self dumping skips are used, each skip holds 40 cwt. of ore, and the total weight of skip witli ore and rope is 72.5 cwt. One notable feature in this head-frame is the use of a structure for spanning the distance between the collar-set and the head-frame proper. The form of structure adopted is that of an inverted ‘ ‘ Fink ’ ’ truss. This arrange ment, in addition to reducing the amount of timber that would otherwise be necessary, permits the building of a rock-breaker station underneath the truss. The station is thus entirely independent of the head-gear, and no vibration is transmitted. The whole of the woodwork is Oregon, and the quantity used was 16,500 superficial feet. The total weight of the iron-work, including all bolts, junction plates, tie rods, etc., amounted to two tons. Six hundred cubic feet of cement concrete was used for the foundations.

West Australian Mining Practice

i .LA.TJbj

Fig. 23.— Pyramidical Head Frame showing method of increasing height.

Head Frames

Plate XI also illustrates another wooden head-frame erected in con nection with an incline shaft. This structure is 50 feet high and is built of Oregon. The pulley wheels are 6 feet in diameter, and the ropes of best plough steel are 3% inches in circumference, 6 strands, 15 wires. Self-dumping skips are used, and it will be seen by referring to the illustrations that the frame work has been specially strengthened at the tipping point. Each skip bolds 32 cwt. of ore, and the total weight of skip, ore and rope is 86.4 cwt. This particular head-frame has been in constant use since 1898, and at the present time 13,000 tons of ore per month are being hoisted over it.

The particulars of the heights and dimensions of head-frames are given in the following table: —

Head-frames.

No.

Name of Mine.

Locality.

Style of Frame.

Height.

Spread.

Materials.

Remarks.

Feet.

Base

Ft.

Crown

Ft.

Great Boulder Pro prietary

Kalgoorlie

(a) Gallows Frame

48 by 32

Oregon

8 ft. sheave

(b) Pyramidical ...

Karri- Jarrah

8 ft. sheave

(c)

Tubular Steel

8 ft. sheave

Great Boulder Per severance

Jarrah

8 ft. sheave

Oroya B r o vv n h i 1 1

Karri- Jarrah

7 ft. 9 in. sheave

Associated

Oregon

9 ft. sheave

Kalgurli

85

Jarrah

8 ft. sheave

South Kalgurli

J arrah

7 ft. sheave

Ivanhoe

no

Karri

8 ft. sheave

Golden Horse-Shoe

Karri- Jarrah

10 ft. sheave

Lake View Consols

Gallows

43 by 22

8 by 22

Oregon

8ft. sheave. Inner up rights 18 in. by 18 in. ; outer uprights 15 in. by 15 in. ; cross pieces and braces 12 in. by 12 in. ; raking struts 18 in. by 18in.

Sons of Gwalia

Leonora

Pyramidical

Oregon

6 ft. sheave

Great Fingall

Cue

Gallows

no

Steel lattice- work girders

10 ft. sheave

West Australian Mining Practice

Winding Engines.

With the increase in depth of shafts and levels, and larger tonnage treated per month, the power of the winding-engines has necessarily kept equal pace, and the engines of recent erection are designed to hoist from depths of 3,000 to 4,000 feet.

Tlie majority of the engines in use are of the direct-acting, duplex cylinder type, with cylinders ranging from 9 in. diameter with 12 in. stroke to 28 in. diameter and 72 in. stroke, and fitted with Corliss valve-gear, friction clutches, post-brakes, and reversing gear, all steam actuated. The diameter of the drums varies from 5 to 10 ft. Both drums are loose, and fitted with either toothed or fric tion clutches, and the adjustment of the skips or cages for hauling from different levels is quickly effected. The depth indicators in use are of the dial and cylindrical tyi)es, the former being confined to the shallower mines. These in many instances are supplemented by an alarm bell to warn the driver when the ascending cage or skip has arrived within a certain distance from the surface or the landing brace.

The Regulation requiring that the driver of the engine shall have a clear view of the collar and brace of the shaft has been amended, and is now optional. It was obvious that when a driver had no difficulty, by means of the depth indicators, in bringing the cage to rest at any level below the surface, it could not be absolutely necessary that he should have a view of the collar of the shaft, or of the landing braces.

On the next page is a photograph of the winding-engine operating at the Edwards’ Shaft of the Great Boulder mine. The engine is a vertical twin-tandem compound, and is connected to a surface condenser; the cylinders are 16 and 28 by 42 inches. The drums are 10 feet in diameter. With a boiler pressure of 150 lb. per square inch and a vacuum of 24 inches, the engine will lift, from its worst position, a gross load of 16,000 lb. High-pressure steam is used in the low-pressure cylinders for starting the engine and accelerating the speed under full load. When a given speed is reached, the engine is automatically compounded.

Winding Engines

Fig. 24. — Vertical Winding Engine at the Great Boulder Mine

West Australian Mining Practice

The following table affords particulars of the engines in use: —

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Avindixg Engines

Fig'. 2 5. -Steam Cross-Compound Winding' Eng'ine with patent friction clutches, etc.

Fig'. 2 6.— Another type of Winding' Engine capable of hoisting from 4,000 feet.

West Australian Mining Practice

Ropes.

Only round wire ropes are used for hoisting; these range from 2% to 41/4 inches in circumference, the size generally used being 31/2 inches. They are of six strands and have from 7 to 19 wires in each strand, the majority having 15; the breaking strain ranges from 262 to 84 tons. Great care is taken both in the selection of a rope and in coiling it on the drums of the winding- engines; also in the cleaning, oiling, and testing, at frecpient intervals, while in use. The life of a rope — that is the period during which its strength has not declined below a safe limit — must necessarily vary with the amount of travel and weight of load it is called upon to sustain, and the quality of the material used in its composition. It is only by examination and testing that this period can be determined.

d'he intervals at which cleaning and oiling take place vary from once a week to once in four weeks, according to the amount of work done by the rope and the degree of moisture in the shaft in which it is used. The outside of the rope and the shackle, coupling, and detaching hook, are carefully examined every day, while at intervals of from two to six months a closer inspection is made. On these occasions the couplings etc., are removed and a length of rope equal to not less than half the circumference of the head-frame sbeave is cut off. The shackle and coupling are annealed and examined while hot before being replaced. In some instances it is also customary to open two feet in every fifty feet of rope by means of a needle, so that the condition of the interior may be ascertained. The cleaning of a rope preparatory to oiling is accomplished by passing it between a series of wire brushes. These are adjusted so that the brush removes the dirt from between the wires and strands of the rope. For oiling the ropes various compositions are used. The lubricant is applied either by mechanical means or by hand. In the former case different devices are used, the general principle of which is to pass the cleaned rope through a bath of oil at a slow rate of speed, so as to secure an even application over the total working length of the rope. If the oil is applied by hand the medium used is cotton waste, and considerable care has to be exercised to apply the oil evenly and sufficiently; this method, however, has the advantage of permitting a close examina tion of the rope in the i)rocess of oiling.

The Mines Regulation Act requires that prior to a rope being used, a certifi cate of its breaking strain must be obtained from the makers; or failing this, the rope must be tested on the mine under conditions prescribed by the Inspector of Mines. The following is the section of the Act bearing on the matter: — Section 32, Sub-section 42: —

(o.) Prior to any rope being used for hauling in a shaft, a certificate shall be obtained from the manufacturer, or by means of a prescribed test of the breaking strain thereof, and tests shall be made at the mine to prove that the rope 'will carry at least twice the weight which it is anticipated it will ordinarily have to carry, including the weight of the cage or skip, of the loaded truck, and of the rope from the bottom of the shaft to the pit-head pulley.

(t>.) The working-load shall not exceed one-eighth of the certified breaking strain of the rope when new, and whenever after testing, as provided by regulations, it is found that the breaking strain of any rope is not six times at least greater than the working load, such rope shall be condemned by the Inspector.

In the case of a rope used for lowering and raising men, an Inspector of Mines may have it re-tested at such intervals of time as he may consider expedient. The rope must be re-shod at least once every six months, or more often if thought necessary by the Inspector, and a portion of the rope may be cut off for testing the torsional and tensile strength of the wires.

West Australian Mining Practice

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West Austealian Mining Practice

Air Compressors.

The introduction of air-compressors and machine-drills dates back to the comparatively early days of the goldfields, and the capacity of the compressors has been enlarged from time to time consequent upon increased mine development. Most of the compressors in use are direct steam-driven, compound, two-stage type. Their capacity to supply air at pressures ranging from 70 to 90 lb. ]ier square inch varies from 6 to 60 machine drills, ranging from to 3% inches in diameter. The more common capacity is 20 to 30 machines operated at a pressure of 80 to 85 lb. per square inch.

The cost of supplying compressed air to underground workings only, is a difficult matter to compute, for the reason that steam power is derived from batteries of boilers, which also supply the winding-engines and, in some instances, the power plants. The reduction plants in many cases also draw their requirements of air from the conqjressors that supply the mine. In one instance, however, it has been calcu lated that the cost of compressing 1,000 cubic feet of free air to a pressure of 80 lb. per square inch is l.ld., and in another instance it is quoted as 1.4d.

Eroni the compressor engine the air passes into receivers through mains of from 6 to 8 inches in diameter. The receivers are usually on the surface, but in some instances auxiliary receivers are ]haced at certain levels underground. They are usu ally egg-ended steel cylinders, varying in size according to the requirements of the mine, and are fitted with pressure gauges, safety valves and blow-off cocks. The last- mentioned are opened at certain intervals so that any moisture condensed from the air may be ejected and the air sent underground in as dry a condition as possible. A pipe is carried from the receiver back to the engine for the purpose of cutting off steam as soon as the desired pressure is reached. Compression is not resumed until the pressure in the receiver falls, when steam is again admitted to the engine. By this means a possible waste is prevented.

From the receivers the compressed air is conveyed underground through pipes of various sizes. The main pipe is carried down in the third or ladder compartment of tlie shaft and is from 4 to 8 inches in diameter. This is taken to the lowest level at which any considerable amount of work is in hand, but to levels in course of development only and for shaft-sinking, a smaller diameter of pipe is generally used.

In drives and crosscuts, when no timber is in position, the pipes are usually suspended by means of staples driven into holes in the walls, though in dry workings the pipes are frequently laid on the ground, clear of the rails. Stop-valves are placed at suitable intervals for controlling the air supply when repairs or extensions to the service become necessary.

Fig', 2 7. Air Compressor of 3,000 cubic feet capacity per min.

A¥EST AUSTRALIAN MININCx PRACTICE

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West Australian Mining Practice

VVRs'r AUSTR.VLIAN MIXING PRACTICE

Rock-Drilling Machines And Steel.

Macliine drills came early into use in West Australian mines; hand-drilling- was little ])ractised, exce]it during the prospecting stage of a mine’s history, and prior to tlie com])letion of the steam and air-compressing plants. The table on page 89 furnishes particulars of the machines chiefly in use. When once a machine has been ajjproved, it is diflimdt to disi)lace it. ( )ne reason for this is that no two makes of machines have intercbangeahle ]iarts and littiugs, and with more than one type in use a good deal of confusion is likely to ai'ise; the hose connections, s])anners,

Fig'. 29. Tool-sharpening' Machine Sons of Gwalia.

clamps, etc., of one make will not fit another, and trouble ensues. A further objection is the extra expense of carrying stocks of spare parts for the various types of machines.

For shaft-sinking and development work the 3%-in. machine is universally in favour. For sloping, the smaller sizes, 314 and SYo in., are used, and, where the conditions and the nature of the rock are favonratfle, the 2-in. machine does excellent work. The upkeep of a machine in constant work, including renewals of working parts and general repairs, is estimated to average about £6 per month during a life of about 18 months. The large machines are operated by two men, both of whom

West Australian Mining Practice

are held equally responsible for breakage or damage arising from careless or rough handling. A 2h2-in- machine is run by one man only, though when rigging- up or pulling down, a second man is called in to assist. The 2-in. machines are light, and can easily he carried about and set up in any position by one man.

Drill Sharpening, Repairs To Machines, Etc.

It is the practice with all mines in this State to have the sharpening of tools performed on the surface. Consideration has been given, in the case of some of the larger mines, to the possibility of sharpening drills, etc., underground, the object l)eing to avoid the ex})ense and loss of time involved in hauling large quantities of steel to the surface and returning same to the working faces. The necessity that exists for a perfect system of ventilation, combined with the disadvantage of having to provide a sharpening outfit on almost every level in the mine has, up to the present, prevented the adoption of such a practice.

In one or two mines small repairing outfits are provided on those levels in which a large number of machine-drills are at work, and only those machines are sent to the surface which require more important attention than that usually afforded by the repairing staff underground. Drill-sharpening is usually ijerformed by hand labour, but some of the larger mines have in operation mechanical sharpening machines. The latter render the work of sharpening the daily requirements of drill steel much less laborious than was formerly the case, and it is found that the “bit” turned out by these machines is quite as serviceable and as effective as those sharpened by hand.

In conjunction with the mechanical drill-sharpener special coke furnaces for heating drill steel are also in use. Figures 30 and 31 show the construction of one of these furnaces.

The tal)le on the next i)age furnishes detailed information regarding rock drilling machines and steel.

ROCK-DRlLLlNG MACHINES AND STEEL

Rock-Drills.

No.

Name of Mine.

Locality.

Maker and Type of Machine used.

Shaft Sinking and Development.

Ore Breaking.

Dia. of Cylinder. Inches.

Steel.

Inches.

Bit used.

Dia, of Cylinder. Inches.

Steel.

Inches,

Bit used.

Great Boulder Proprietary

Kalgoorlie

New Ingersoll F9 '

Q 5

Cruciform

Ifto 14

Cruciform

and Chisel

and Chisel

Sergeant H33

a

1§ to 14

C hisel

Holman

If to li

Cruciform

and Chisel

Great Boulder Perseverance

New Ingersoll F9

Cruciform

Sergeant E33

Cruciform

Oroya Brownhill

Sergeant E33 ...

H

U

Chisel

New Ingersoll B9 (B24 )

Chisel

Associated

New Ingersoll F9

Cruciform

and Chisel

Holman ...

3f

H

Cruciform

and Chisel

Holman ...

H

Cruciform

and Chisel

Holman ...

Chisel

Kalgurli

Sergeant E33 ...

Chisel

Sergeant E33 ...

Chisel

South Kalgurli ...

New Ingersoll B 24

14 and 1

Chisel

Sullivan U.B. ...

D & 1

Chisel

Ivanhoe

New Ingersoll F 9

Chisel

If

Cruciform

Sergeant E33 ...

Chisel

If

Cruciform

Golden Horse-Shoe

New Ingersoll F9

2J

Chisel and

Cruciform

New Ingersoll F9

Chisel

Lake View Consols

New Ingersoll F9

Cruciform

New Ingersoll F9

Chisel and

Cruciform

New Ingersoll B9

Cruciform

and Chisel

Holman ...

Cruciform

Sons of Gwalia

Leonora

Sergeant E33 ...

3J

Ijand If

Cruciform

Ingersoll Sergeant B24

Ijand 14

Cruciform

and Chisel

Great Fingall ...

Cue

New Ingersoll F9

Cruciform

and Chisel

Sergeant E24 .

34 to 2 k

14 to 1

Cruciform

Ingersoll Sergeant B24

Chisel

Climax ...

Cruciform

and Chisel

Climax ...

Cruciform

Climax ...

Chisel

West Austealian Mining Practice

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Fig. 30. — CoKe Furnace for heating steel for machine drills. Front elevation.

Rock-Drilling Machines And Steel

Fig. 31. CoKe Furnace for heating steel for machine drills. End elevation.

WESa ALSTRALIAN MINING PRACTICE

The following figures are quoted as representing the diameter of bits used on the Golden Horse-Shoe mine, with the lengths of drill-steel, and the approximate lU'oportions of the different sizes: —

Cruciform Bits — 3I4-in. diameter by 3 ft. 9 in. long 23/4-in. ,, ,, 5 ft. 0 in. ,,

2I4-in- - 1, fi ft- 3 in. ,,

Chisel Bits — lA-in. ,, ,, 7 ft. to 10 ft.

The weight of steel used for upkeep of drills on the same mine, during a period

of seven months, was as follows: —

Diameter of Steel.

Inches.

Octagoi

Cwt. Qr.

Lb.

Cruciform.

Cwt. Qr. Lb.

—

u

—

If

—

—

Totals ...

The following particulars of work done in stopes by rock-drills, during a

period of seven months, will be found of interest: —

Average number of machines in use . . . . . . 19.2

Nhnnber of shifts worked . . . . 541

Number of holes bored . . . . . . . . 31,660

Number of feet bored . . . . 217,280

Number of feet bored per drill per shift (8 hours) . . 20.94

Average depth of holes in feet . . . . . . . . 6.86

Tons of ore broken (2,240 lb.) . . . . . . 133,315

Average tonnage per drill per shift . . 12.85

Steel sharpened — Hand-drills . . 79,151

Machine-drills . . 130,094

Picks pointed . . 694

West Australian Mining Practice

Chapter V

Shaft Plats

Vertical Shafts — Underlay Shafts — Dimensions of Plats.

PLATS or stations are cliamliers cut in the side of the shaft, at points from which it is intended to open out crosscuts and drives for the development of a level. They form roomy places from which the subsequent work of mining com mences; wdiere the miners enter and leave the cage; where the full and empty trucks are collected; and where timber, pipes, tools and other things may be temporarily stored until required. At those levels where ore bins are constructed beneath the plat, they are known as loading stations. In vertical shafts they are invariably cut on the side nearest the lode. In mines where lodes exist on both sides of the shaft, either two plats, or a variation of the single plat, is usual; this is subsequently dealt with. It is usual to cut the plats as the shaft-sinking proceeds, but the cost of this work is not included in that of shaft-sinking referred to in a previous chapter.

Plats vary in size, according to the nature and volume of work to be per formed. It is advisable to cut a good roomy plat at the outset, as the subsequent enlargement of a small plat is not only troublesome but relatively more expensive than if it had been originally cut to adequate dimensions.

The opening of a plat necessitates the use of strong sets of timber to support the overhanging back. In framed-timber shafts, in place of wall plates of the ordinary size, 12 by 12 in. or heavier plates are used. The cap-pieces are laid under the brow of the plat, and tightly wedged in hitches cut into the rock at the ends of the shaft, the inner sides being brought flush with the shaft timbers; in these the posts and studdles of the overhead shaft timbers are mortised. The sill-pieces usually correspond in size with the cap-pieces. In what is usually described as the opening-ont set in the plat, there are six pieces of timber, the cap and sill and four up rights. Of the latter, those at the ends of the shaft are called posts, and the two inner ones are termed studdles.

The posts and studdles are pro]mrtionately strong; but as the latter cannot be permitted to reduce the width of the openings to the com])artments, their size is arranged so that in thickness they correspond to that of the ordinary shaft-centres, though they are given greater width; the width is ])laced at right angles to the length of the shaft, and has a bearing over the full width of the sill and cap-pieces. The posts and studdles are mortised into the sills and caps, and the jointing is most care fully designed and carried out. The posts and studdles are cut to a length corres ponding with the height to which it is desired to have the plat opened. The posts are connected and braced across the ends of the shaft with stout dividers, and the

West Australian Mining Practice

same method is adopted in connecting the studdles on the opposite sides of the shaft; in addition to these, strong iron bolts are run through beneath the dividers and screwed up to prevent any outward movement. The lining of the compartments is done in the same manner, and with timber of similar size to that of the other portions of the shaft. The studdles represent the weakest point in the opening set, as it is not possible to brace them laterally; but as long as the cap-pieces are of sufficient strength to take the weight of the rock to he supported, and are

Fig". 32.— Plat or Station. Vertical Shaft.

well and deeply hitched into the rock at the ends of the shaft, no undue pressure upon the studdles need be feared.

The cutting of a plat falls to the lot of the men who sink the shaft, and payment is made either in lump sum agreed upon beforehand and included in the contract for sinking, or by day labour, or by cubic foot or fathom. The boring of the first series of holes is usually done while the machine is rigged for shaft-sink-

Shaft Plats

ing, and if the ground is strong the holes may also be fired ont. This method, however, exposes a large area of country, and is possible only under circumstances in which the rock is of a good standing character. With weak ground it is safer to leave the plat-cutting until after the shaft has been sunk a few feet below the level at which the plat is to be opened. The brow of the plat can then he secured and the cutting-out accomplished with but little danger to the shaft.

Fig'. 33. Plat or Station. Underlay Shaft.

The height of the ))lat at the shaft varies from 10 to 20 ft. ; 12 to 14 ft. is commonly adopted, but 16 ft. is found to be ample for all juirposes. Plats of greater height are sometimes cut, so as to ])ermit of the erection of blocks and tackle, running on an overhead crawl for the liurpose of unloading heavy timbers, machinery, etc., with greater ease. This plan, however, is not common. Where small plats are adopted the back is generally cut to a uniform height, but in the larger ones the back is graded from the shaft down to 7 or 10 ft., a practice that reduces

West Australian Mining Practice

the cost of excavating and timbering. The backs are secured with stout cap-pieces, supported by posts at the sides of the plat, and occasionally by the ends being let into hitches in the walls, according to the strength of the hack. The lagging be tween the cap-pieces and the rock consists of 9 by 2 in. planks for strong ground, and poles or split slabs for that of a weaker nature. In wet shafts or where only slight seepage exists, the back is lined with flat galvanised iron, to keep the plat dry; the water is diverted to and drained away at the sides.

The plats are always slightly wider than the length of the shaft — in some cases very much wider, so as to provide ample room for trucks, etc. In length out ward from the shaft, they vary from 12 to 32 ft., according to the amount of work that may have to be carried out at the particular level in question. The floor is covered with h4-in. to %-in. steel plates, and may be level, although in some instances a very slight fall is set outward from the shaft in order to guard against trucks running into the shaft when left standing on the plat; the incline, however, must be very slight, so as to avoid increased labour in caging trucks.

The ladder-compartment of the shaft is closely boarded over, and entrance to the ladders is gained by means of a hinged trap-door. The hoisting compartments are closed with stout wood, or iron bars, or by gates. Bars are pivoted on the two uprights of the plat-set, and their loose ends fall into iron staples on the centre studdle. Gates, if provided, are hinged to the outer uprights, and they shut against the centre one; they are frequently hung a little out of plumb, so as to have a tendency to close antomatically.

On mines where only one lode is known, or where two or more lodes lie on the same side of the shaft, there is but one plat at each level; hut in the case where an ore-body has to be worked (or where it is desirable to conduct development work) on each side of the shaft, two plats are cut, one opposite the other. If the shaft has been sunk with its length at right angles to the strike of the lode, one plat only is required, and from it crosscuts are driven in opposite directions. Fig. 34 indicates the practice followed in dealing with various conditions.

In an incline shaft sunk on the lode itself, the plats are simply an enlargement of the entrances to the levels opening off on either side. The back, or roof, of the shaft is cut high to give sufficient headroom, and the length of the plat is carried forward horizontally, but in line with the shaft, and to a corresponding or greater width. The plat is floored with steel plates, as in vertical shafts.

In some instances the truck-loads of ore are tipped directly into skips, but the more modern method provides for ore-bins below the plat. When the bins are fall they can be drawn upon as required, the skips descending to a loading-station fitted with chutes for filling.

When an underlay shaft has been sunk in the foot-wall some distance from the lode, it becomes necessary to drive crosscuts at each level to intersect the vein. Immediately over the back of the shaft the crosscut is enlarged to form a plat, and from that point the crosscut continues outward.

To facilitate the lowering of timber pipes, rails, tools, etc., required for use on any level, a movable landing-stage is brought into use. This is stoutly built of

Shaft Plats

Fig'. 34. Double and Single Plats serving Parallel Lodes.

West Australian Mining Practice

timber and sheeted with steel plate. It is hinged to the edge of the plat over the shaft, and is raised or lowered by pulleys as required. When in use it is lowered until its outer end engages with the rails of the skip-road, thus closing the shaft on the plat for unloading. When not in use, the stage is raised and the shaft left open to traffic. When necessary, the backs of the plats are supported with timber, as in vertical shafts.

The appended table gives the dimensions of the plats in use on the principal

mines.

Dimensions of Plats.

No. of Mine,

Name of Mine.

Locality.

Length of Shaft.

Ft. In.

Width.

Feet.

Height.

Feet.

Length.

Feet.

Great Boulder Proprietary

Kalgoorlie

Great Boulder Perseverance

Oroya Brownhill

Associated

13 (a)

Kalgurli ...

South Kalgurli

Ivanhoe ...

Golden Horse-Shoe ...

12 (b)

Lake View Consols ...

10 (c)

Sons of Gwalia

Leonora

Great Fingall

Cue

(a.) Graded to 10 ft. at back. (b.'l Graded to 7 ft. at back. (c.) Underlay shaft.

West Australian Mining Practice

Chapter Vi Mine Development

Distance between Levels — .Crosscuts and Drives — Sampling — Boring and Firing — Winzes — Rises — Costs — Timber ing Levels — Leading Stopes — Framed or Post and Cap Sets — Stull Timbering — Stull and Post — Saddle back — Rafter Timbering.

The term ‘‘Development” is taken to signify the work done for the purpose of ascertaining the extent and value of the ore-bodies in a mine, and the arrangement of roadways whereby the ore may be expeditiously trucked to the shaft for hoisting. Under this head are included crosscuts from the plats; the drives opened along the line of lode; winzes, and rises. The shaft-sinking and plat-cutting are not included, as they may be regarded more in the light of per manent works; they are designed both in construction, and in their position in regard to the lode, to outlive the mine. Drives, crosscuts, rises, and winzes, on the other hand, are of use only as long as ore remains between one level and another, and requires to be taken out. As soon as the ore on any level is exhausted, the drives, etc., have fulfilled their purpose, and are no longer of use; if they caved in or became blocked in any way, it would have no prejudicial effect upon the value of the mine as an ore-producer. Nevertheless, the large mines of West Australia carry out development work in a way that will outlive the present estimated life of the mines by a number of years. This practice, possibly, may result in giving a mine an extended working life, for while the working conditions of the present day place a value to the limit of the ore that may be extracted with profit, the mine may contain large ore-bodies of a grade that, under better conditions, at a later time may be profitably worked.

Distance between Levels. — The practice of late years has been to place the levels farther apart. In the prospecting stage of mining, before the sizes and values of the lodes were fully demonstrated, the distance from level to level rarely exceeded 100 feet vertical, but was commonly between 50 and 70 feet. These short distances were selected for the purpose of testing the lode as it went down. At a later date when it was seen that the lodes were strong and would probably live down, the levels were placed 100 feet apart, and in more recent practice this has again been increased to 125 feet, 150 feet, and 165 feet. In one or two instances levels have been opened at 200 feet apart, but this is quite exceptional. By increasing the distance between levels a greater economy of time and money is effected, as a much larger tonnage of ore can be developed as the result of oj'iening one plat and extending one main crosscut and level. It is found that the mining of ore can be carried on quite safely and effectively with blocks of 200 feet in vertical height. No rigid rule, however, is observed, and the distance is largely determined by the characteristics of the ore-bodies of each particular mine.

Too

West Australian Mining Practice

In some mines where the ore occurs in lenticular masses, the levels, instead of being spaced at regular intervals, are laid out in the most suitable positions for working the main lenses. This system obviates the necessity, that would otherwise frequently arise, of timbering a wide excavation, and the level timbers are further protected, inasmuch as there is rarely any occasion for mining the ore immediately beneath them. To ascertain the depth at which successive levels should be opened it is the practice to sink a winze on the ore-body from the lowest level in progress, and from the information thus gained the position of the next level is determined. In the instances quoted of mines in which the levels are placed 200 feet apart, one of the principal reasons for the practice is that on account of the pitch of the ore- shoots great distances have to be driven from the shaft before the ore is reached, and it is therefore necessary that the largest possible amount of ore should be developed on each level driven, consistent, of course with safety in working. In mines where the ore-bodies occur with greater regularity or are practically unbroken, a distance of from 120 to 150 feet between the levels is found to be the most satisfactory. Here, in addition to the saving in plats and crosscuts, a large quantity of ore is opened up at a minimum cost for driving, while the cost for timbering per ton of ore developed would be greatly reduced.

Crosscuts and Drives. — The main crosscut at any level in a mine is that which is extended outwards from the plat of the shaft, and at right angles to the line of lode. It is designed to intersect the lode and prove its width, and may be extended to exploit other lodes known to exist, or in search of others, and to prospect the country. The crosscuts constitute the main thoroughfare to and from the shaft at each level, and they are usually made sufficiently wide to allow double tracks to be laid for trucking. The main drives open out at right angles from the crosscut at that point at which the lode has been intersected. Main crosscuts are extended along the line of lode for the purpose of ascertaining the length and value of the gold-bearing shoots that the lode Tuay contain, and form the base line whence the subsequent operations of winzing, rising and stoping have their commencement. In the event of the cross cut having exposed other lodes, drives on their course will also be opened, and except in the case of drives on a lode that has already a distinguishing name or number, the lodes are usually numbered in the order in which they are found.

From the drives, crosscuts are run out, at more or less regular intervals, to prove the width of the lode, and are usually extended into the walls to make certain that the limit of the ore-body has been reached in those directions. The intervals between these secondary crosscuts are determined by the knowledge gained in driv ing. The practice is to open them at those points where they may prove most use ful, and if in the subsequent work of ore-breaking it is seen that any crosscut has served its purpose, it will probably be tilled up simultaneously with the stope, and be no more known, except on the office plans.

The main crosscuts are timbered only at those points where the nature of the rock may demand support. The crosscuts off the drives, being of less width and arched at the roof, seldom require any support. The permanent timbering of drives is not proceeded with until after the leading stope has been taken off. From the drives, and sometimes from crosscuts, winzes are sunk to a lower level. Rises are also put up towards the level above.

M Tne De Velopment

The general effect of cross-cutting, driving, winzing, and rising is to cut the lode into blocks of various sizes and shapes, and it is by this system of development that the complete exploration and valuation of the ore-body are accomplished, and the level is then in readiness for stoping ore. As a matter of practice, the development of a level

Fig'. 35. Crosscutting' with Machine Drill.

along the entire length of the lode, as above described, is not carried out in all instances prior to opening stopes. The stopes may be started after the drive has been extended some distance from the main crosscut, and after a rise or two have been put up, the work of development and ore-breaking may be carried on simultaneously.

West Australian Mining Practice

In extending crosscuts from the shaft, and drives from the crosscuts, the floor is graded to slope towards the shaft, the incline in the drives being a little steeper than that in the crosscuts. The object of grading is partly to drain off to the shaft any water that may be found, but more particularly to afford facility in running- loaded trucks from the working faces to the plat. The grade of the track is partly determined by the weight of the loads that will traverse it.

Driving and cross-cutting is usually carried out by contract at a price per lineal foot, varying, of course, according to the hardness of the ground and the dimensions of the drive or crosscut. Where machine-drills are used it is found, both in lateral as well as in vertical development work, that it pays to carry a fairly wide face in working, thus giving an opportunity for boring holes to the best advantage. In a narrow drive or crosscut there is little or no chance for holes to be placed other than in a straight line with the direction of the excavation, and often the ground is broken only by the use of an excessive amount of explosive. The extra amount of shovel ling and trucking that will be necessitated by keeping a good width in the working face is not material.

The driving of the main crosscut is extended for some distance as soon as the plat has been cut, and before the opening-out sets have been put in place, so that no injury may be done to the timber by blasting. In instances where the plat sets have to be at once put in ]3lace to support the ground a strong barricade of poles is used as a shield. Later, when the crosscut has been sufficiently advanced the barri cade is erected in the crosscut. For single track crosscuts the dimensions are 6 feet wide and 7 feet high within any timbering that may be necessary; for double tracks the measurements are 8 by 8 feet. The main drives along the lode are rarely less than 6 feet wide and 7 feet high within timbers, and where double tracks are re quired the width is increased to 10 feet. It may be pointed out that it is always advantageous to carry the height of long crosscuts and drives to eight, or even nine feet, as the better ventilation thus afforded more than compensates for the extra cost of the larger excavation.

An economy in time and an increase in footage driven per month are effected when at least two faces are available for the use of one machine-drill, so that as soon as one face is bored and fired out the second can be attacked. With this alternation the drill is kept constantly at work, with the exception of the time required for setting up, pulling down, and moving from one face to another.

Sampling. — During the work of development, the rock exposed after each firing is carefully sampled and assayed. As the crosscuts are extended towards the lode, or are exploring beyond it, the sides of each cut are sampled to ascertain if any vein of ore has been passed through ; samples are also taken from the drillings from one or more of the back holes. If at any point good values occur, the place is re-sampled ; and if the results warrant it, a drive will be started off the crosscut.

As drives follow the course of the lode, sampling is usually confined to the face of each cut ; in most instances, however, before the drill is pulled down after boring the face, holes are bored into the walls, and the drillings sent up for assay, and the sampling is done in sections of a foot or more. The object of boring holes into the walls is to ascertain if outlying bodies of ore exist beyond the apparent limits of the lode that is being followed.

lyfTNE DF.VELOPMENT

During the course of working, the winzes and rises are subjected to the same close examination and testing, and in all cases, in addition to the face samples, bulk samples are taken from the trucks as they are loaded and brought to the plat. Under this system every crosscut, drive, winze, and rise is tested in sections not exceeding 5 feet, and sometimes at shorter intervals. Tlie results are recorded on the assay plans for future reference. Full details of the methods of sampling are given in Chapter XII.

Fig. 36. Showing'Machine in position for Drilling.

Boring’ and Firing. — The positions of iioles in a face, and the order of firing, vary as greatly in drives, etc., as in shaft-sinking. The variation in position is due, in a great measure, to the nature and stratification of the rock, which also affects the quantity of explosive used per foot of advance at each firing. The consumption of explosive per foot, and the average advance made at each firing, is shown in the table on page 107. A few diagrams showing the positions of drill holes and the order of firing are also given, and to these reference may be made.

Fig. 37 shows the face of a drive in rock of average hardness, where 14 holes are required. Nos. 1, 2, 3, and 4 represent the holes forming the “cut”; from the

West Australian Mining Practice

direction of the arrows it will be seen that they converge inwards towards a common centre; they are fired simultaneously in the first round, with the result that a cone- shaied hole is formed in the face to a depth of about 5 feet. The next round would comprise Nos. 9, 10, 11, 12, and 13, to break up the bottom of the drive; and the third round, comprising Nos. 5, 6, 7, 8, and 14 would complete the firing by bringing down the back and shoulders.

Fig. 38 shows the face of a crosscut in moderately hard rock, but which is likely to break more easily than that of a drive, as its direction is across the strike of the country. In this instance the most noticeable point of difference is the posi tion of the ‘‘cut” holes, four in number. The advance here made is 6 feet, with an ex penditure of 12.86 lb. of explosive per foot, as against 5 feet, with an expenditure of 12.54 lb. explosive in the drive.

Fie'. 37.

Showing' position of holes in face of drive. RocK of average hardness.

Fie'. 38.

Showing position of holes in face of crosscut. Moderately hard rocK.

Fig. 39 shows a method adopted in both drives and crosscuts. The rock is of moderate hardness. The holes D, D, D, D, represent the cut, and are first fired. The two side holes E, E are fired only if it is thought that too great a burden has been placed on the “cut” holes. In the next round, holes B, B are fired together with those marked F, F. In the three back holes, A, A, C, the latter explodes first, followed quickly by the A, A holes. In the last round, the bottom hole G goes first, followed by the two H, H holes. The advance in this example is 6 feet with 9.17 lb. explosive per foot for drives, and 8 feet with 6.87 lb. explosive for crosscuts.

Fig. 40 shows a totally different method of placing holes. This is in a crosscut, with the bedding of the rock inclining towards the face of the crosscut. A total of 18 holes are bored in three vertical rows of six each; the direction of the holes is downwards — with the exception of the back holes, which are inclined upwards in order to maintain the height of the working. The rounds are fired in the order shown by the numbers in the longitudinal section in which the three bottom holes, forming the “cut” are fired first. In this instance, the advance made is 8 feet, with 12.17 lb. of explosive per foot of crosscut.

Mine Development

Figs. 37, 38 and 39 represent “centre” and “diamond cuts,” and Pig. 40 a “stope cut.” Slight variations of these methods are to he seen in different mines, and in rock of harder nature, bnt with the exception of tlie “stope cut” the principle in all is the same, namely a “cut” in the solid face. This is effected by boring holes to a common meeting point, so as to concentrate the force of the explosion; the sides, back, and bottom are thus broken inwards towards the cavity made by the cut.

Upon the skilful boring and complete breaking out of the cut depends the success of the miner. If an error is made by giving the holes too heavy a burden to break, or if they have not been brought close together at the inner point, much trouble ensues, as well as a greatly increased expenditure of explosive. Only by

Fig'. 39. — Showing method of placing' holes in drives and crosscuts

in moderately hard rocK.

practical experience can the art be learned of placing holes to suit the character of the rock. The first-class miner is quick to note and appreciate these points, and plans his work to suit them. Not only is the work performed more quickly and neatly, but less explosive is expended. The careless or indifferent miner trusts to the power of excessive loading of the holes rather than skilful placing, to attain the desired result.

West Australian Mining Practice

The time elapsing between firing and resumption of work ranges from ten minutes upwards, according to the ventilation at the working face. As the broken rock is scattered along the drive by the force of the explosion, there is no necesssity, as in shaft-sinking, to clean up after each round is fired. When faces at two different points are available, shovellers clean up the broken rock from the face fired out, while the machine men are boring the other face. The system of alternate faces, as already pointed out, adds very considerably to the number of feet that can he driven by one machine per month.

Showing Position of Holes in Face.

Fig. 40. Showing Face Bored Out.

It will be seen that the dimensions of drives and crosscuts vary slightly in the several mines. The average is 7.12 by 6.20 feet for drives and 7.25 by 7 feet for crosscuts, not including those designed for double tracks. From the figures supplied in regard to feet advanced at each firing-out, the average is 6.22 feet for crosscuts and 5.29 for drives. This is in favour of the crosscuts, which, besides being generally of wider dimensions than drives, have the advantage of breaking more freely to lines of jointing. The drives, following the strike of the country, would be more difficult to break. It is also shown that the crosscuts, besides having a greater footage of advance, require less explosive, the average quantity used per foot of advance being 9.45 lb. as against 10.66 Ih. per foot for drives. The above averages include all the mines dealt with in these pages, hut it may be of interest to show the effect of harder country, and increased costs in wages and stores, in the cases of two distant mines, as compared with the conditions obtaining at Kalgoorlie.

Mine Development

The accompanying table shows the distances between levels, the dimensions of drives and crosscuts, and other detailed information: —

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West Australian Mining Practice

In the case of the Kalgoorlie mines, taking the available figures, the distance advanced at each firing is: Crosscuts 6.52 ft.. Drives 5.50 ft.

In the two mines outside Kalgoorlie, viz., Sons of Gwalia and Great Fingall, the figures are: —

Feet advanced each Firing.

Lb. of Explosives per foot.

Total average cost per foot in shillings,

Great Fingall.

Sons of Gwalia.

Great Fingall.

Sons of Gwalia.

Great Fingall.

Sons of Gwalia.

Crosscuts

4'5

9'37

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Drives

4'37

10'27

It has not been possible to obtain a segregation of the total costs of all mines on a common basis, but the following examples will serve to show some of the methods : —

Great Bouldee Persevebance Mine.

Drives.

Crosscuts.

£ s. d.

£ s- d.

Wages and Contracts, including Trucking ...

Proportion of Power, Compressed Air, and Haulage ...

0 10 10

0 10 11

Explosives

Tool Sharpening

Drill and Air Line Maintenance...

Candles, Steel, Sundry Stores, and Assaying

Proportion General Expenses, Superintendence, and GeneralExpenses ; General Repairs and Maintenance

Total Cost per foot ... . ...

£l 6 4

Golden Horse-Shoe.

Wages.

Stores.

Total Cost per Foot.

Crosscuts

£3 0 0

£0 14 93

£3 14 9-3

Drives

£l 13 4-3

£4 2 3-7

Less Cost of Ore Debited to Stoping and Stoping Cost

£l 9 11-4

£0 9 1-4

/I 19 0-5

Net Cost per Foot

£.0 19 0

£l 4 2-9

£2 3 3-2

Mine Development

These costs include proportion of the following:— Superintendence, Wages (Miners, Bracemen and Platmen), Assaying, Hoisting, Explosives, Timbering, Com pressed Air, Machines, Drill Sharpening, Pumping, Candles, and General Mining.

Lake View Consols Mine.

Drives.

Crosscuts.

S.

d.

£

S.

d.

Labour and Salaries

Explosive

Power

Repairs ...

6T7

Candle, Steel, Sundries, Assaying, and Pumping

5'44

Total cost per foot

Winzes and Rises. — “Winze” and “Rise” are practically smonymous terms, save that the former applies to a working proceeding from an upper to a lower level, and the latter to a working carried up from a lower to an upper level. The workings usually follow the lode, with their length parallel to its strike, though exceptions to this practice are found when an irregular occurrence of ore is followed. Primarily this form of development work is undertaken to test the extent and value of an ore-body under or over a level, and it is the practice in some mines to sink winzes to the depth at which it is intended to open a lower level before the latter has been driven. On most mines on thee fields winzes are sunk a little more than half way, the connection being effected from the level below by means of rising. Winzes and rises also play an important part in the ventilation of a mine, and as points from which successive stopes can be commenced in the blocks opened up.

Wimes. — The distances at which winzes are placed apart in a level vary according to the occurrence of the ore-shoots. In a mine where the development is considerably in advance of ore requirements, the winzes in the lowest level may be at distances of 300 or 500 feet apart, and sunk merely as a guide for future working. In the upper levels where ore-breaking is in progress, or about to be commenced, connections by means of rises and winzes will have been opened at intervals ranging from 125 to 150 feet apart. This is the practice in mines in which the lode is fairly regular in occurrence; but in others, where the ore is deposited in less regular form, no stated distance can be laid down. In these last-named cases, a winze is sunk at that point of a level at which it is calculated to be of most use, both in testing the ore below and in forming a point for subsequent stoping; and it is in dealing with an irregularly shaped ore-body that the course of a winze is not always maintained at the one angle, for the reason that it is usually advantageous to follow the lode.

The dimensions of winzes vary from 6 by 4 ft. to 8 by 5 ft. within timbers. They are usually sunk off the side of the drive, so as not to interfere with the traffic or become a possible source of danger to workmen passing. For the first

West Australian Mining Practice

few feet in depth, a winze is closely timbered with sets of either sawn timber or round logs. Two or more sets of logs are laid above the level to form a collar on which to set the windlass. Eor the remainder of the depth, however, timber is not put in ex cept at those points where the ground may require support. When this is found to be necessary, bearers are hitched into the ends or sides of the winze and as many sets of timlier built up from them as may be required.

As a rule, winzes follow the foot-wall of the lode and conform to its undulations, if any. On the bearers underfoot, a bucket or skip road is laid, and to one side ladders are fastened for the use of the men. In vertical winzes the

Fig. 41. -Showing Winze SinKing with windlass and bucKet.

bucket road is not, of course, required. The last 25 or 30 feet of ladder-way consists of a chain ladder which can be drawn up when firing takes place. The boring is done by machine-drills from spreader-liars fixed across the winze, and the system of placing the holes and of firing is on the lines of that adopted in shaft-sinking.

Ventilation does not present any special difficulty, as the smoke from the explosions rises and is carried away by the current of air passing along the level above. It is usually possible to resume work within 20 to 30 minutes of firing, and

Mine He Vet.Opm Ent

if required, compressed air is used to dispel any remaining fumes. Firing is usually arranged to take place just prior to the time for ceasing work for “crib” or at change of shift, and this generally allows ample time for the winze to cool down.

The removal of the broken rock is effected by Imcket and windlass in the early stages of sinking; sometimes this method is adhered to for the whole depth of the winze. It is not, however, economical for depths exceeding 20 or 30 feet. Beyond that depth two men would be required on the windlass, and the cost would necessarily lie increased. The more modern practice is to use small hoists operated by compressed air, and these are brought into use when a depth of 20 or 30 feet has been reached.

Various makes of air-hoist have been introduced, and within quite recent times a small or “baby” hoist has come into favour. Its strength, combined with small size, and the fact that it is clamped to, and operated from, the spreader-bar of a rock-drill, makes it a very efficient hoist and one that occupies little space in the level from which the winze is being sunk. It is operated by one man, and can hoist a load of 4 cwt. with ease.

Fig. 42.- Winze SinKing with Air Hoist.

The accompanying sketch shows a device for self-tipping kibble suitable for use in sinking an inclined winze.

West Australian Mining Practice

At the Bellevue Mine, Mount Sir Samuel, a prospecting winze was sunk following the convolutions of the lode; and. owing to the constantly altering angle of inclination, it was found impossible to use a skip running on wheels, as it would frequently leave the rails. A kibble or bucket with runners sliding on the rails was substituted with satisfactory results. The action of the device is as follows: — As the full bucket is hauled up, the projecting horns at the hack upper end engage and slide along the slightly elevated 18 by 6 in. pieces till they pass the slots. The bucket is then lowered, the horns catch and the mouth of the bucket is depressed, discharging

the contents. To lower, the bucket is hauled up till the horns pass the upper end of the tumblers, which, being pivoted at a point nearer to one end, always remain vertical when not in use. On again lowering, the horns catch the tumblers and turn them over in the second position shown on the sketch, where they are prevented from further turning by projecting pins. The horns are now guided over the slots and the bucket continues down the winze. The tumblers resume their position of equilibrium ready for the next operation.

Mine Development

The following segregation of costs of winzing have been snp]hied by three of the mines quoted above: —

(Ireat Boulder Perseverance.

Cost per foot.

S

d.

Wages and Contract, including Trucking

Proportion of Power, Compressed Air, and Haulage

Explosives...

Tool Sharpening

Rock-drill and Air Line Maintenance

Candles, Assaying, Steel, Sundry Stores

Proportion Supervision, General Expen.ses, and General Repairs and Maintenance

/5

Golden Horse-Shoe.

Winzes.

Wages.

Stores.

Total Cost.

£ s. d.

£ s. d.

£ s. d.

3 18 L7

Less Cost of Ore Debited to Stoping at Stoping Costs ...

0 4 8'5

0 1 5'2

£3 13 5'2

£l 0 27

£4 13 7 9

These costs include proportion of supervision, wages of miners, brace-men and platmen, assaying, hoisting, explosives, timbering, compressed air, machine repairs, tool-sharpening, pumping, candles, and sundry supplies.

Lake View Consols.

£ s. d.

Labour

Explosives

Power

Repairs and Maintenance

Candles, Steel, Oil and Sundries, Sampling and Assaying, Pumping and Bailing

£5 6 10

The cost of sinking winzes in eleven mines is shown by the following table, together with other information. From the figures given it will be seen that the aver age amounts to £4 15s.

West Australian Mining Practice

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crT

o

o

O'

Co

Co

00 d

0 5'

-p

-p

-p

-p

Ln

C_n

Ft.

0 5’

o o o

to

o

o

Cn p-

o

O

Lw

O

O

O

to CO

o o

o

O O '

O

o

Uj

O

to

o

o

-p

lo

o

o 3

5'

5’

d

o

d

o

o

2:

(u

O

ft

S 3

N Q 5

C/3 3 O

5

3 cr

5d H

ft

ft

ft

ft

.

Ui

-P

-p

-p

-p

u

Ui

OjfS

C/)

Lr

Cn

Ln

"vj

Ln

ft

vO

Ln

0 o.

'vl

-J

?0

o

o

Cost of Winzing.

Mine Development

7?5e5._The distance between rises is the same as that between winzes, as they are designed to connect and provide a way from level to level. The dimensions are also similar to those of winzes. The height to which rises are carried up varies considerably in different mines. In some the customary height seldom exceeds 25 feet, while in the majority of cases the practice has varied from 40 to 60 feet, or even greater. In recent times, however, a General Rule under The Mines Regulation Act, 1906, ordains that — “In all vertical rises, and rises not more than an angle of 30 deg. from the vertical intended to be more than 30 feet in height above the recognised back, the box method of rising shall be adopted, and no such rise shall be constructed to a greater height except by such system. ’ ’ This rule has, therefore, set a definite limit to the height of the unboxed rise, and the heights shown in the appended table are those to which experience has proved it to be safe and economical to construct unboxed rises prior to the enactment of the regulation above quoted.

The construction of a rise is generally cheaper than that of a winze; the lower cost is due chiefly to the fact that the broken rock falls to the level instead of, as in a winze, having to be hoisted in buckets. Ventilation is also assured where machine drills and compressed air are used. The process of boring and firing is conducted on the same principle as in winzes. As the rise advances, strong bearers are wedged into hitches cut in the sides of the rise, and on these bearers a stage is laid for the workers to stand upon. The machine is set up with its bar rigged across the rise against the sides, and the stage carries the weight of the men and tools. The machine-drill, steel, and tools are hoisted into position by means of blocks and tackle suspended from a bearer placed high up near the face, thus minimising the labour of hoisting.

In the practice of some mines the machine is not sent down to the level on the occasion of every firing, but only when it becomes necessary to send it to the shop for overhaul and repair. In these instances pent-houses are put in at every 20 feet, and cover about three-quarters of the area of the rise. The openings are arranged on alternate ends to assist in creating a current of air. When boring has been completed the machine is stowed away beneath a pent-house and covered to protect it from possible injury. In other cases, only the bearers are left standing, and all tools and stage-boards are sent below. As the stage-bearers are set at intervals of about 5 feet apart, the ascent of the rise on the resumption of work is made comparatively easy. It is found that an interval of from 30 to 40 minutes after firing is sufficient for the smoke to be dispelled; but usually the interval is greater, as more than one face is provided for the machine, and the rise has ample time to cool down. On ascending to resume their work after firing, the men draw up the air-hose and dis pel any remaining fumes by means of compressed air. The same means is used for ventilation while the work of setting up the machine is in progress. During the time of boring, the exhaust from the machine keeps the rise cool and well ventilated.

The box-rise referred to is seldom adopted, and then only if it is desired to put up exceptionally high rises. By this method the rise is divided into three compart ments (Fig. 44), and the dimensions of the rise must necessarily be greater than those of an unboxed rise. The compartments provide for a ladder-road at one end of the rise, a centre compartment for holding the rock broken in firing, and a narrow air-way at the other end. The centre compartment requires to be close-lined to hold the rock; it is closed at the bottom and fitted with a chute for loading trucks, and may, in fact, form a temporary ore-bin.

West Australian Mining Practice

Filled with '

Airway

' Ihi

Fig'. 44. Showing construction of Box Rise.

Mine Development

Erom this bin a certain proportion of rock is drawn off after each firing, enough lieing left to keep the box full and so to form a firm pillar of stone, upon the top of which the workmen stand. After each cut the framing is added to, so as to bring the top within working distance of the face. The opening of the ladder-way and the small air-passage are assumed to create a splendid system of ventilation, but as the air current naturally short-circuits immediately across the top of the box, the men 5 or 6 feet above do not experience any great benefit from it. Were it not for the exhaust from the machine their heads would remain in an up})er stratum of hot air. As far as ventilation is concerned, the plan looks better on paper than it works out in prac tice. The only advantages it possesses are, a firm pillar of rock for a working stage, and a permanent ladder-way for ascent and descent. The cost of constructing a box rise is obviously a heavy one, both in time and material, and this is accentuated by the fact that it is not a permanent work, but has to be pulled out when the rise is completed.

As regards cost of rising the figures supplied by eleven mines are given in the subjoined table, with dimensions and other information. The average cost per foot of rising works out at £3 18s. 7d.

Cost of Risi.vg

Xo.

Name of Mine.

Locality.

Dimensions.

Distance

between

Rises.

Height to which usually carrird.

Time between firing and resumption of work.

Cost

per foot.

Great Boulder Proprietary...

Kalgocrlie ...

Feet.

Feet.

Feet .

Minutes.

£

s.

d.

0 ie)

Great Boulder Perseverance

7 X 5 (a)

(b)

Oroya Brownhill ...

(cl

Associated

!0

8 5 (/)

Kalgurh ...

(&)

5 (ft

South Kalgurli

|6)

30 to 60

I vanhoe ...

Golden Horse-Shoe

No rising dont

—

—

—

Lake View Consols

( 100

J 150

9-88 (/)

SonsofGwalia

Gwalia

j 100*

[d)

O' 85 (e)

Great Fingall

Day Dawn ...

(b)

[a) 10 feet x 6 feet for a box rise. (b) Depends on ore-bodies. (c) Depends on distance from air-way.

(li) Two faces. Some hours elapse. (e) Includes wages and stores. (/) Includes wages, stores, and proportion of administration and general expenses.

*In the south end of the mine the distances are quite irregular, the rises being put up on the north end of the shoot.

West Australian Mining Practice

The following table shows the method of segregation adopted on two of the mines : —

Great Boulder Perseverance.

Cost per Foot.

£ s. d.

Wages and Contracts, including Trucking

Proportion of Power, Compressed Air, and Hauling

Explosives ...

Tool Sharpening

Rock-drill and Air maintenance

Candles, Steel, Sundry Stores, Assaying

Proportion Supervision and General Expenses, General Repairs, and Maintenance

Total Cost per Foot

Lake View Consols.

£ s. d.

Labour and Salaries

2 14 4 66

Explosives ...

0 y 4 73

Power

0 16 263

Repairs and Maintenance

0 5 8 52

Candles, Steel, Sundries, Assaying, Pumping

0 7 1'34

Total Cost per Foot

12 9'88

Timbering Levels. — Owing to the firm character of the rock in most of the larger mines of the State, it is seldom that the drives and crosscuts require timber for support. Occasionally it may hapiien that at some point in the hack of the level the rock exhiliits signs of weakness and a liability to break away, and then it will re quire to be supported, but this is of comparatively rare occurrence. When, however, the work of ore-breaking is to commence, the timbering of a level becomes a necessity. The levels are driven on the course of the lode, and consequently the back is in ore; when this is broken out a false or artificial back or roof is required, and is provided by means of timbering. The necessity for this is due to several reasons — the principal one is that the ore is kept overhead and can be loaded into trucks at a minimum expenditure of labour; the level has also to be kept open and free for traffic without danger to passers by, and to afford means whereby the stopes can be filled with waste rock as the ore is drawn from them. If a drive is in ore for its whole length, it will be timbered throughout; if not wholly in ore, timber will be put in only beneath those sections in which stopes are to be opened.

Mine Development

Leading Slopes. — Before any timber is put in place, the back of the level is cut away in what is known as a “leading stope” (Fig. 45). This is, practically, a series of slices taken off until the back is from 14 to 20 ft. above the track on the level, or from 7 to 13 ft. above the top of the timber to be put in. This is done to provide room for working and to protect the timber from injury when blasting down the ore in the

Fig. 45. — Leading Stope.

stope. The ore broken out from the leading stope falls on to the level, and is removed by shovelling into trucks; but after the timber is in position, the ore from subsequent breaking falls upon the timber and is run through chutes into trucks as required. When the leading stope has been taken out the level is ready for timbering.

West Australian Mining Practice

Timbering. — Four methods of timbering are in use in the principal mines of the State, namely — Framed or Post and Cap Sets, Stull, Rafter, and Saddle-back. Of these, the first two are those commonly in use, and the last two are employed for special purposes only. In some mines one method alone is found to he sufficient throughout the mine; while in others two, or more, styles are brought into use. These variations are caused by the special features of the ore-body to be mined. The timber selected for the purpose is round salmon gum of from 12 to 18 inches in diameter at the small end. This species has been found to be more suitable in the matter of strength and durability than other native timber, such as jarrah. It serves its purpose best when })ut into the mine while green; sticks that have become dry on

Fig'. 46. Timbering' Level. Framed or Post and Cap Sets.

the surface do not ap]ear to last so well, and are apt to become short in the grain, and to break when i)ressnre comes upon them. All bark is removed before the timber is sent below, partly to prevent the accumulation of litter that would ensue on its peeling off, and also for the better preservation of the wood. The bark is particularly susceptilde to fungoid growths, and subject to rot from accumulated moisture. The cutting and fitting of the timber is done on the surface, and, in the case of framed or post and cap sets, s])ecial care is taken to make true and close-fitting joints. Each set bears a distingnishing mark, and each unit of the set is numbered to fit into the particular seat made for it.

Mine Development

Framed, or Post and Cap Sets. — Each complete set consists of four pieces: — two posts, one cap, and one sill, or sole-piece. The diameter of the posts and cap would be from 12 to 15 in., and of the sill 12 in. The dimensions within the set-timber are: — posts 7 ft., cap 7 ft., sills 714 ft. or longer. The posts are slightly inclined inwards at the top, so as to provide greater support to the cap. The sill is added Hat along its lower side so as to give it a true bedding on the rock; in narrow lodes it is left sufficiently

Fig'. 4 7. — Timbering' Levels. Frame or Post and Cap Sets.

long to enable its ends to be hitched into the walls. The sets are placed 5 feet apart, centre to centre, along the level, and between each set studdles, or distance pieces, are placed horizontally from post to post to afford lateral support. The foot of the post rests upon the sills in places cut level to receive them, and are let in one inch

West Australian Mining Practice

or more below the surface of the sill. The upper end of the post, and the end of the cap, ai’e cut to a close-fitting joint designed to take the full strength of both pieces and to resist pressure from the walls on either side. The accompanying illustrations (Figs. 46, 47, and 48) clearly show the special method of jointing. On the line of junction between post and cap a shallow mortise is cut to receive the studdles — the length of the mortises being divided between the post and the cap so that the end of the studdle has a bearing upon each of the two pieces. The studdles consist either of round poles or of sawn timber, and are fitted tightly into the mortises. The ends of the ca}) are cut fiush with the outside line of the post. In instances where the end has been allowed to project for some inches, disturbance and breakage of the joint

Fig'. 48. — Complete Framed or Post and Cap Sets, showing' also Ore Shoot and

Double TracK in Level.

have been occasioned by iiressure falling upon the projecting end. In putting the set in place in the level, a trench is carefully cut out across the bottom for the sill to lie in. When it is necessary to blast the rock for the trench, small “pop” charges are fired from holes bored either with a small rock-drill fastened on a tripod, or with air hammer drills. Care is taken to have the sill bearing evenly along its whole length and, finally, when the complete set is in position, it is well rammed and ballasted with small rock. The sills are laid on the grade decided for the track, and the trim ming of the bottom of the drive is usually necessary to free it from humps and hollows.

In narrow lodes where the drive has followed the contour of the foot-wall,

Mine Development

abrupt turns are commonly met with. These may be straightened out to some extent by blasting away the angles, and at least sufficiently so to permit of the track being brought round on a wide curve. The sets of timber are carried round the curve by allowing a “lead” to one side or the other, with tlie result that the posts are brought a little closer together along the inside curve. In lodes of greater width this difficulty is not so frequently experienced, and it is possible to carry the timber forward along straight lines for considerable distances.

Where the tiinbering of a drive has ore on lioth sides, the intervals between the posts are closely lathed to hold the filling put in after the ore is extracted. This greatly increases the stal)ility of the sets. Over the cap i)ieces, poles 3 to 4- inches in

Fig'. 49. — Stull Timbers showing Pole Lagging.

diameter, and 10 to 12 ft. in length, are laid closely together to form a bed, through which at certain distances chutes will have been constructed for loading the ore into trucks. The filling is placed to act as a cushion to protect timber against injury from falling ore during subsequent blasting operations.

It may happen at times that the overburden, either of ore or filling, resting upon the timbers, becomes too heavy for some unit in the set to withstand; a cap may show signs of cracking, or a post signs of splintering, or, owing to some extreme lateral pressure, one or several sets may be thrown out of plumb. If the cap-piece is only slightly fractured, it may be strengthened by placing a false set underneath it.

West Austealian Mining Practice

Sets that may have l)een thrown out of plumb — in which case the studdles will either have sagged or snapped in two — can sometimes be straightened up by the use of screw-jacks and held in place by angle-braces reaching from the sill of one set to the cap of the other, through as many sets as may be necessary.

Stull T'uubering. — For convenience this system of timbering may be divided into two sections, “Stulls” and “Stulls and Posts.” The first of these two methods is frequently adopted in timbering drives in which the lodes have strong, well-defined walls, not exceeding 12 to 14 ft. ai)art; the second is used for wider spaces in which the stull-]fieces require to be reinforced with posts. The stull-ifieces consist of logs.

Fig'. 50. Stull and Post Timbering'.

having diameters at the small end varying from 15 to 24 in. As in set-timbering, they are not ]mt in })lace until after the leading stope has been taken out. On the foot-wall side of the lode a hitch is cut into the rock at a height of about four feet above the track; into this hitch the foot of the stull is fitted and the upper end is cut to lie fiat against the opposite wall. The angle at which the timber is set across the drive is largely governed by the dip or underlay of the ore-body; in the case of a fiat lode, or a lode dipping at an angle of say 30deg., the stulls in the drives would have an inclination of a little over 60deg., while in the case of a lode nearly vertical in dip the stulls would be set at an angle of about 20deg. from the horizontal. In

Mine Development

practice the stall is set at an angle slightl) greater — measured from the horizontal —than that shown by a line drawn at right angles .to the dip of the lode. By this method the timber presents greater power of resistance against crushing, and there is no danger of the stull slipping from its position once it is securely tightened. The stalls are placed at about five feet apart from centre to centre. The hitches are cut by hand-drilling, or by air hammer drills. A row of holes is bored horizontally close together on a line at the bottom of the hitch, and one or more holes are bored

from above, slanting inwards and downwards to junction almost with the bottoms of the horizontal holes. These are fired with “pops” of explosive, and a good hitch usually results.

The depth of a hitch is governed by the nature of the rock; where the rock is of a dense, tough nature, not inclined to flake off, an inch or two affords ample holding ground. The lower edge of the stull is added flat to sit comfortably in the hitch and

West Australian Mining Practice

to prevent any tendency to roll. Care is taken to see that no loose or “balky” rock exists where the hitch is to be cut, and any unsoniid pieces are broken off. The same care is exercised in regard to the ground on the hanging-wall, and here there may be a decided tendency in the rock to flake off after exposure to the air, hut with long stulls set at a safe angle there is practically no danger of slipping. No studdles or distance pieces are required between the stulls, as their weight and pressure against the walls is sufficient to withstand any lateral thrust. The stulls are covered with poles to form a floor to the stope, as in set-timbering. In narrow lodes the stull system has been found sufficiently strong, and it possesses the advantage of being less costly than set-

Fig. 52. Rafter Timbering', showing' Ore Chute and TrucKs.

timbering, and offers no difficulty at a subsequent time, when a stope is being beaten through from the lower level. It is doubtful, however, if under severe pressure it is capable of sustaining as great a burden as the set system will carry.

Stull and Post. — This method combines most of the best points of the two systems already described, and it is suited for wide s])aces. As in the foregoing method, hitches are cut, but the stull-piece is not necessarily ]iitched at so steep an inclination. In addition to this, posts are placed at both ends of the stull and at such intervals along its length as its span, or the estimate of the weight it will have to support, may require. The lower side of the stull at those points at which posts are

Mine Development

to junction, is added flat, and the head of the post is trimmed to form an accurate close- fitting' joint; but there is not the same costly work required for this as is demanded for the joints of set-timbering.

Saddle-Back Timbering . — This system is adopted in a few instances in which the width of the lode is too great for stalls, and where set-timbering is not considered suitable. Owing to its form of construction, it is calculated to he able to withstand excessive pressure. It is, in fact, a duplication of stalls, the feet of which rest in hitches cut in both walls of the lode, with the top ends meeting in the centre over head. With the timber pitched at an angle of about 45deg. this method is undoubtedly of great strength. The stalls are lagged over with poles to form the stope floor, and, from the form of the saddle-back, the maximum pressure of the overburden is thrown against the walls. The jointing of the stalls at the apex demands considerable care.

Rafter Timbering. — This system might, perhaps, he properly classed as a variation of stull-timbering, and is commonly used in mining lodes with flat underlay. Where it has been adopted it has been found effective and not expensive. The drive is usually carried along on the foot-wall side of the lode, though in many cases it is partly kept in the foot-wall country. This having been done, and the lode having been stoped away to the height of a leading stope, stalls of 10 feet or greater length are placed as nearly vertical as possible along the open side of the drive from which the ore has been extracted. The distance between stalls is about five feet from centre to centre, and they are lagged on the lode side with round poles, or split slabs, against which the stope-filling is closely packed. With the drive cut well into the foot-wall, the feet of the posts are set upon solid rock and are not disturbed when the ore under foot is mined from below. The system presents great resisting power against pressure, owing to the timber standing almost upright and the unsupported portion of its length being not greater than the height of the drive. It is not costly, as no cutting or fitting of joints is required. An objection urged against it is the dead work of cutting the drive in the wall rather than in the ore.

T28

West Australian Mining Practice

Chapter Vii

Ore Chutes And Passes

Construction — Dimensions — ‘ ‘ Chinaman ’ ’ Chute.

T[IE constriTctiou of ore-chutes is undertaken in conjunction with the timbering of a drive over wliich stoping is to proceed. These chutes are structures built in the side and back of the level for the purpose of drawing off the ore that is broken in the stopes. AVith well constructed chutes placed at convenient intervals along a level the ore can })e run into trucks at a minimum cost of labour. Generally speaking chutes do not vary in form, though their position in a level is varied in some degree according to the particular method of stoping that may be practised. They are strongly made of hardwood in frame and lining, having a maximum length of from 4 to 5 feet, with a depth of about 4 feet. They are usually set on the foot-wall side of the drive in narrow lodes, while in wider bodies of ore they may be set on either side, as may be found convenient. Beneath the opening in the side of the timbers in the level, four posts are set up and are firmly secured to the permanent timbers of the drive. On the inside of this frame the bottom and sides of -the chutes are fixed, formed of 9 liy 3 in. hardwood planks. The bottom is sometimes lined with sheet iron to resist the wear and tear of the running ore, or is lagged with small gimlet-wood saplings. These are less costly and are almost as durable as iron. The chute inclines downwards and outwards towards the level, the sides being drawn in until the lip is narrowed sufficient!} to guide the ore into the truck; the lip of the chute projects over the track at a height just sufficient to allow the truck to stand underneath. Above the u])])er edges of the chute, timber is built up vertically until it is connected with the opening from the stope. About 12 or 15 inches from the front of the chute a door is placed to give outlet to the ore as required. Iron doors, 24 by 24 inches, by %-inch, are commonly used, while in some mines only ordinary stopper- boards are adopted. The iron door works in iron guides at either side, and is operated by means of an iron lever. The short end of the lever is connected to a pin in the door by means of a link, and the lever is pivoted on to one of the uprights at the side of the chute, the free end projecting sufficiently to give power to raise the door as required.

The run of ore is regulated by the height to which the door is lifted, and can at once be stopped by releasing the pull on the lever and alloAving the door to drop in its guides. It frequently happens, however, that the door is caught and held open slightly by rocks, and a trickle of fine ore continues. To arrest this the lower part of the chute is furnished with stopper-boards -—pieces of wood laid across the chute, and against which the fine ore is held. The boards are kept in place by means of chocks of wood fastened vertically to the sides of the chute. In many instances iron doors are

Oek Chutes And Passes

not adopted— partly on the score of expense and partly because the more primitive and equally effective stopper-hoards are well adapted to the special circumstances. When ore is to he run into trucks the boards are easily displaced by hand, or by means of a short iron bar; their replacement, to stop the run of ore, is equally simple. Stopper boards possess the advantage of cheapness of first cost, they are easily replaced when broken or damaged, and have no gear attached that can get out of order. The iron door, on the other hand, costs more, and is liable to become unevenly bulged by ore falling against it; when that happens it will not run freely in its guides, and causes trout)] e. In some instances steel portable chutes are used with economical results.

Fig'. 53. — Ore Pass and Chute.

The type of chute used varies in accordance with the method of stoping, that may be practised. For flat-hack stopes the chute and the ore-pass, of which it forms the bottom, are fixtures. The chutes are placed at intervals of from 30 to 50 feet along the level, in process of stoping. The passes are constructed of sawn timber or round logs, and are built up in sets as the stope rises, and the filling is then run in. The ore in the stope is thrown into the passes and is prevented from running out on to the level by means of a door, or by stopper-boards. Though the pass and the chute are fixtures the chute may be removed for use elsewhere if the timbers are in good order after the stope has been depleted. With the rill stope the chute is made so that it may be moved along the level in accordance with the advance of the foot of the rill until the ultimate length of the latter is reached; this would he midway between two

West Australian Mining Practice

rills worked from o]iposite ends of a stope. At this point the chnte would become a fixture, and an ore-pass would he logged upwards gradually through the filling.

In the shrinkage system of stoping, the openings in the hack of the level are placed at intervals ranging from 12 to 25 feet apart. The chutes are constructed in the manner already described, hut no logged pass is rendered necessary, as the stope is kept filled with broken ore.

The chutes already described are those most commonly in use. One other kind, known as the “Chinaman” chute, is occasionally adopted in connection with the shrinkage system of stoping, and it possesses some advantages over other forms of

Fig. 54. Ore Chute, Stull Timbers, and Framed Set.

chutes. Fig. 55 gives an excellent idea of its construction and application. When constructing the chute, six hitches are cut on a horizontal line along both sides of the drive, at a height of 5 feet above the track, and at intervals of 5 feet, from centre to centre; this forms a bottom to the chute of from 25 to 30 feet in length. Across the drive, with their ends resting in the hitches, joists of 6 by 8 in. hardwood are fitted, the longer dimensions being vertical for purjmses of strength. Above the joists a double row of 12 by 3 in. hardwood decking is laid so that between them and over the centre of the track, an opening is left 15 inches wide and

Ore Chutes And Passes

for the full length of the chute. Across this opening, at right angles to the decking, loose doors measuring 28 in. long, 12 in. wide, and 2 in. thick, are laid side by side, thus closing the opening to the track below. Prom the central opening, to each side of the drive, a lagging of round poles, 3 inches in diameter, is laid at right angles to the deck planks; these add strength to the decking, and receive all the rough wear and tear produced by falling ore. The ordinary drive timbering is, of course, put in place prior to the construction of the “Chinaman” chute, and the back is poled over in the usual way, except that at intervals of about 25 feet the poles are omitted, so as to form openings for the ore in the stope to fall through on to the deck of the “Chinaman” chute. This opening in the poles lies over the centre of the chute. In the ordinary course of working, the ore from the stope falls and accumu lates upon the permanent timbering of the level. Through the openings provided, the ore passes to the deck of the “Chinaman” chute, and is handled by men em ployed to fill the trucks below. Amongst the ore are pieces which are too large to be thrown into the trucks, and these require to be broken smaller on the chute. This is easily possible as ample room is allowed for the use of hammers between the deck of the chute and the overhead permanent timber; or, if necessary, in the case of extra large or tough rocks, these may with safety be broken by means of small “ pops ” of explosive. In drawing ore from the chute the truck is run underneath, one of the loose doors is lifted, and the ore falls into the truck. The stream can be regulated or stopped at will by replacing the door; and in any case, the ore should not be allowed to pile up on the deck in such a way as to interfere with the regulation of its flow. From the sides of the chute the ore is thrown in by hand shovelling. By reason of the longitudinal opening in the chute the doors can be opened and trucks filled at any point along its length, or, if desired, several trucks can be filled simultaneously. The work is carried out with a minimum amount of labour, and with considerable speed. Access to the chute is gained by means of a short ladder at one end.

The adoption of the “Chinaman” chute affords an easy means of dealing with the over-size pieces of ore drawn from the stope. In the use of the ordinary chute in conjunction with shrinkage stopes trouble is caused by reason of the large pieces becoming jammed at the entrance and blocking the run of ore. They have to be broken where they stand, and the formation of the chute is not favourable to the free use of the hammers; small “pops” have to be resorted to, and more or less damage to the frame and lining of the chute necessarily results. Hence, in these instances, stopper-boards are preferred to the more expensive iron doors and levers. The cost — labour only — of constructing a “Chinaman” chute is quoted at £5, and the timber is available for use at stope after stope until absolutely worn out and shattered. The objections raised against the “Chinaman” chute are not numerous or very serious. One is the extra cost of labour and materials involved; the other objection is that space on the level is uncomfortably limited by the timbers supporting the chute being onh 5 feet above the track, but there is no impediment offered to the trucking of long timbers, machines, or tools to points on the level beyond the chute. To the suggestion that the chute might be placed at a greater height above the track several objections may be offered. It would mean that the permanent timbering of the level would also have to be placed at a corresponding increase of height, and that the increased dis tance between the openings in the bottom of the chute and the top of the trucks would probably cause the spilling of a considerable amount of ore and much subsequent

West Australian Mining Practice

cleaning up and shovelling. It is obvious that an increase in the height of the permanent timbering, whether of sets or stubs, would mean additional cost in materials and labour.

In some instances the “Chinaman” chute has recently been displaced by the steel chutes illustrated in Figs. 56 and 57. The sketches show the whole of the chute, as there is nothing but broken ore behind the timbers. Rocks can be broken in the chute, either by hammer or by blasting with dynamite, without in any way damaging the chute. The lip of the chute is made of %-inch steel, and extends only to the back of the framework. This type of chute possesses many advantages over the “China man.” Two truckers will fill at least twice as many trucks per shift; the necessity for taking off a very high leading stope and the consequent expense of shovelling the extra rock from the level are avoided; stubs can be brought down to a point much nearer the level, where they are more accessible, and can be put in with greater ease; repairs are reduced to a minimum, and the initial cost of the chute is much less than that of the “Chinaman.”

Oee Chutes And Passes

Fig. 55. “Chinaman” Ore Chute.

West Australian Mining Practice

Fig. 56.

Ore Chutes And Passes

— ChMte for

West Australian Mining Practice

Chapter Viii

Stores And Storing

Methods of Stoping — Flat Back — Bill — Shrinkage — Costs — Eelative Advantages and Disadvantages.

During the process of developing a mine by cross-cutting, driving, wiiuzing and rising, as already described, a systematic valuation of the rock passed through, will have been made by means of sampling and assaying. The tonnage of ore exposed and the gold contained per ton, will have been ascertained, and the results recorded, so that the value of the ore in any section, in all drives, winzes, etc., can be quickly ascertained. From these results the points at which stoping may be com menced are determined. A detailed description of ore sampling and valuation, as prescribed in the principal mines, is given elsewhere in these pages, and for the present, attention is devoted only to the method adopted for the economical extrac tion of the ore. It is found that though a lode may carry gold throughout its length and width, and from end to end of the lease or property, yet only in certain sections of its length has it become so enriched as to be capable of yielding a profit under the mining and metallurgical processes of the times. With the advance of knowledge in metallurgy, and the application of mechanical skill, profit can now be derived from a grade of ore which only a few years past, could not have been profitably treated. But even so, almost every mine possesses thousands of tons of ore too low in value for profitable handling under existing conditions, and this must await the further advancement of knowledge or a diminution of the disabilities which at present operate against the mine-owner. Stopes fire therefore opened only on those sections of a level in which sampling and assaying have disclosed the existence of pay-ore. These more highly enriched portions are found to exist in almost all lodes, and are called “shoots of ore,” their longer axis generally making a more or less acute angle with the line of intersection of a vertical plane at right angles to the line of strike. This angle measures what is commonly called the “pitch” of the ore-shoot.

The direction of the pitch of the shoots through the strike of the lode is found to be almost unvarying in its regularity, not alone in any one mine, but throughout the whole of a group of mines in certain districts. There is, however, a distinct varia tion in the sizes of these richer shoots, and in the number that any one mine may be found to contain. One mine may possess one shoot only, but of such size and value as to enable it to return large profits. In others, again, a greater number of shoots may occur, but not large in any dimension, yet sufficiently numerous and valuable to render it necessary to mine and treat considerable quantities of lower grade lode-matter lying between the shoots, which could not of itself be profitably treated.

Both the pitch of the ore-shoots and the dip of the ore-bodies have an important bearing upon the value of the mine, and on the methods employed for working it. In any one group of mines the pitch of the shoot is, generally speaking, in the one

Stopes And Stoping

direction, and this is usually true of the dip, although the angles of dip and pitch may vary in particular mines. Frequently, instead of the enriched ore occurring in regularly defined shoots in the ore-channel, it is found in irregular bodies, these being often met with as isolated masses. Instances are also on record where these lenses of ore are found in an ore-channel with their ends in the direction of the strike of the latter, overlapping and separated by only a few feet. This overlapping occurs in the horizontal as well as in the vertical plane, so that when one lens pinches, another is found by cross-cutting, rising, or winzing, as the case may be. Where the ore occurs in the form of a lode, the lateral limits of pay-ore may or may not be well defined by walls. Where walls do show, pay-ore may generally be distinguished from the country rock by its characteristics of colour and hardness and its general appear ance, all of these being due generally to the greater percentage of siliceous matter present in the ore. In other cases there may be no walls at all, or where “false” walls occur they may not mark the limits of ore. It is then extremely difficult, if not impossible, to distinguish by the eye between profitable and unprofitable ore, the dis tinction resting entirely on the value of the material as disclosed by assay. The limit of stoping operations is determined by the gradual falling away of values in the sides, and, as would be expected, the stopes show no constant width or gradual increase or decrease, but are widened out or narrowed, as the case may require, and as the sampling shows an increase or decrease in the width of pay-ore.

Thus, generally, may be described the chief variations and peculiarities to be found amongst the principal mines of this State. Owing to these, it happens that what is found to be good practice in one mine, or in one group of mines, is by no means suitable for adoption in a neighboring mine or group. Each mine has to be dealt with according to its special features, and a comparison of one with another is of little value. The method of stoping adopted is also largely governed by the characteristics of the ore-bodies.

From the foregoing, it will be recognised that the breaking out of ore for treatment cannot be conducted in a mere rule-of-thumb fashion. It is a department of mining in which much care and judgment have to be exercised unremittingly, and wherein the services of the sampler and assayer are indispensable.

It may chance to be the happy experience of a manager that, along considerable lengths of lode, the appearance of the ore is a guarantee of its value ; even so, every truck load of ore drawn from the stope during each day is sampled, and the average value recorded. If the ore is known to vary in value over short lengths of lode it is the practice carefully to sample and assay every breast or face in the stope. By this method it may, perhaps, be discovered that the best values are along one wall only, and that the ore on the other wall is of low grade; or that a shoot has been penetrated and a zone of poorer ore has to be passed through before another enriched portion of the lode is met with; or may be an intrusion or “horse” of country rock has either split the lode in two or cut it off for some distance along its course. In the case of stopes in the isolated ore-bodies previousl} described, still stricter attention has to be paid to sampling and assaying, and the testing of each face in the stope becomes a necessity. The regular sampling of the stopes is a matter of great importance, and if the sampling is not carefully carried out a quantity of worthless ore may be sent to the mill.

West Australian Mining Practice

Tlie difficulty of distinguishing ore from country rock, in the case of lodes such as those described, has already been pointed out. Consequently, not only have the stope faces to be constantly sampled and tested, but the sides of the stope must be similarly tested, in case pay-ore has branched off behind a mass of low-grade lode matter. The sides are tested by holes drilled horizontally, and this testing is carried out methodically along both sides of the stope, the holes being placed at varying or alternating heights so that the chances of discovering further ore may be increased. The depths of the holes extend to 10 feet, or sometimes further. The drillings — the portion of the rock pulverised by the action of the drill — are carefully collected, those from each section of three feet, more or less, being kept separate, so as to ascertain at what distance pay-ore was met with. Assuming that no profitable grade was found in a hole of 10 feet, but that the assays showed an increase of value as the drill pene trated the side, the practice would be to use a longer drill and extend the hole. It may frequently happen that no discovery of value is made; on the other hand the assays have shown that at some particular section of the hole values have risen to or above the profitable grade. When this occurs a crosscut is driven along the course of the hole and the vein intersected and further examined. Quite a small vein may be found on development to increase into an ore-body of considerable size, constituting a valuable addition to the original stope. Not infrequently the position of the outlying ore-body makes it possible to leave a strong pillar or rib of country rock between the ore-body and the original stope. This is, of course, left to form a support to the overhanging back. If, however, the thickness of the intervening rock is not sufficient to form a safe pillar, it is broken away by blasting and over turned into the main stope. In such circumstances it is the practice never to fill a stope until after the sides have been closely and thoroughly tested in the manner above described. It is within the experience of managers that a stope which at first appeared to be limited, say to a width of 25 feet, has subsequently, and through testing its sides, developed a width of 50 feet or more.

In this description the “stope” will be taken to mean a working in a mine in which the ore standing between two levels, or between the first level and the surface, is broken out, or mined, for the purpose of being sent to the mill. The word itself is believed to be a corruption of “step,” as representing the steps, or benches, formed in underhand stoping. Similar steps, or benches, are to be observed at the present time in any underhand stope, or in a quarry. They are also to be seen in overhand stopes, though of course, in reversed position. The depth of each step would be determined by the length of hole bored for blasting.

Methods of Stoping. — Stoping is usually divided into two main systems — Underhand and Overhand. The distinction between the two is that, in the underhand system, the ore is broken from a level downwards, either to another lower level or to any depth desired ; while in the overhand system, the stope is carried upwards from the level. In the underhand stope the ore would fall to the bottom of the working, and would have to be hoisted thence to the level, unless, as in some cases, it is being broken towards a winze, down which it would fall to the chute in the level below. In overhand stoping, the breaking of ore commences from the bottom of the rise, and proceeds outwards and upwards till the upper level is reached. The broken ore falls to the stope floor, and gravitates, or more commonly is shovelled.

iSTOPES AND STOPING

into a pass ending in a chute at the lower level. It is obvious, that of the two, the overhand stope represents less cost in every way, and that the back is kept free for continuous attack.

In West Australian mining practice, the underhand system is very rarely adopted, and then only in a few exceptional instances, as described later on; con sequently, the practice is almost entirely confined to the overhand system. This, however, may conveniently be divided into three methods, which are in use at the present time, namely: —

1. Flat-back Stopes.

H. Pill Stopes.

3. Shrinkage Stopes.

Sect/on shewing Rill Stopes

Fig. 58. Method:;of Stoping.

Each method j)ossesses its special advantages in economical mining, and is chosen to suit the particular characteristics of the mine and the size and value of the ore-bodies. In some mines the greater part of the stoping will be done, say, on the flat-back system, but there may also be portions of the lode in which the rill system can be more advantageously employed; or, in mines where the rill system is chiefly used, there will be found places where the flat-back stope is brought into use; or again, in a mine where the shrinkage stope is chiefly adopted, there may be places where either the rill or flat-back method is employed to meet special conditions. No manager adheres to a hard and fast rule in this respect, but introduces any one of the three systems best suited to the requirements of his mine, and may supplement that with one or both of the remaining methods, in certain parts of the mine, as circumstances may appear to warrant.

West Australian Mining Practice

In the preceding pages it has been shown, that, prior to opening a stope, the back of the level is cut away to a certain height above the track, and a false back of timber is put in place to form a roof to the level and a floor to the stope. This cut is carried over the whole length of the level, or those portions of it along which it is known that the required grade of ore is standing. The effect of this is that, at the time stoping is to commence, the lower face of the lode stands at a height of seven or more feet above the timbering, the intervening space assuming the appearance of a supplementary drive or level above the permanent one. This is the practice in the majority of instances where the level has originally been driven on the course of the lode, and where its value has been proved to be profitable. Exceptions to this rule, however, occur in consequence of irregularity of ore-deposition or variations in the grade of ore, as, for instance, in the case of a mine in which the ore-bodies are distinctly lenticular, and where a level has been driven immediately beneath the lower portion of the lens. Here, the lower edge of the ore may extend only for a few feet along the course of the level, or it may be found to lie away to one side of the drive. The drive will then have been extended on a line approximately agreeing with the strike or direction of the ore-body, and connection with it will have been made through a series of rises of varying height from the back of the level. This method has the advantage of leaving the sides and back of the level in solid country, and no expensive timbering will be required. The ore, on being broken out, is passed through into chutes formed at intervals in the rises mentioned. It may happen, of course, that the level has not been opened at exactly that point reached by the lowest edge of the ore- lens, and it is found that a portion is lying below the level, but is not continuous to the next level, in fact it may not extend more than 10 or 20 feet below the level. It is in these instances that the adoption of underhand stoping is required for the purpose of extracting the ore under foot.

Another possible exception to the rule may be noted. In this instance the lode has been solid and continuous for the whole length of the level. But, in the course of })utting up rises and in sinking winzes, and by sampling these as well as the drive, it has been ascertained that the required ore values do not extend to the level, or, perhaps, reach it at only one point, and do not continue for any great length along its course. This would mean that for the greater portion of its length the level has been driven in a zone of low values. Under these circum stances it is obvious that unnecessary expense would be incurred by breaking out the ore and replacing it with timber in order to get up to the better-grade material. The practice is to leave the solid back standing above the level and to commence stoping off the rises at the lower edge of the zone. In order to effect this a stope-drive is extended outwards from a rise along the line of the zone ; this is kept well ahead of the stope proper, and practically constitutes an inter mediate level. Between it and the main level a solid mass of low-grade ore is left standing. Through this body of ore rises are extended from the level at certain intervals to form chutes, through which the pay-ore is drawn. Fig. 59 illustrates this procedure.

Although the three methods above-named are all of the overhand style of stope, each is worked in a different way; so that while the general principle is the same the manner of application varies. In each method the lower end, or bottom, of a rise is selected as a starting point, both on account of the facility it offers

Stopes And Stoping

Fig. 59.

West Australian Mining Practice

for breaking the ore and from the fact that tlie rise becomes one of the channels throng’ll ’W’hich residues "ill subsequently be sent down for filling up the excavated portion of the stope.

The widths of the ore-bodies in the mines vary considerably, as will be seen from the table on page 155, in which the mines have lieen grouped accord ing to the type of stope chiefly adopted in each case; though, as already pointed out, one or both of the other methods may also be in use.

Flat-back Slopes. — The procedure in this method is to cut away the ore in a series of slices from the leading stope upwards. The back — i.e., the unbroken lode overhead — is kept in as uniform a state as the nature of the ore, and its disposition to lireak, will permit. The ore is thus cut out, in a more or less regular fashion, from one rise to the next, and over the whole width of the ore-body ; or stopes may proceed simultaneously from two rises, and ultimately meet. The ore is cut away mitil the back may be as much as 12 or 14 ft. above the floor, and it is seldom carried above this height. As the ore is broken by the miners, and falls under foot, it is shovelled into passes leading into chutes in the level. When large rocks are met with they are broken to a convenient size — about 12-in. cubes — by hammers, or when of extra size, l)y small charges of explosives. In mines where the average value of the ore is comparatively high, or where specially rich shoots occur in the lode, care is taken to prevent loss. To effect this, the tilling is covered with discarded filter-cloths or bags, over which jdanks are laid. Upon these the ore falls as it is broken. If rock has been used for filling, it is usually covered with sand, to give the planks a good bedding, and to prevent them from being splintered and broken by the falling ore. Even if they are broken, no loss of ore results, as it can all be recovered by taking a few inches of sand with it. Not only does this method prevent a mixing of ore and waste rock, but it also facilitates the shovelling. Where the average grade of ore is not high, planks and other covering may occasionally be dispensed with, if it is considered cheaper to shovel off a few inches of sand with the ore, than to lay down timber. The sand is usually in rather a damp condition when sent below, and it packs firmly and forms a fairly solid floor. The ore-passes connect with the level below at distances varying slightly in different mines, and ranging from 20 to 50 ft. apart. This would mean that the greatest distance through which the ore has to be shovelled in the stope would l)e from 10 to 25 ft. In the widest stopes the distances would be greater, but special means are then adopted. In the smaller stopes barrows are used, and in the wider ones temporary tracks are laid for the use of trucks. This method is illustrated by Fig. 60.

As soon as a stope has been cut away to the desired height, preparations are made for filling. The broken ore is cleaned up and shovelled down the passes and the filling — consisting of waste rock, or sand, or both — is poured into the stope through winzes opening from the level above. Rock is obtained from any shaft-sinking, cross-cutting or other development work that may be proceeding. Instead of being hoisted to the surface, the rock is raised to the level above the stope and there tipped. The sand consists of residues or tailings from the ore after treatment in the reduction works. It is sent from the surface, through winzes connecting one with the other, to the desired level; with this material the filling of a stope can be quickly and cheaply accomplished. In some instances the sand filling is distributed to the various passes

Stopes And Stoping

nnder2:roiind by means of electrically-driven belt-conveyors. At the surface the sand is conveyed to the various passes by means of belt-conveyors, or trucks moved by hand or drawn by horse or locomotive traction.

Prior to sending- down the filling, the necessary passes are constructed. These are built of sets of logs or sawn timber, placed in rectangular form and of the same dimensions as the openings to the chutes into the level. At the points where the logs intersect, notches are cut to form a shoulder and to prevent the sets from being forced inwards by the pressure of the filling. The spaces between the sets are closed with waste lumber, so as to prevent sand from falling through. The logs are from 6 to 8 in.

Fig'. 60. Showing' TrucK and Temporary TracKs into Slope.

in diameter at the small end, or if sawn timber is used the dimensions are usually 8 by 3 in. The passes are built up until they are within two or three feet of the back of the stope, and as they advance, the filling is also brought up until it is about level with the top. The stope, or the portion of it that has been filled, is then ready for ore- breaking to lie resumed. AVhen not in use, or when firing is aliout to take place, the to]) of the pass is covered with poles or planks, as a protection for the men and a ])revention against an)’ large mass of ore falling into and blocking the pass. Most of the passes are divided into two compartments, one being reserved for a ladder-way

West Austraijan Mining Practice

to give access to the stope, and to enable the passes to he relieved in the event of their becoming obstructed by ore. The constrnction of a pass is in all respects similar to that shown in Fig. 53. There is, naturally, very great wear and tear on the pass-logs, owing to the hard nature of the ore that is constantly passing through them, and consequently the repair and renewal of portions of the pass — especially the lower parts — is a heavy item of expenditure. Where the logging has been too mncli damaged to he of subsequent use, it remains in place after the stope has been depleted and abandoned.

In slopes of any great length, several winzes will open into them, and it is the practice to commence filling from these winzes, and keep advancing with the miners who are breaking ore. In this way the filled portion is ready for the resump tion of ore-breaking as soon as, or prior to, the completion of the stope ahead. In mines Avhere the lode inclines flatly, there is more difficulty in filling the stopes either with sand or rock, and in some instances wooden chutes have to be used in order to get the filling to run at all quickly; moreover, in the case of flat stopes, the filling has to be shovelled and packed tightly against the hanging-wall.

The flat-back system of stoping described in the foregoing paragraphs may be briefly summarised. The lode has been cut away along the whole length for the full width of the block of ore operated upon and to a height of from 10 to 14 ft.; the broken ore having been removed through the passes and chutes, the excavation is artificially filled up with sand or rock, through which passes, or openings, have been left for communication with the level below. The subsequent work is a repetition of what has been described, until the upper level is reached, and the block of ore has been completely removed. The methods by which the timbering of the upper level is nicked np and secured, when the stope breaks through, have been described in that section of the chapter dealing with “Timbering of Levels.” The ends of a stope are usually left open. The length of a stope may be taken to represent the extent of ore of profitable value; the lode may, however, continue at each end, though of too low a grade to render its immediate extraction profitable. A time may come when, owing to altered conditions of mining, or improved methods of treatment and handling, this ore of low grade may be profitably dealt with. If the stope were filled hard up to the solid ends, it would be very difficult to break out the adjacent ore; in all probability, the old filling, on being disturbed, would commence to run, and stop the work. In order to guard against this difficulty, the stope ends are left open by carrying up a rearing of timber, or a stone walling, at a distance of several feet from the solid end. The rearing is constructed by fixing stalls horizon tally across from wall to wall of the lode and about 5 feet apart. These are lagged inside with poles temporarily held in place until secured by the filling thrown against them. In ore-bodies of considerable width, it is not possible to obtain timber of the necessary length for stalls, and a stone wall or “stilling” is built. The stone is obtained either from the rock sent down for filling, or by breaking out the adjacent walls of the stope. This method is rather more costly than timbering, and it is not every man that succeeds in building a good dry stone wall. The stone rearings, how ever, are not often required, as the more usual practice is to construct bulkheads of

Stores And Stoping

timber. The open spaces thus formed at each end of a stope are useful in several ways; they permit of the solid lode being mined at some future time ; they greatly assist the ventilation of the mine ; and they form a convenient means of access to the stope. The machines and steel are hoisted by means of windlass, block and tackle, or mechanical air-hoists, and ladders are fixed for the use of the men.

Timbering . — Owing to the strong character of the lodes and enclosing rock, very little timber is required in the stopes, and most of that used is recovered. Where the walls are not strong and are inclined to flake off after exposure to the air, pro]is and head-boards are used, but at the time of filling, these flakes can be brought down and allowed to lie in the stope. In wide stopes it is sometimes found necessary to support the ore at points where it threatens to come away in large masses — probably breaking away from a false back, or a line of bedding. The sup port given usually takes tlie form of “pig-stys.” These are constructed of round logs, built up in the form of a hollow square, and forming a support of great strength. They are built upon the filling, and if extreme pressure is to be expected, a decking of planks is first laid, so as to give a greater bearing at the base. The logs are notched at their points of intersection, so as to give them some hold against any lateral pressure. The pig-stys are built up to the back, and planks, poles, and wedges are packed and driven in between the logs and the ore, to prevent any downward movement or loosening of the back. The pig-stys are placed at such distances apart as occasion may require, and their use and construction are shown in Fig. 61. As the stope advances, the timbering is removed, and may be used again. Tliis method of timbering the stopes is not followed where the hanging- wall is very weak; in such cases bulkheads are built from wall to wall, perpen dicularly, and are left as permanent supports. The best form of support is that obtained by pillars of solid rock. These may be represented by intrusions, or “horses” of country rock, or by masses of very low-grade ore which may be left standing. By the use of ladders and by constant supervision, the state of the backs through all the stopes is ascertained daily. If, when tapped by bar or pick, the sound is “drummy” or hollow, supports are put in place without loss of time, or the weak ground is broken down by bars or small charges of explosive until a sound back has. been exposed. In most mines it is the practice to keep special men employed in examining the stopes.

Ore-breaking is effected chiefly by means of machine-drills and blasting, and the skill of the miner is displayed by his ability so to place the hole that the maximum quantity of ore may be broken with the least expense in drilling and explosive. As far as possible the holes are slightly depressed so as to permit the use of water for boring, thereby minimising the . The explosive is brought direct from the underground magazines in sufficient quantities for the holes about to be charged; any surplus is returned to the magazines, and none is allowed to remain in the stopes.

Compressed air for the machine-drills is brought from the mains by pipes laid up the ladder-ways of the passes, or the rearings at the stope ends. The pipes are

WP]KT AITSTRALIAX MINING PRACTrOE

i4(;

brought to witliiii a foot or two of the top of the pass and tliere furnished with a valve. From tins point two or more branches are led into the stope and laid in any direction required, the connection between their ends and the drill being formed by lengths of flexible rubber-hose. AVhen the sto})e faces are l)ored out and ready to l)e fired, the valve in the ])ass is closed, the brandies and hoses are disconnected, and the jiass is covered over with })lanks or poles if near the ]ioint of firing. Warning is also given to all men working in the stope, or in the levels above and below, so as to avoid accident. Through the rises opening on to the up]Ter level, and by

Fig. 61. — Showing Construction of Pig-stys.

means of the ventilation afforded liy the rearings, the smoke and dust caused by lirim:: are soon dis])elled. and a speedy resumjition of work is rendered possible.

/c Scaffoldiiifj. — In taking out the first cut along the back of a stope, the or(“ ])reviously l)roken may afford the miner sufficient elevation for the next cut. If not, a stage of timber becomes necessary for the men to stand upon. In a narrow stope this can lie constructed by placing bearers across from wall to wall, and covering them with planks, Imt in wider stopes such a course is not possible. A scaffolding is then made with vertical and cross poles, usually fastened with ropes at the points of intersection. The loss of ro]ie by wear and tear and carelessness constitutes an item of ex])ense, and to eliminate this a special scaffolding hook of iron has been designed. (Figures 63 and 64). It is found to be very secure, simple to make and adjust, and less ox]iensive than ro]ie.

S'roPF.S AND SToiMXG

1A7

Costs. — Of the fou]’ mines in which tiie flat-hack stope is adopted, three carry on the work under contract, and one on wages only. Under contract the miners are paid according to the quantity of ore they break out. and as a rule tlieir average daily

Fig. 62. Stage Scaffolding in Stope.

earnings are in excess of the minimum wage lirevailing in the district for that class of mining. In the mine where the work is done hy day lalionr, only the ordinary rate for day work is ])aid. and the cost per ton is 6s. 7d., as com])ared with 7s. lOd. and 9s. 9.9d. ]ier ton of tlie work jierformed hy contract. But in the two mines where the

West Australian Mining Practice

contract system is in force the ore is very harder, and the machine-drills used range from 21/2 to 34 inches, while the stopes are not of exceptional width. In the other mine a softer ore enables 2-inch macliines to he used and operated by one man, whereas two men are required to operate the larger machine.

Payment for contract work, in the two instances under notice, is made according to the nnmher of cubic fathoms (216 cubic feet) broken, and on the hole-footage system. The former is represented by the ground excavated, and the latter by the aggregate depth of holes bored in the face of a stoje. Where the cubic fathom system is adopted, the lode is easily distinguished from the country rock, and it would not be possible for the contractors to increase their footage by In-eaking into conntry.

They are required to keep the ore as free as possible from waste rock, and carelessness or indifference in this respect wonld render them lialile to a penalty or to dismissal. In the hole-footage system, there is necessarily an increase of supervision required on the part of foremen and shift-bosses. The contractors have to be instructed as to the direction holes are to take, and the widtli of face that can he worked. The holes also have to be measured np before each firing. It devolves upon the officers to see that no unnecessary holes are bored, and that no holes are bored in positions where their etfectiveness is limited; for holes such as these no payment would he made.

The measuring is done by means of steel rods. In these rods holes are bored 12 inches apart, for the purpose of measurements. The management provides rock- drills, power, and steel, and the contractors supply labour, light, and explosives.

Stopes And Stoping

In the mine stoping on wages, the supervision necessary is almost as close as that exercised in the mine that follows the hole-footage system. This is mostly due to the erratic nature of the shoots of ore, and no system of contract work could here be adopted with advantage. Close supervision is required, amongst other things, in order to follow the assay results, and to guard against the breaking down of masses of valueless ore, which frequently has the appearance of being better than the pay-ore.

More work is done per day under contract than would be the case on wages only ; and the earnings of the contractors work out at about 15s. to 15s. 6d. per day of eight hours, as against the minimum legal wage for this class of work of 13s. 4d. per day. Prior to the introduction of contract work in one mine, it was found

Wkht A Ustr A L I A N M I N 1 Ng P R Acaptce

that the average qiiantity of ore broken per man per day was 4 tons, whereas under contract it was snl)sequently increased to 7.31 tons per man, a result that was of benefit not only to the mine-owner, but also to the miner, since it represented in his case a higher rate of wage.

In regard to tlie segregation of costs the following example is given by the Golden Horse-Shoe, showing the cost of breaking, trucking, and hoisting 19,596 tons of ore: —

Particulars.

Wages.

Stores.

Total.

Cost

per Ton.

£

s.

d.

£

s.

d.

£

s.

d.

s.

d.

Superintendence

Miners, Stoping

4,366

4,366

,, Gangways and Repairs...

Trucking

Filling Stopes

1,047

1,068

Brace and Platmen

2T9

Hoisting Expenses

Timbering

)

7 '92

Tool-sharpening and Rock-drills, etc.

6'60

Assaying and Sampling

Explosives

6'48

Compressed Air

(leneral Mining Expenses

Pumping Expenses

Candles

K)5

Total

7,514

2,112

9,626

Rill Stopes. — As in the other methods of overhand stoping, the rill stope is commenced from the bottom of a rise, and is carried outward and upward; but instead of the back being carried forward on lines parallel with the level, it is inclined at a convenient angle. The first cut slices off the corner formed by the intersection of the rise and the leading stope, leaving the back of solid ore standing at an angle of say 45deg. Each subsequent cut is commenced a few feet higher up the rise, and extends further along the leading stope. Similar operations may be commenced from a second rise at tlie further extremity of the block of ore in process of extraction, or from an intermediate point — the two stopes gradually approaching one another, and eventually meeting about midway between the rises. In this event, the standing ore would be triangular in shape. The broken ore would slope downwards from the two ends of the stope towards the centre, and would be constantly gravitating to the chute in the level, as the ore was drawn away (see Fig. 58). By the adoption of this method, the labour of shovelling is reduced to a minimum; some shovelling

S'l'Ol’ES AND SroPlXG

is necessary, but far less than in flat-back stopes. In the early stages of stoping, the ore is drawn out through the level-timbering, at points which are kept moving- forward in unison with the advancing foot of the rill. The chutes, through which the ore runs to the trucks, are frames so constructed as to be easily movable along the level from point to point, and they are thus moved until the point is reached at which it has been determined to rear up a permanent ore-pass and ladder-road. The distances apart of these passes vary from 30 to 50 feet in different mines and their construction is, in all respects, similar to those used in the flat-back stope. When the stope has been carried up to its maximum height — a matter determined to some extent l)y the nature of the ore — the broken rock is cleaned up and drawn off through the chutes, and sand or waste rock is fllled in through the winzes from the upper level. The filling is brought up close to the back, and in the case of sand it packs into a good firm floor. Unless the ore is of very high grade, no planks are laid down for it to fall upon, and it is found that by subsequenth" removing a few inches of sand when cleaning up the stope all the ore is removed. xV stope is commonly raised to a height of 14 feet; the stope is then cleaned out, and all broken ore run through the pass; the latter is then built up and the filling run in.

In the method of working a rill stope, there are one or two points of difference to note in comparison with that of the flat-back system. It has been shown that a considerable economy in labour is effected in the handling of the ore broken, the ore having, in a great measure, merely to be assisted in its gravitation towards the ore- pass. In filling the stopes, very little actual handling of the material is necessary, as it naturally gravitates down each side of the slope formed under the rise or winze by the filling previously run into the stope.

Timbering. — In the flat-back stope, the ore is being cut away in layers, which approximate more or less to the natural bedding planes of the ore-body; it is there fore possible that large horizontal masses are left hanging, which may fall by reason of their own weight. In the rill stope this is not so much the case, because the inclination at which the stope is carried crosses the lines of bedding at an acute angle; con sequently, no extensive layers are completely exposed along their entire length, and a portion remains locked in the standing mass. The weakest spot would probably be found at the point of the triangle formed by the junction of two synclinal stopes. Supports to the back and walls are also of the same type as those in the flat-back stope, and pillars are left wherever possible. In the rill system it is probable that supports to the back are not so frequently required. For reasons already quoted, there would appear to be less risk of a large mass of ground being weakened. The methods of breaking out the ore, of building passes, supplying compressed air, rear- ings, and providing access for men and tools, etc., are identical with those described under flat-back stoping.

Costs. — Of the four mines in which the rill stope is chiefly adopted, one only is worked entirely on contract. A second adopts part contract and part wages, and the remaining two work on wages only. In the contract mine, the lode is well defined, and the ore-bodies occur with a good degree of regularity. Ore-breaking can, there fore, be carried straight ahead for the most part. In the wages mines, contract work has been tried and found to be unsatisfactory. This is due partly to the erratic occurrence of the shoots of ore and in some measure to the weak walls. Under

West Australian Mining Practice

conditions such as these, contractors would meet with frequent delays and drawbacks, and with these disabilities in mind, would quote prices which, while insuring them against possible loss, would bring the cost of breaking beyond what it could be done for on wages. It has previously been pointed out how, in mines of this type, it is common to discover ore-bodies lying isolated and apart from the main body, in one or other of the walls. To deal effectively with these on contract would be a difficult matter. The occurrence of large bodies of low-grade ore, not required to be broken down, also renders the wages system the better of the two, as progress can be suspended at any moment and labour diverted elsewhere, pending sampling and examination.

Where contract is in force, payment is made on the cubic fathom of 216 cubic feet. It is estimated that the ore is broken for 6s. per ton less than it costs under wages. Here, also, it is found that individual earnings exceed the ordinary rate of wage, and that parties of skilled miners can average 17s. per eight-hours’ day per man.

The following shows one example of the method of splitting up costs: —

s. d.

Ore-breaking . . . . . . . . . . . . . . . . . . . . . . 4 0.340

Timbering, stope-filling, and maintenance . . . . . . . . . . . . 1 5.698

Hauling and transit . . . . . . . . . . . . . . . . . . . . 1 10.561

General charges . . . . . . . . . . . . . . . . . . . . 0 4.293

Cost per ton

Shrinkage Stopes. — The shrinkage method of stoping differs from the preceding- methods, inasmuch as only a proportion of the ore is removed as it is broken, and no lining is required until the lode has been broken down between two levels, and all the ore removed. In the actual breaking of ore etc., the practice is similar to that of the hat-back stope. Stopes are commenced on the lower of two levels, and from a rise, as in the rill and hat-back systems.

If the ore has proved to be of a prohtable grade immediately above the back of tlie level, a leading stope will have to he taken out, and the level timbered; but if the Imck is in low-grade material, and the zone of pay-ore is some feet above, a commence ment will be made off a rise at that level. A stope or intennediate drive will be put in and the mass of lode between this and the level will be left standing intact. Reference has already been made to this practice. (See Pig. 59).

As the ore is broken down it is allowed to lie on the hoor of the stope, and only a portion is drawn away, to allow sufficient room for the miners to continue working on the back. This portion ranges from 30 to 40 per cent. This process continu-es from start to hnish of the block of ground operated upon. When the lode has been broken out from level to level, the intervening space contains the ore from the lode, less the proportion drawn away from time to time for convenience. The breaking having been completed, the stope can be drawn upon as frequently and con tinuously as may be desired, and until its contents have been exhausted. When the stope has been completely emptied, the tilling with sand or other material is undertaken; though if the walls are strong, or no danger to the mine is to be feared, the expense of filling may be avoided altogether. This last practice, how-

Stopes And Stoping 153

ever, is not commonly adopted. The empty stope is a convenient place for dumping- waste rock obtained from development work, or the residues from the reduction works in instances where the surface area is limited, and the sand heap rapidly accumulating.

The ore is drawn off through chutes placed along the level at distances ranging from 12 to 25 ft. apart in different mines, or hy means of a “ Chinaman ” chute, as illustrated in Fig. 55. No timbered ore-passes are required as in flat-hack and rill slopes, because there is no tilling to be held back, and the ore runs to the chute, when opened, until the stope is empty. But in slopes of considerable length, passes

Fig'. 65. Face of Stope bored for Firing'.

for the purpose of giving access, and ventilation, to the stope are built, but at greater intervals than in the other kinds of stopes. Access is also gained through the rearings, and down the winzes from the upper level. Machines and tools are either lowered or hoisted through these ways, whichever may be the shortest road into the workings. No timbering is required to support the stope, but, whenever possible, pillars of country rock or of low-grade ore are left standing to support the walls.

Where the ordinary form of chute is used care is taken to break the larger lumps of rock into about 12-inch cubes while they are in the stope. This matter requires to be attended to, otherwise it is probable that in time the chute will become blocked with over-size pieces. In that case blasting with small charges of explo sive has to l)e resorted to, as from the position of the chutes there is no possibility of using hammers. It is for this reason that chutes fitted with stopper-boards are

WEST AESTKAJ.LAN AiiNINE PRACTICE

It)!

preferred, as being less expensive than iron doors and levers. Despite the care exercised by those in charge, there is certain to be a large number of over-size nieces of ore left under foot in each stope — more particularly if the work is being carried on under contract — and the quantity is of more consideration to the con tractor than is the size to which the ore may have been broken. 'Where the “China man” chute is adopted, those over-size pieces are more easily dealt with. They fall through on to the floor of the chute, where there is ample room to break them up, either by hammer or explosive, and with little fear of doing damage to anything.

Costs. — The cost of breaking ore, with its attendant charges, trucking, hauling, etc., under the shrinkage system is shown to vary from 5s. 9.89d. in the Kalgoorlie group of mines to 8s. ll.Ild. in those that are further afield, where wages and freights are considerably higher.

Comparative Statement of Costs.

For the period, 1st January to 30th June, 1908.

Items.

Sons of Gwalia, Ltd.

No. 10.

Great Fingall Consolidated. Ltd. No. 11.

Lake View Consols, Ltd. No. 9.

South Kalgurli Gold Mines, Ltd. No. 6.

Oroya Brownhill Company, Ltd. No. 3.

Breaking Ore— Tonnage ...

70,543

126,917

58,599

52,392

67,290

s.

d.

s.

d.

s.

d.

s.

d.

s.

d.

Labour ...

L.xfilosive.s

6'24

6'99

6'75

Timber ...

2'21

Candles...

0'75

Steel

Sundry Stores

Power ...

3'49

6'33

4'56

Assaying and Sampling

F79

Repairs and Maintenance ...

3'85

Pumping

O'Sl

2'12

Total Cost per Ton

S.

d.

S

d.

s.

d.

S.

d.

s.

d.

Filling Slopes — Total Cost per

Ton

0'55

Trucking and Raising Ore —

s.

d.

S.

d.

s.

d.

S.

d.

S.

d.

Labour...

lit

Timber ...

—

—

—

Candles, Steel and Sundries

F53

Power ...

Repairs ...

Pumping

—

Total Cost per Ton

Grand Total Cost per Ton

ST()Pi]S AND STUFNG

A summary, showing the mines adopting the different methods of stoping, the width of ore-hodies mined on contract or wages, the cost per ton of 2,000 lb., and the approximate tonnage treated per month, is given below: —

West Australian Mining Practice

Relative Advantages And Disadvantages Op The Several Methods

Op Stoping.

Flat-back Slopes.

Advantages. — When either the lode or the country rock is of such a nature tiiat it will not stand well but is liable to fall, it is very much easier to secure either the back of the stope or in the case of underlay lodes the hanging-wall, by means of timber, and a good deal of this timber can be recovered when the stope is being lilled, thus minimisiiig an item of heavy expenditure to those mines situate in sparsely-timbered districts far removed from a railway line. Prospecting work can be done from the stope by means of crosscuts, etc., if, as is sometimes the case, small veins of ore are found to be penetrating the country rock from the walls of the lode; such veins may lead to valuable bodies of pay-ore, and the necessary de velopment work can be more conveniently and economically done from a flat-back stope than from a rill or shrinkage stope, as the rock and pay-ore resulting from such prospecting can be separated in the stope and the waste rock left to form por tion of the filling. Another advantage attendant upon this system of stoping is that it is comparatively easy to leave behind low-grade ore, and to sort out the pay-ore, and in some mines where seams of high-grade ore lie in that of too low a grade to pay for treatment, this feature is of great importance.

Disadvantages. — The disadvantage of a flat-back stope is the cost of trans port of the broken ore to the passes. In large slopes truck-roads have to be laid and the ore must be shovelled into the trucks and tipped into the passes. In smaller slopes wheel liarrows are resorted to, and some cases even these cannot be used, but the ore has to be shovelled two or more times before it arrives at the pass, and again when the stope has to be filled, extra shovelling is necessary to distribute the filling as required.

Rill Slopes.

Advantages. — The principal advantage derived from this system of stoping is that the cost of shovelling broken ore and filling is greatly reduced. An other important feature in favour of the system is that should the ore-body be laminated horizontally, or l)e separated by flat floors, or greasy heads — a condition necessitating extreme vigilance in order to prevent falls of ground — the ore can be stoped on the rill system with greater safety and less expenditure for temporary supports to hold the I'ack than would be the case under the flat -back system. The reason for this is that in consequence of the stope being taken at an angle of approxi mately forty-five degrees, the flat layers of ore between the laminations, or floors, are never left unsupported for any appreciable distance in the direction of their lengths, as is the case in a flat-l)ack stope. As an illustration of this, suppose a hole six feet square knocked through a brick wall, the course of liricks immediately above the opening will require support, as there is nothing but the tensile strength of the mortar to hold them in place; but suppose the hole be triangular instead of square, with the apex of the triangle uppermost, then there will be no danger of the top course falling, as each brick projects only slightly beyond the one im mediately below it, and consequently is only unsupported for a short portion of its length. This triangular hole in the brick wall is similar in shape to a rill stope.

Stopes And Stoping

Disadvantages. — Caution must be exercised by the men in getting to and from the faces at which they are at work, as, in climbing up or down, an accident may occur through pieces of broken ore being displaced and falling down the rill. This form of stope is not so convenient as a flat-back if the ore should be varying widely in grade, and it should become necessary, as is often the case, to send ore of a particular value to the mill in order to maintain an average output. To work a rill stope at its best economical efficiency the ore should be broken continuously on a face, as it is costly and inconvenient to break more ore in one portion of the stope than in another. Prospecting work into the walls of the lode cannot be so easily done with this system of stoping as in the flat-back, be cause the work of ore-breaking cannot be suspended in any one portion of the stope and carried on elsewhere on the same rill for any length of time, also the rock from such prospecting work is liable to get mixed with the ore coming down the rill, and as the whole stope advances quickly it is inconvenient to arrange that the s])ot where a crosscut has been put into the wall shall be left so as to be accessil)le. It. a rill stope the work of carrying machine-drills and tools to the faces when boring is to be resumed is arduous; the machines, etc., must necessarily all be removed from the stope when firing, and be hoisted through the winzes to the level above or sent down to the level below, whereas in a flat-back stope they can be left in the stope when firing operations are in progress, so long as they are sufficiently far removed from the face, and are protected by a covering. Where residues are used for filling, care must be exercised, when cleaning down the stope of broken ore before filling, to allow as little as possible of the filling to run down the rill and into the pass with the ore. Although the presence of a small quantity of residue sand or slime in the ore to be milled is not of much consequence in a wet-crushing plant, trouble may arise from this cause where the treatment is dry.

Shrinkage Slopes.

Advantages. — The method of shrinkage stoping has the great advantage that no shovelling whatever is required; after the ore has been broken out all that is necessary is to see that the larger pieces are broken to a size that will not block the chute. There is also no risk of ore being mixed with filling, as the stope cannot be filled until all the ore has been drawn away.

Disadvantages. — The principal disadvantages of a shrinkage stope is that if any country rock should fall from the walls of the lode either while stoping is proceeding or while the stope is being emptied, such rock must necessarily be mixed with the ore, and will consequently go through the mill. The loss thus sustained is not immediately apparent as it is only shown by the lowering of the grade of the ore treated. Other conditions being equal, the effect of this disadvant age varies with the width of the ore to be stoped, as for instance in a stope 100 feet in width where an average of one foot of rock has fallen from the walls, the mill would be treating only one per cent, of valueless material, but in a stope ten feet wide where an average of a foot of country rock had flaked from the walls, ten per cent, of valueless rock will be going throngh all the processes of the treat-, ment plant. No prospecting can be done from a shrinkage stope for the reason that all rock from any such workings can only be disposed of by allowing it to mix

WPlSr AUS'rRALIAN ALIXING PRACTICE

with the broken ore in the stoi)e. The use of this system is not advisable where there is a likelihood of horses of country rock occurring in the lode, or where blocks of ore of too low a grade to pay for treatment are likely to he encountered, as such horses or blocks cannot well be left behind, but must be liroken with the pay-ore.

Summary.

To summarise the advantages and disadvantages of the several methods of stoping, the following observations are worthy of special note.

Ender the best conditions the shrinkage stope is undouldedly the most economical system of mining, it is obvious, however, that only a certain class of mine can adopt it witli unqualified success, that is, a mine in which the walls of the lode are hard and dural)le, not inclined to Hake off, and 1)oth foot and hanging- wall are well defined and underlying at a consistent angle throughout. Moreover, the angle of inclination must be such that the broken ore will run freely on being drawn off, otherwise great difficulty will l)e experienced in removing it from the stope, as it is often inq:ossible for any woi-kman to enter into the excavation after the withdrawal of a large ((uantity of ore. ITnfortunately, the number of mines that conform to these requirements is not great. In the majority of the mines of this State the walls are inclined to break away, and the ore-bodies to form lateral extensions, or bulges, into one wall or the other.

In mines with weak walls the objection to the shrinkage method of stoping would be that, as the broken ore is drawn away, masses of rock of various sizes would also flake off the walls and become mixed with the ore. Thus the value would be materially decreased, and in cases where the margin lietween i)rofitable and nnprolitable ore was narrow, the intruding rock might make just the difference between profit and loss.

In flat-back and rill sto[ies, the weak si)ots in the walls can be detected, and may be temporarily secured with timber until such time as the stope is ready to be filled; the waste rock can then be allowed to fall in and become part of the necessary filling, or, even if waste falls with the ore in the course of stoping, there is no difficulty in sorting out and throwing it to one side, and thus jireventing it from going down the ore j'tasses. But this is not possible with shrinkage stopes, since whatever falls into the stope remains there, until it passes out with the ore hrough the chute. Judging by the nature of the country rock existing in the majority of the mines of Western Australia, it is })robable that the quantity of waste rock produced by the flaking of the walls is not less than from ten to fifteen ]ier cent, of the ore contents of the lode, and in some mines wonld probably amount to thirty or forty per cent. In mines where the walls might be estimated to yield these quantities of valueless material, the shrinkage system of stoping could not be adopted with advantage, even though it were shown to be a cheaper method than either of the other two systems. Nor could the system be advan tageously emplomd in those mines in which, as has been pointed out, large masses of the ore bulge out into the walls. These outlying masses would

yield but a small portion of their contents under the shrinkage system; the greater proportion would necessarily remain lying on the edge formed by the removal of the bulge. Difficulties would also arise in mines where large masses of low-grade ore are found in conjunction with the higher-grade

Stopes And Stoping

shoots. To some extent it might be possil)le to leave these standing intact, but it is certain that as the ore was drawn away from the stope, these low-grade bodies would contribute large quantities from their exposed sides. It depends, therefore, upon the character of the walls whether the shrinkage system of stoping is the one best adapted to the requirements. Tmder the best conditions, it appeals to the mine-owner as being the least expensive method of breaking out the ore; but unless such conditions exist, its adoption may prove to he anything but satisfac tory. Happily, the nature of the walls of any mine is easily ascertainable, and will determine the method of stoping best suited to the jrevailing conditions.

West Austrvlian Mining Practice

Chapter Ix

Underground Transport Of Ore

Truck Roads — Trucks — Ore Transportation — Plat Ore-Bins.

Truck roads. — The transport of ore or rock, from any point on the levels of a mine to the shaft, is performed with trucks propelled by men; only in one or two instances is horse traction employed. The adoption of electric or pneumatic power is, however, under consideration in some mines. In the course of development by cross-cutting and driving, rails are laid for the trucks required to remove the broken rock or ore. These trucks subsequently form the ways along which the whole traffic of the mine is conducted, and care is taken to lay them in a way that will facilitate the work of trucking. With heavy loads to handle, a badly laid track becomes a source of trouble and delay, owing to frequent derailment and overturning of trucks. The care given to this matter in the first instance is repaid by the smoothness and celerity of the transport service. The tracks are graded with a slight incline towards the shaft in order to lessen the labour of moving the loaded trucks. As in the majority of the mines no great quantity of water has to l)e drained away, the incline can be maintained at about one per cent. This gives sufficient advantage to the loaded truck, and does not seriously affect the labour of pushing the return empties. The bed of the track is laid with wooden sleepers, at about three feet apart, on which flanged steel rails are fastened with dog spikes, and the track is ballasted with small rock rammed under the sleepers and rails; the footway between the rails is made smooth for the convenience of the truckers. In drives 7 feet wide single tracks are used, and where double tracks are required the drive is widened to 8 or 10 feet. The rail ends are connected with fish-plates bolted through the rails, and under these junctions a sleeper is placed so as to avoid any inclination of the joint to sag. The gauge of the tracks used in the different mines varies considerably, also the weight of rails — though this is more uniform — generally 141b. to the yard. In the eleven mines re ferred to, four adopt 20-inch gauge, three 18-inch, and the remaining four range from 16 to 18% inches. At points where drives and crosscuts intersect, steel flat-sheets are laid on a timber bed to form a species of turntable. The rail ends connecting with this are cut away on the under side for eight or ten inches, and the upper side is thinned out and tapered with an outward curve. The ends lie flat on the sheets and enable the truck wheels to engage with the rails without difficulty. '

Trucks. — The trucks in use vary in capacity from 1,000 to 1,8001b. of ore. The greater number are end-tipping, with a door hinged on the upper side and fastened below by means of a lever and clutch worked from the rear. A convenient

Underground Transport Of Ore

style of truck is one in which the body is pivoted in the centre, so as to allow an all-round discharge. Each truck is furnished with a door at the end. On all end-tipping trucks the wheels are placed rather towards the rear of the body, so as to allow for tipping. Diagrams of all-round tipping trucks are given in Figs. 66, 67, 68, and 69. In some instances box trucks are in use; these have no door, and are emptied by being run into a frame — known as a “tippler” — and inverted. These trucks possess an advantage in having hut few wearing parts to get out of order, thus reducing repairs to a minimum. In some trucks the wheels are fastened to the axles, which run in self-lubricating hearings, otherwise the trucks generally in use vary only in small details.

Fig'. 66. All-round Tipping' TrucK.

Ore Transportation. — In the case of development work, the trucks are lilled by shovelling, the ore or rock lieing on the floor of the level. From the stopes they are lilled by means of chutes connected with passes — a description of which has been given. In the case of waste rock from development work, the trucks are run direct into cages and hoisted to the surface, or to any level in the mine where filling for stopes is required. In handling ore for the mill two methods are employed; one of sending the ore direct to surface per truck and cage; the other by the dis charge of the trucks into ore-bins constructed below the floor of the plats on certain levels. From the bins the ore is loaded direct into skips. The use of skips in con-

KiL'

WKST AI KI’RALIAN MlNlNlJ PRAX'TICE

- Und Elevation

Fig". 6 7. All-round Tipping' TrucK.

Fig'. 68. All-round Tipping' TrucK.

Door

Fig'. 69. All-round Tipping' TrucK.

.r-

r

t..

X;

Q)

S

C.' - - -' aCx.

. . Y

o

p

l/J

o

o

, *Q0

Od

X: , ® 'os

ro

Jq

Diagram of Underlay Shaft, showing sKips used in bailing and sinKing. Construction of Plat, Ore-bin, etc.

- .Tion -

- .-stl Ti-vint

Undpjrground Transport Of Ore

junction witli plat ore-bins is tiie more recent practice, and is lieing introduced into mines where trucks and cages ha'e hitherto been solely used. In the truck and cage system, the trucks, when loaded, are assembled on the ])lat of an_y level from wliich hoisting is to be undertaken. The platman places the trucks in the cage, over which he has sole control.

Under this system it beconurs necessary to move the cage from one level to another as the rake of trucks at any one point becomes exhausted. This requires the driver of the winding-engine frequently to lengthen or shorten the rope to suit the various levels, and some loss of time is unavoidable. In many instances alternate levels are arranged for loading, the ore from the level above Iming run down to the loading level through a succession of passes. With ore-bins cut at the various levels, and the employment of self-dumping skips of large capacity, hoisting is per formed nmcli more expeditiously; the trucking underground is also facilitated, since, with bins for storage, the time otherwise lost in waiting for platmen and cages is saved. In some mines bins are placed at certain levels only, the ore being sent from the intervening levels through passes.

Plat Ore-bins. — Plat ore-bins are constructed entirely in the solid rock, or with three sides in rock and the fourth formed of timber close to the side of the shaft. The former is the usual method adoihed. In constructing a bin a chamber is cut in the side of the shaft at a depth of al)out 30ft. below the plat. The chamber has a length equal to that of the shaft, and is from 6 to 10ft. wide. From the back of the chamber an incline rise is put up which opens at a ]Doint slightly to one side of the plat. The bin is made of dimensions as may be deemed necessary, but is not less than 50 tons capacity. The chamber is timbered separately from the shaft. Between the front of the bin and the side of the shaft sufficient room is ]n'Ovided for the men engaged in loading skips. The shaft lining is cut away to provide open ings for the ore-chutes. The bin has two doors placed opposite the centres of the two hoisting compartments, the doors being opened and closed by means of rack and pinion. Below the doors iron chutes are hinged, which can he raised and lowered by means of a pulley and counterweight. The skip to be filled is lowered so that the lip of the chute can project a few inches over the mouth of the skip. When the skip is filled the skipman signals for it to be hoisted, and the chute is dravTi up out of the way. Where the bin opens into the plat an iron grid, or grating, is in some instances fixed in the month. The grid is usually made to pass 12-inch cubes, and the oversize pieces have to be broken with hammers. In incline shafts the construction of the bin is similar to that in vertical shafts, but the excavation is made at the back of the shaft. Where it can be arranged, the chutes are designed to jioint down the shaft to guide the ore directly into the skip. With this arrangement there is less liability to spill than when the chute is at right angles to the skip (see Plate XII).

1(54

West Aus4Tevlian Mining Practice

Chapter X

C'Ages, Skips, And S.Wety Appliances .

Cages — IJinged Shoes — Side Safety Cutclies — Safety Hooks — Chains and Bearers — Skips — Gate for changing

Cages — Cage Indicators.

CAGES and skips are used for the puriiose of moving men, tools, tiniher, etc., to and from any level in the mine, and for hoisting ore. Eor handling men at change of shift cages are chiefly used; they are also employed for hoisting ore in mines where skips are not in use.

Cages. — These vary in details of construction, hnt are l)nilt on the one general ])lan. They consist of a strong steel frame, well riveted and braced to gether, the dimensions being determined by the size of the hoisting compartment. Steel shoes fixed to the centre rib of the cage-frame engage with three sides of the guides and prevent the cage from swinging against the sides of the shaft. The floor of the cage is fitted with rails on which the truck stands. The truck is held in posi tion in the cage by means of an iron rod furnished at the end with right-angle arms; the arms are turned nj) to admit the truck, and on being tlirown down they hold the truck securely. The top of the cage is hooded with iron doors to afford protection to the men. The doors are hinged to the frame of the cage and can be raised to allow long lengths of timber and other material to he loaded. Every cage used in raising men in a shaft has to he fitted with safety-catches and appliances to prevent its sudden fall in the event of the rope breaking or becoming detached. A safety detaching hook has also to be famished, so that in the event of the over-wind ing of the cage the rojie will he released and the cage held near the top of the head frame. The rule under the Mines Rerjulation Act is strict in these particulars, and for the protection of the men, the managers are particnlai-ly careful to kee]! all aji- pliances in good working order. All the safety appliances are tested at least every two weeks, and the resnlts recorded in a book kept for that purpose.

Hinged Shoes for Cages. — This ty])e of shoe Avas designed for use in the Main Shaft of the Lake Tew Consols Aline, Avhere skips are ordinarily employed for hauling both men and ore. Occasionally, however, it is necessary to use a cage, as, for instance, in raising waste rock in trucks and shifting- trucks from level to level or to the surface for rejiairs. In such cases the cage is suspended beneath the skip and with the hinged shoe, illustrated in Fig. 70, the cage can be swung into or out of the shaft in a few minutes, without any necessity foi- removing and replacing a skid in the sliaft. The hinged ])ortion of the shoe is folded back, as shoivn in the top por-

Oagrs, Skips Ant) Saff/Pv Appliances

1 (A

Fig'. 71.- Gig' used for repairing' Fig'. 7 2. -Safety Grippers

and timbering' shaft. with lugs.

WEST AUSTRAllAN MINING PRACTICE

tion of tlie sketch, until tlie cage is iu jjosition; it is then closed and the bar raised, as shown in the lower portion of the sketch, the bar being firmly secured in i)osition by means of a split pin. This cage is used solely for conveyance of material, all men l)eing strictly forbidden to ride in it.

Fig. 71 illustrates a gig used for shaft work at the Lake View Consols Mine. ''Lie gig was designed for ius|)ecting and repairing timbers in a shaft with a view to affording the timl)ermen an overhead protection while carrying out this work. Previous })ractice was for the timbermen to ride on the top of the ski]), where they were of necessity exposed to the danger of anything falling down the shaft. The construction of the gig is shown in the sketch. It is titted with a hinged shoe, of a dif ferent design from that descri1)ed above, Avhich allows the gig to be placed in the shaft without removing a skid. It is open on all sides and there is thus ample room for all inspection and repair work. In the ordinary way the gig is hung l)eneath the skip, or it may be attached direct to the winding roi)e. For the work in which it is used the gig of course travels only very slowly through the shaft, so that there is no danger of breaking the bolts that hold the shoe in position.

Side Safety Catches are of different ])atterns, but act on the principle of a spring, being released when the rope parts, and causing gri])pers to clutch the guides and hold the cage. The ro])e is attached to a draw-bar passing down through the

top of the cage and connected with the si)ring and rods which actuate the

grippers. The lower end of the bar is encased by a spiral s])ring. The bar

is slotted at the ])oint at which the frame of the cage is bolted to it,

the slot allowing the vertical movement necessary to control the spring. When the cage is at rest on bearers at the brace of the shaft, or at any level, and its weight is taken off the rope, the spring expands, and the grippers clutch the guides; when the cage is lifted, its weight compresses the spring, and the grippers are forced outward, clear of the guides, and the cage ascends or descends freely. Should the rope break, or 1)ecome detached from the bar, the expansion of the spring immediately causes the gri])])ers to hold to the guides, and the fall of the cage is prevented. The teeth of the gri])])ers are usually chisel-pointed so as to enable them to bite deeply into the wood. The greater the weight of the cage and its load, the deeper will the teeth enter the guides. The different varieties of catches are actuated in this, or in a similar manner, and are found to be satis factory in action. Fig. 72 shows a type of safety grippers fitted with lugs. These grippers are of the usual design with the addition of a special toe or lug to prevent the grippers from cutting through the skids in the event of a loaded skip falling in the shaft. When the gripi)ers come into action the toe of the gripper comes into contact with the shoe on the skid just at the imint where the grippers have their greatest hold on the runners, and their further ])enetration into the skids is pre vented.

At regular intervals — not less than once a month — the whole of the safety gear is taken to pieces examined, cleaned, oiled, and, if necessary, renovated. The result of this examination is recorded. The chief matter to be attended to is the strength and quick response of the s])ring. This is tested by loading the cage with rather more than its usual working load, and sus])ending it over the mouth of the shaft. The shaft is covered with timber on which are laid bags of saw-dust or

Cages, Skips And Sainciv Appliances

Fi3. 73. Details of Double-decK. Cage, showing arrangement of Safety Catches.

West Austra1.Ian Mining Practice

similar material, to prevent the cage falling should the grippers fail to act. The hoisting rope is slackened out for several feet and fastened to the shackle at the top of the cage by means of a rope and slip-hook. The position of the cage is marked on the guides, the hook is slipped, and the cage falls until caught by the grippers. If the springs are in good order, pro bably the fall will not exceed half an inch; but if caught at an inch or inch and half the working condition is considered good. If this is at all exceeded, however, fresh springs are at once fitted, and the cage is retested. Tests are also made direct from the drum of the winding-engine, when by means of special clamps and hooks, the slack is taken up on the rope and the cage hoisted and released, as in the former test. In the latter test the cage has to contend with a certain amount of drag in the length of rope between the cage and the engine, and the grippers are not likely to act quite as quickly as in the former test, unless the springs are exceptionally good. It is con sidered the more severe test ot the two, and is usually practised by the Inspectors of Mines at certain intervals of time. Cages are made in single and double deck styles, carrying one or two trucks, as tlie case may l)e. In some instances the double deck cages are furnished with a double set of safety-catches acting simultaneously.

Safety Detaching Hooks are, by law, also required to be used in conjunction with any cage in which men are raised or lowered. The hook is designed so that in case of over-winding, caused either by carelessness on the part of the engine- driver, or some derangement of the engine, the cage is held in safety at a certain point of the head-frame, and the rope is released and flies clear. If it were not for this device serious accidents to men as well as breakage of plant would ensue in the event of over-winding. The safety-hook is placed between the shackle at the end of the rope and the end of the cage chain. The safety collar, or ring, is securely placed on a frame-work a few feet below the head-frame pulley-wheels. The hook con sists of five or less steel plates, held together by a central bolt tightened up suffi ciently to allow only lateral movement on the jiart of the plates. Of the five plates, the two outer ones and the centre one represent the casing, the remaining plates — one on each side of the centre — are shearing plates, the lower ends of which pro ject on either side at an angle of about 45 degrees. The upper ends of all the plates are slotted so that the shackle of the rope may draw out when necessary. When the hook is placed in position, the adjustment of the plates closes the slot, but leaves a hole through which the shackle-bolt is passed; the plates are held firmly in this posi tion by means of a copper rivet of about W-incli diameter. The bolt of the cage- shackle passes through a hole in the two outside plates and one central plate, leav ing the shearing-plates free to move on the centre l)olt. The fixed collar on the head- frame is placed so that the rope jiasses tlirough its centre. In the event of the cage l)eing over-wound, the upper portion of tlie hook passes through the collar, and the projecting wings of the shearing-plates strike violently against the underside of the collar. The Ifiow causes the plates to be driven in, or closed, as the blades of a pair of shears; the cop])er rivet is thus cut through, and the jjosition of the plates is altered so that their slots coincide and ])ermit the shackle-bolt to pull clear. The forcing together of the shearing-plates causes them to project at their upper ends and just above the upper edge of the collar; these projections hold the cage suspended on the collar.

Fig-. 74. Safety Detaching HooK--first position. Showing hooK engaging with collar.

Fig. 75. -Safety Detaching HooK second position. Showing copper rivet sheared, and shacKle released.

Fig. 76.- -Safety Detaching HooK—third position. Showing projections engaging with collar to suspend cage.

WEST Al\STRAi;iAN MINING PRACTICE

This form of hook has l)een found to fiilhl satisfactori!}" all requirements, and is the one generally adopted. Illustrations of the hook are given in Figs. 74, 75, and 76, and clearly show its construction and manner of working in the thimble or collar.

Cage Chairs and Bearers. — In shafts where cages are used for hoisting trucks of ore, it is necessary that at each level at which loading is to be done the cage shall be brought to rest with its floor exactly level with the flat- sheets of the plat; and that, while it is there, it shall be firmly supported, so that the load of the enter ing truck shall not depress it below the level of the plat. The nice adjustment of cage and plat, and the stability of the cage, are important factors in the work of quickly despatching the loads to surface.

- Side Elevafion —

Fig. 7 7. Improved Chair, attached, to; Cage.

Cage-rests, chairs, or bearers, are of various designs. The most simple form is that of a piece of timber hinged to the set below the flat-sheets and, when in use, thrown over the shaft opening, with its end resting in a hitch on the further side. When not in use, this bearer is thrown back and lies on the floor of the plat; a staple in its free end enables the platman, Iw means of a hook, to pull it up from across the shaft. The use of the single bearer usually results in the cage bottom being bumped up in the centre, on account of the support not being well distributed.

Another form of bearer consists of two bars of 2i/4-in. by %-in. flat iron held parallel to each other by cross bars of round iron, riveted through the lower

Cagk.S, Skips And Safety Appliances

half of file flat bars. The width is adjusted to briii,i>- the bars six inches witliin

tlie outer edges of the cage, so that its weight is distrituited. The ends of the

bearers rest in slots cut on either side of the shaft, and are not hinged to the plat. The bars are placed on edge, so as to afford greater strength. The bearers are

placed in })osition across the shaft, or removed, by means of an iron hook in the

hands of the platman, and they are easily handled ; when not in use they are placed out of the way against the side of the plat.

A tliird method of sup])orting the cage is by chairs worked by lever. These are iron plates or bars, hinged to the shaft-timbers below the plat, and adjusted so that the upper edge permits the cage to rest level with the floor of the plat. The chairs on either side of the shaft are connected by bars at the ends of the compart ments, and are thrown in or out of position liy means of a lever. As rests, they are

Fi. 78. ImprovedBChair, attached to Cage.

as efficient as the bearers previously descriiied, but they have the disadvantage of possibly falling into place in the shaft if care has not been taken to secure the lever. Should this occur at a level that is supposed to be open, a descending cage may dash upon the chairs with great force and cause injury in many ways.

The two first-mentioned cage-rests cannot possibly fall into iflace automa tically; but it is possible for a careless platman to forget to remove them when he may have occasion to move the cage to a higher level. In subsequently arranging

1T:J

West Australian Min Eng Praotice

to pass to a level below that at which the forgotten bearers have been left, the result is disastrous, as cage, bearers and man are more or less injured by the im pact. This form of accident is, however, of rare occurrence. The falling-in of chairs is not so rare and may happen at any time if the appliances are out of adjustment, or the platman fails properly to secure the lever.

A decided improvement in the design and application of cage-rests has recently been introduced. The main principle of this is that the rests are affixed to, and become part of, the cage, and travel with it up and down the shaft. When required for use at any level in the mine, they are capable of being easily pulled into position and form very secure and Srin rests. As soon as the cage is lifted, the rests are released from their horizontal position, and fall back to a vertical position beneath the bottom of the cage. The cage can then travel through the shaft without danger of meeting with obstructions in the form of forgotten bearers or displaced chairs. This appliance also represents an economy in working, as in place of separate sets of rests at each level of a mine, the one appliance does for all. In a large mine working many levels, the saving would be appreciable.

Fig'. 79.“ Improved Chair, attached to Cag'e.

This style of rest can be used for double as well as single-deck cages. In construc tion, the appliance consists of a 24-in. steel rod turned to a diameter of lA-in., attached to the lower side of the bottom of the cage by means of %-in. staple-bolts passing through the head of the rod; this head is 71/2-ih. by 4% -in. by %-in. thick. On the rod a sleeve, having right-angle projections at its base, is fitted to move freely up and down between a collar on the upper end and a keyed nut on the lower end of the rod. At both ends of the cage, at points 2 ft. 2iA in. from centre to centre, two arms, or bearers, 17 by 2 by 1 in., are pivoted on to lugs attached to the bottom of the cage; each pair of bearers is connected by a bar of %-in. diameter. The arms (four in number) are linked to the

Cages, Skips And Saeeia Appi.Iances

projections on the sleeve Ly rods measuring 202 Cy 2 hy % in.; the point of connection betAveen rods and bearers is about nine inches from the ])ivoted end of the bearers. The AAmigbt of tlie sleeve and bearers, etc., causes the sleeve to rest at the loAver extremity of

Fig'. 80. Illustrating Improved Chair attached to Cag'e and showing' braceman drawing out bearers.

the centre rod, and the bearer to bang vertically in the shaft, beloAv the bottom of the cage. This ])osition is antomatically maintained Avbile the cage is in motion, or Avbile sns])ended in the shaft. On arriAml ot the cage at a level Avere it is to be loaded, the platman, liy use of a booked rod, draAvs the nearer pair of bearers toAvards

WEiST AUSTRALIAN MINING PRACTICE

him, causing the slee'e to rise along its centre rod and force outwards the bearers on the far side. Tlie bearers are drawn out horizontally and the cage is lowered and rests on the hearers, which lie in a slot cut in the flat-

Fig'. 81.— Self-tipping Safety SKip,

Elevation and end view.

Cages, Skips And Safety Appliances

Fig. 82. Self-tipping Safety SKip. Half Plan and Half Section at a h.

Fig. 83.— Self-tipping Safety Skip. Half Sections at c d and at e /.

ijt Tapped

haf" V" ’

Fig, 84. -Hinge an I Re '4 on, bottom of SKip.

Details of Self-tipping Safety Skip.

West Australiax Mixing Prac'Tice

Details of Safety-SKip 'continuedi.

sheets of the plat ; when the cage is again lifted, the hearers fall hack into their former vertical jmsition. It will he seen that the mechanism is of the sim})lest description, and it is withont springs to get out of order, or to reiinire rei)lacenient at stated times. With ordinary care to keep the central rod well Inhricated. there is no danger of the hearers retaining a horizontal position after the cage is lifted. In practice, these rests are found to he very satis factory. Figs. 77, 78, 79, and 80 clearly show the details of construction and use.

Skips are designed for hoisting ore in large quantities. They are adapted to both vertical and incline shafts, and to shafts that are partly vertical and partly underlay, or incline. Those in use in the principal mines of this State range in capacity from 1,000 to nearly 7,000 Ih. of ore each, and they are self-emptying. In construction they are steel, rectangular 1)odies, sti'ongly ])ut together, and riding- in a frame, to the upper part of which the hoisting ro])e is attached. The attach ment to the frame is such, that, at the ti})ping floor on the shaft head-frame, guide rails engage with wheels on the ski]) and deflect the l)ody from the vertical; the frame retains its vertical position on the shaft guides and, hy gradually rising, almost completely reverses the ski]i, thus quickly emptying it of its load of ore. On descending, the ski]) falls hack into its place in the frame.

Odie ski])s in use in sluifts that are partly vertical and partly underlay, are furnished with wheels to take the track on the underlay ])ortion. The rails on the incline are continued u]) the curve until they correspond to the vertical side of the shaft, where the wheels are no longer of use; in descending, the wheels engage with the rails without trouble and the skip proceeds down the incline. The frame of the skip travels on guides l)oth in the vertical and incline portions of the shaft.

Both descriptions of ski])s are fitted with safety appliances of design and action similar to those attached to cages. They do not however, require to be fitted with chairs to hold them while being loaded, because in mines where they are used the loading is done from plat ore-l)ins by means of chutes delivering the ore direct into the ski]). For the hoisting of large quantities of ore daily, the nse of skips is considered to be much quicker and more economical than that of cages and trucks.

Cages, Skips And Saeety Appliances

\VEST AU.Sl’RAJ.lAN MINING PRACTICE

CAGFS, SKIPS AND SAIM7rY APPIGANCES

The acconipanying tal)le shows the methods employed in hoisting ore in the i)rincipal mines, and the load that is raised at each ascent of the cage or skip: —

N'o.

of

Mint-

.Average

Name of Mine.

Locality.

Hoistinf.? Appliances.

CapacitNL

monthly

tonnage

hoisted.

lb.

Tons of 2,000 lb.

Great Boulder Proprietary

Kalgoorlie

! Double-deck cages and box trucks

1 Skips, self-dumping...

1,568

6,720

14,000

Great Boulder Perseverance

Single-deck cage and side and end tipping trucks

1,800

17,500

Oroya Brownhill

Single-deck cages and end-tipping trucks

1,000

12,000

Associated ...

Single-deck cages and box trucks

1,568

10,000

Kalgurli

Double-deck cages and end-tipping trucks

1,500

10,500

South Kalgurli

Skip, self-dumping ...

1,000

9,000

Ivanhoe

"

Skip, self-dumping

4,500

19,000

Golden Horse-Shoe

Double and single deck cages

22,800

Lake View Consols

Single cage and skips

1,600

10,500

Sons of Gwalia

Leonora

Skips, self-dumping ...

3,920

13,000

Great Fingall

Cue

Skips, self-dumping ...

4,000

21,500

PRT PLAN HALF SECT' THRo' AB.

Fie'. 91.-Self-tipping SKip for Vertical and Incline Shaft.

Fig'. 92. Self -tipping' SKip in the act of discharg'ing'.

partmeut. The method commonly in use is to make one length of guide, from the collar of the shaft upwards, capable of being removed, or at least drawn to one side. When a cage has to be taken off, it is lowered below the collar of the shaft, the guide is unbolted at the bottom and drawn to one side; the cage is then raised, drawn away from the remaining guide, and hauled on to the brace. An improve ment on this method is represented l)y a swinging gate and, where adopted, it is

WEST AUSTEATJAN iMTNING PRACTICE

Gate for changing cages. — In the ordinary course of work it becomes neces sary to change cages and skips in a shaft, principally for purposes of overhaul and repair. As the shaft-guides and the guide-shoes on the cage, combine to form a species of frame, a way has to be devised to get the cage out of its com-

C!A(JKS, SKIPS AND SAPF/rV APINJANCES

found to act simply and with less trouble than the method just described. The gate is formed of the centre-timbers dividing the two hoisting compartments of the shaft. This is made movable from the collar-set of the shaft to a height of 10 feet, the upper end coming just below one of the dividers in the frame of the sky-

Fig'. 93. Self-tipping' SKip completely discharged.

shaft. The post on the side of the shaft furthest from the winding-engine is chosen to form the hanging end of the gate; it is fitted with iron pins at top and bottom, moving in sockets sunk in the collar-set and in the top divider. The opposite post, or swinging end, is held by bolts to angle-iron riveted to the top and collar timbers. The swinging portion of the division, or gate, is strongly braced

West Au8Tkaljax Mining Practice

Fig. 94. — Swinging' Gate for changing cages

Sicips And Hafkty Ai’Pliances

18;]

together with %-iuch bolts through the two posts, and with diagoual tiinljer traces from the swinging end to the post forming the hinge. Tlie guides are cut and jointed to move with the gate. When it is necessary to open the shaft to change the cage, the top and Imttoni Imlts of the gate are released, and it is then free to swing- outwards across the other hoisting compartment. By tliis method ani])le space is afforded lo ship or unship a cage; the time required is less than that occupied under the other method; and the posts and timl)ers of the shaft are not knocked about and chipped, as nsually occurs when only the ]noval)le guide method is used. Pigs. 91 and 95 illustrate this device.

Cag’e Indicators. — Indicators, to show the driver the exact ])osition of the cages in the shaft, are attached to every hoisting-engine, and are actuated by gear in connection with the drums. They are accurately adjusted, and a skilled driver is enabled to lower a cage to any desired level in a shaft, and to ])lace it on the chairs or 1)earers without humping or jarring the occui)ants.

For shafts of shallow depths, the indicators are usually in the form of large discs, round which a hand, or pointer, travels in conformity with the re volutions of the drums of the engine. The outer edge of the dial is marked with the numl)er of each level in the shaft, and of the landing braces al)ove ground. In

West Australian Mining Practice

the majority of mines, the approach of the ascending- cage is signalled by the ring ing of a bell in the engine-room. The bell is struck the pointer when the cage is about 100 feet from the collar of the shaft, and the driver is warned to slacken speed.

For deep shafts, drum-shaped indicators are adopted. This form enables greater depths to be j-egistered than would be possible upon a dial indicator, unless the dial was abnormally large, or the motion of the pointer so restricted as not to be easily noted by the driver. In these indicators, the drum revolves and the pointer moves vertically along spiral grooves cut in the outer circumference of the drum. The numbers of the levels are marked with chalk, so as to be easily altered when alteration may be necessary owing to lengthening of the rope by stretching under its load, or by shortening through portions being cut off at times of testing and examination. From either of these causes, the marking of the indicators may become inaccurate. Re-adjustment is accomplished by the platman or some other responsible person, descending in the cage to each level, and signal ling the driver when it is perfectly in accord with the floor of each plat. The dial or drum is then re-marked.

WI:ST AUSrRALlAN MINING PRACTICE

CMAPrER XI

Signalling Aietiiods, Apparatus And Codes

Knocker Line — Electric Signalling — Call liell — Inter level Signals — Signal Code.

A PARI' from the fact that means of communication from the workers under ground to the driver at the hoisting-engine is essential to the working of a mine, the Government Regulations require that some approved system shall be adopted in all shafts where men are lowered and hoisted by means of cages, skips, or buckets. The use of one uniform code of signals is en forced by law on every mine in the fState. The code at present in use —

copy of wdiich is given on another page — is found to fulfil the desired conditions. The establishment of a uniform code of signals throughout the State is of great advantage both to mine managers and engine-drivers. Prior to its adoption

and enforcement by Government authority, it was customary for each mine to use any code that might he considered suitable. As a consequence, an engine-driver leaving one mine to take service on another might find it necessary to learn quite a

new code, or one, at least, Avhich differed in many points from the one he had pre

viously followed. This caused great inconvenience and confusion, and increased the risk of accidents, resulting from forgetfulness on the part of a new driver. But under the existing system it is immaterial how frecpientG' a driver may change from one mine to another; the code is the same in all mines and he knows it by heart. A similar advantage is afforded to the workers below ground, and no con fusion can arise owing to new men being introduced; the one and only code is fami liar to everybody. In the large mines the platman is in sole charge of the cage; he travels from level to level with it, and is the only man in the mine who is authorised to signal to the driver. No mine eni})loyee underground, who may re quire the cage to be brought to the level where he is waiting, may make use of the signals; he must wait until he can get into touch with the platman, and through him obtain the cage.

On reference to the code, it will be seen that the aim of the compilers has been to reduce the number of knocks, or rings, to the minimum. The shaft is as sumed to be divided into sections, each of which consists of five levels — irrespec tive of the depth that may exist between level and level — and for each section the signals are the same, except that the jirimary rings, or knocks, signifying the sec tion, increase with depth. The Government Regulations also require that at every shaft there shall be means for signalling from the surface to all the levels in the mine, but some difficulty has been experienced in effecting the universal adoption

i8f;

WK'r ATSTUALIAN MINING PIIACTK'E

b

Fig". 96. -Sig'nal Gong'. Elevation.

of the rule. In the opinion of many managers tliere is no special reason why the driver should repeat, or return, the signal knocks given to him from below; the only argument in its favour is, that the return signal is evidence that the driver is at his post, and that the platman’s signal has been heard and understood. A return signal, however, is not required when hoisting material, but only when men are on the cage.

In the knocker-line system of signalling, the appliances are of the simplest description. A small wire-rope suspended in each hoisting compartment of the shaft, and kept in place by staples, has its suidace and end attached to a hammer in

WEST AlTSrEALLAN MINING PRACTICE

touch with the gong. The gong is placed within easy hearing distance of the driver in the engine-room. At each level in the mine a lever is connected with the line, and serves as a pull. The weight of the line is adjusted by levers and weights at certain intervals throughout the shaft, and the power required to actuate the signal is the same at all levels.

Owing to the difficulty of tindiug a system of return signals that can be con stantly relied upon, tlie Mines Department has not hitherto enforced the regulation in regard thereto, the iMinister for Mines having discretion to grant exemption from this regulation in eases where it can be shown that, in the circumstances, such a system is impraeticalde. Se\'eral of the mines have already adopted electrical signalling apparatus at a heavy cost, and tlie following descriptions may be of interest.

Great Fingall. — The apparatus at the Great Eingall mine has been in use for some considerable time, and a point of great interest connected with it is the use of ordinary lead-insulated wires down the shaft instead of the later practice of using armoured ' cable. The cost is naturally much less, although there is greater risk of failure of insulation, especially if the shaft be very wet. The scheme has, in the instance cited, worked well without interruption, and for fairly diy mines where it is not desired to incur the heavier cost of armoured cable, it might well be adopted without fear of break-down. At the same time, the scheme outlined may be followed in wet mines, with the proviso that armoured cable be used instead of plain insulated wires.

Details of Apparatus. — The Day Dawu shaft is divided into three compart ments, two of which are for the automatic self-dunq)ing ski[)s and the third for pump and air columns, and a cage for lowering and raising men and tools. One set of electric signalling apparatus for the skips, signals from any one plat to the winding engine-driver, and the driver can, from the engine, signal to all the plats. Another set is from the cage com[)artment, and is similar to the above with the addition of a battery and extra ])ull-contact at each plat for call bells between different plats, as descril)ed later. In both the skip and cage sets the engine-bells, switches, relay and testing-push, are mounted on a board close to the driver. The main first-motion hoist for the ski])s uses one l)ell for the two compartments, but a second bell is mounted alongside with a two-way switch for use should the first bell fail. The single-drum hoist for the cage is similarly fitted. Some of the Kalgoorlie mines are fitted with separate signalling apparatus for each compartment, the bells placed on each side of the engine having different tones in order that no error may occur as to which compartment is signalling.

On the Great Fingall mine the skips are used wholly for raising ore, and no confusion has ensued on account of the use of the single l)ell. The third compartment cage for lowering and raising men and tools greatly assists to this end. The diagram of the apparatus is shown in Fig. 99. On the surface 12 Leclanche cells are placed in any convenient part of the engine-room, and the driver’s push is on a pipe bracket erected near the engine levers. In case the relay should fail, a cutting- out switch is brought into operation, in which event the full battery power is used in the shaft. The wiring in the engine-room is of 1/16-inch vulcanised

Signalling Methods, Apparatus And Codes

wire GOO M grade, rim in a casing to the front of the liousing. All the wires (four) are then cabled together and suspended from a No. 10-gange gal vanised wire, which is stretched from the engine housing overhead to a post near the shaft. They are then joined to l/lG-gange 600 M grade lead-covered

wires which are run in ILfin. pipe down the post and then to the shaft, the portion from post to shaft being buried about one foot deep in the ground. The wires are then taken (for testing purposes) into a joint-box which is made of wood, lead covered, thence down the pump and air column shaft, laid side by side in an

90

WKWr AUSTKALEAN MINING PRACTICE

()rei>on easing' .3 by lin. inside, deal cleats l)eing' screwed to them at points six feet a])art. At the to]) of each plat the wires are Ijronght ont into ordinary casing- run on

skip signals

Sic:)nols

bell

chotterton

a.

Cart) joint.

r u bbe r Ci3p

/j/y/;// V/V -y/Tzz

Seotion erf

shaft YfirinCj,

)ac4 COY - >-v I rc

vJoi nt .

Di<j-rdrT-i of :tric Sicjnol 1 1

Dcai- Dawn Shaft

Cjreat Eincoli Consol‘d Fig'. 99. Call Bell System.

the leg' of the ]>lat-set, down to the joint-box, wbicli is fixed on the side of the timber ing. The joints are ail made with about two feet of slack, and a lead cap blled with Chattei'n’s compound is fixed over each joint. The ends are tlien bunched np, imt

Signalling Methods, Appaeatus And Codes

Fig'. 100. Electric Sig'nallinc'.

Fig'. lOl.

WEST ArS9’H,ALI.VN MINING PRACTICE

Signalling Methods, Ai’Paratus And Codes

inside the l)Ox and tied there. A joint is detailed at A (Figure 99). Earth returns are used throughout and consist of ] 0-gauge bare copier-wire on each plat, connected to the nearest air or water main, hdie bells and -contacts are attached to the plat-legs as shown in sketch, and the wiring is carried in a casing to the top of the plat-end round to the joint-box. The whole of the underground wiring is of 600 M grade lead-covered wires. The skip bells (diaphragm action) are in heavy cast- iron protecting boxes, and the cage bells are in lead-covered wooden boxes. At places as it is necessary for further protection, such as crossing through plats, the wires are run through piping, the size of piping nsed varying according to the number of wires encased. In order to further protect the ap])aratus from damp, a sheet of lead, about two feet by one foot, is put at the hack of each pull-contact and then doubled over to the front. All joint-caps point ipwards as a similar precau tion.

The Call Bell System. — It is a very great advantage to have intercommuni cation between levels without the signals being repeated in the engine-room. It enables a signal to be sent to the platman (who will of course be in charge of the cage) when he is wanted at any particular level, and long delays are thus averted. By reference to the diagram of wiring (Figure 99) it will be seen that the single drum hoist (cage shaft) driver’s return signal bells and shaft wire are used for plat calls by adopting the following arrangement: —

On each plat (cage shaft) there is a battery of 12 Leclanche cells in a box fixed by brackets to the wall. The zinc is earthed and the other wire led around the ])lat-set to the pull-contact. From the pull-contact it goes back to the joint-box and joins the shaft wire at the plat bell wire junction. This means that all the bells are in parallel off this shaft wire, and on any particular plat-pull being worked the bat tery on the plat supplies current to the shaft wire, ringing the bells on all the plats. With this method in use on five levels, the drop in voltage, from the battery worked to the bell farthest away, is barely noticeable; but it depends on the rela tive resistances of the shaft wire and battery strengths, whether such a system could include many more plats. It would assist such a case if the batteries farthest apart had one or two more cells than those nearer the centre of the system.

Associated. — The following is a description of the apparatus on the Asso ciated mine: — A marine cable is suspended in the shaft by means of wooden clamps at intervals of about 20 feet. It is severed at each plat, and the ends are led out of the shaft into a cast-iron water-tight junction box, 9 by 4 inches deep, which is fastened to the cap piece, or any other suitable place. The connections between the ends of the cable are effected by means of brass screw-clamps. The plat- wiring, which consists of highly insulated wire 1-18 gauge, proceeds from these clamps through %-in. piping to the bell presses. These are water-tight and of the pull- lever type, which for further protection are placed in iron boxes fastened to the shaft timbers so as to be within easy reach of the platman while he is standing in the cage. Communication from undergromid to the surface is completed through two small relays, one for each cage, which are int into action by the platman when signalling the cage away, their function being to switch on the current from either of two batteries, with 12 cells each to the bell of each compartment of the shaft re spectively. The bells are of the large trembling type, of different tones, and are

WESa AUSTRAL LAN MINING PRACTICE

])la('e(l one on each side of tlie engiue-rooin for further distinction. Three of the strands of the cable are required for tliis portion of the system, and the remaining two are connected to the re])ly hells, one on eacli plat. These are also of the water-tight trembling type, and are ])laced in iron boxes fitted in the most snitable position on the plat. Gn receiving a signal from undergronnd the driver re])eats it by depres sing his Morse key, which causes all the re])ly bells on the levels to ring sinmltan- eonsly. The current required for this is obtained from four dozen Leclanche cells, suitably arranged for the pnr])ose.

Great Boulder. — An electric signalling system has been adopted in the Main and Edwards’ Shafts of the Great Boulder mine to a depth of 2,500 feet, with 30 polarised l)ells (29 levels) in the Main Shaft and 16 in the Edwards’ Shaft. It is claimed that the system has many advantages over any ])revions system hitherto in use.

Alternating current is used instead of continuous current, and in localities where such current is available the system consists of a transformer, four insulated wires in armoured cable, watertight ])olarised hells, junction boxes, pulls or pushes, consisting of ])latman’s pull and interifiat pull, for platman to commimicate with engine-driver and miners stationed at various levels, and vice versa.

In localities without a srqply of alternating current, a generator must be used instead of a transformer. The working of the circuit wired to illustrate the actual i)rocednre is as follows: Assuming a platman hauling at the 400 feet level, and a shift- at the 1,400 feet level requires the cage, the shift-boss simply rings the platman his number of rings by using the interplat ])idl corresponding to the level from which he rings. By so doing the hells are ringing at every level, exce])t- ing of course the engine-driver’s l)ell; the platman re])lies to the shift-l)0ss by using the interplat ])nll with the same number of rings, and calls the engine-driver by using the platman ’s pull for the level at which the cage is required. The engine-driver by using his pull replies to the platman ’s signal and lowers the cage to the signalled level. By this system perfect communication and understanding between levels will he obtained, and the engine-driver can secure the highest degree of safety. With the use of polarised hells the interruptor in the circuit, which causes so much trouble with the continuous current hells, is eliminated. By means of the trans former the high voltage current from the main supply is reduced to 25 volts, which is not dangerous to life. The saving of time in signalling allows more time for hoisting. The maintenance and working expenses are much lower than in any other hell system, and the possibilities of break-down are practically nil. This system is nndonldedly far in advance of any other method of signalling.

The ap}mratus installed on the Great Boulder mine is of the very best material, and every care was taken in fixing it. The main cable taken down the shaft is a submarine armoured one, made up as follows: From the outside jute, then steel armoured bonded, jute, prepared pa]ier, lead sheathing, ta]3e, and vulcanised rubber surround four insulated wires. Watertight cast-iron junction boxes, measur ing 15 by II by 5 inches, are ])laced at every level on the centi*e leg of the ]3lat-set. There are two Avatertight Mix and Genest pulls and one Siemens-Halske polarised l)ell placed in every level, a pull being placed on each of the legs about seven

Signal Methods, Apparatus And Codes

feet al)ove the plat, and the bell on the cap-piece of the plat. A two-core No. 16 wire armoured cable (similar to the main cable) is used for wiring the plats from the pulls and bells to the junction boxes. The engine-driver’s l)ell and pull are fixed on a board on the right-hand side, where the engine-driver is standing. The main conductors are tapped off from the sni)ply main (550 volts), and are taken to a transformer (placed in the engine-house) which reduces the voltage to 25 volts. This voltage is quite sufficient to work these l)ells at any practicable working depth. A separate circuit connected with the same transformer has been installed for signalling from the braceman to the engine-driver, and vice versa, thus making the whole system complete.

The following are the working and maintenance costs: — Transformer: No. load losses per day — 0.21 units, or 87.6 units per year at 2d. per unit — 14s. 7d. Assuming these bells work continnonsly for two hours per day, then 30 bells will consume 0.069 units, or 25.185 units per year at 2d. per unit — Is. 2.3d. Mainten ance cost — 10s. per month or £6 per annum. Total annual cost — £6 18s. 9.3d.

Signal Code. — The code of signals authorised under “The Mines Regulation Act, 1906,” is as follows: —

1 . . Sto]), if the cage, skiji, or bucket is in motion.

1 . . Hoist.

2 . . Lower.

3 . . Change to hoist from a diiiL'erent level. (This signal shall not be given while the cage

is in motion.)

4 . . IMen on. Hoist to surface.

o . . Danger Signal. The cage must not be worked until further signals arc given by ring ing eight knocks or rings, which shall signify that the cage is again free.

G . . Tools on cage. The cage shall not be moved on this signal, which must be followed

after a pause by the signal for the place to which the tools are to be sent.

8 . , (See 5 above. Cage again free.)

12 . . Accident. To be followed after a pause by the signal for the level at which the acci-

dent

has taken prlaee.

Section 1:

1 pause

. . To No. 1

Level . . Kaise or lower

cage, as case may be.

1 „

„ 2

„ 3

M

yy yy

1 „

„ 4

yy yy

1 )’

„ 5

yy yy

Section 2 :

2 p)ause

. . To No. 6

Level . . Kaise or lower

cage, as case may be.

,, 7

yy yy

O

1

.,8

1

2 „

„ n

O

n

„ .10

(hlacii succeeding

section of five

levels is designated by the

increase of tlie preliminary knock as Sec

il, ‘'3 pause 1,’’ Sec. 4, “4 pause 1,” and so on to the bottom level.)

SM-'uig Signals. — (a.) When winding from the bottom of the shaft ilirectly to the top) thereof by means of the main winding-engine; or

(b.) When winding from the bottom of the shaft to a station underground therein by means of a winch or other auxiliary winding-engine: —

7 knocks or rings shall signify firing warning,

1 knock or ring ,, „ hoist, men on

West Australian Mining Practice

19(i

Ujion receiving the signal 7 (firing warning) the engine-driver of such main or auxiliary engine shall raise the bucket or cage by giving his engine not less than one full revolution, and shall then lower it again as a signal that he is ready to hoist. He shall then stand ready at his engine until he receives the signal 1, on wliich he shall hoist carefully. He shall not return the signal 1 before hoisting.

Heturn Signals. — On receiving any signal, except as provided in the next preceding paragraph hereof, that men are about to be raised or lowered, the engine-driver shall, before beginning to wind, give return signals, repeating the signals as received by him.

When sinking is in progress by means of a winch or other auxiliary winding-engine working from a station underground in the shaft, the firing warning shall be repeated from such station to the person in charge

of the main winding-engine at the top of such shaft, and such person shall return this signal.

Bepairing Shafts. — When men are engaged in anj shaft, repairing or timbering it, special notice shall be given to every engine-driver who comes on duty on the winding-engine. The signals 1, hoist, and 2, lower, shall then be taken as meaning that men are to be raised or lowered, and the winding shall be done slowly and with great care.

Lowering Men from Surface. — Before signalling the level to which the men are going, the braceman shall notify the engine-driver by special signal that men are on the cage.

Pause. — The pause between signals in the above code shall be tlie space of time required for ringing t\vo knocks. The engine-driver shall not move the cage, skip, or bucket after receiving any signal (excepit

that of ‘‘ hoist” rvhen firing) for at least two pauses when hoisting or lowering materials, and at least six

seconds when raising or lowering men.

The foreg’oing' code is posted in a clear and legible form on framed boards, one of which be placed at each cliamlter, or plat, in the shaft, another on the brace, and another in the engine-room. No verbal commnnication up or down a shaft exceeding 60 feet in depth is permitted where cages and skips are used, ex cept through telephones or speaking-tubes properly fitted and isolated in a com partment not used for hoisting. All engine-drivers have to pass an examination, viva voce and written, by a board of examiners appointed by the Government, be fore they can receive a certificate permitting them to take charge of any winding- engine.

West Australian Mining Practice

Chapter Xii

Ore Sampling, Weighing, And Valuation

Descriptions of Various Methods employed

The sampling, testing, and valuation of a mine commence from the first day of its existence as a mine and continue daily to the end. The trial shafts that are sunk upon the lode are sampled and assayed as the Avork progresses, and every drive and crosscut opened up is subjected to the same searching investigation. Even in vertical shafts sunk in the hanging-wall country away from the outcrop, the same watchfulness obtains, and Avhenever a change of rock or any small veins are encountered and believed to contain values, samples are takeu and assayed. Later on when crosscuts and drives are commenced, sampling is methodically conducted. The drillings from dry holes are assayed in samples representing sections of two feet or less of holes. After firing, the face and sides of the cut are sampled, and samples are also taken from each truck-load of ore. Drives are dealt Avith in the same way, and their sides are bored at inteiwals to ascertain if pay-ore is lying hidden behind the walls. The place from Avhich the sani]fie was taken is measured from some datum point, and the locality, name of Avorking, AAndth of ore exposed, width of each section sampled, existence of any side Aeiu, fault or disturbance, to gether Avith the assay value of the sample, are carefully recorded in a hook kept for the purpose. In addition, an assay plan is prepared on Avhich the workings of the mine are diaiAvn to a scale, and the Avidth of the ore passed through and the value of the sample are marked in figures. This plan consecpiently becomes a chart of the Amine of the mine, and it is as indispensable tt) the manager as Avoiild he the chart and soundings of a water-way to a mariner.

Winzes and rises are sampled as each cut is taken out, or at ecpial distances across one or both ends, and prospecting bore-holes are run out at stated intervals to exi)lore the adjacent lode, the drillings being assayed, as in drives and other workings. In winzes it is frequently impossible to obtain a reliable sample from the actual bottom of a cut, as it would be difficult to get a clean face for the pur- l)Ose, and there would be some danger that ore from higher up the winze may have been shaken down when firing, thus vitiating the sample. It is, therefore, better to take samples from the ends of the winze, one at the top and one near the bottom of the cut.

In slopes the face of ore is sampled in sections from one foot to three feet in width, and a bulk sample is also taken right across the full width of the face, as a check upon the sections. The positions of the faces sampled are fixed by their dis-

West Australian Mining Practice

tances from a winze, rise or other point, and from the walls of the lode, and the height from the level below. As the ore is drawn from the chutes each truck-load is sampled, the sample being thrown into a box kept for the purpose. At the end of the eight hours shift the samples are sent up to the assayer. Each box is marked with the number of the level, the section in which the stope is being worked, and the particular chute and number of trucks from which it was drawn. The results of all the assays are duly recorded, and are subsequently used, in conjunction Avith those obtained from development work, as a basis upon Avhich to estimate the value of the remaining ore.

Special men are detailed as sanq)lers througliout the mine. In addition, the mine manager may take samples from places upon which he requires ])articular in formation, or which may need special attention. In the ordinary course of sampling the assay of one Avorking place may be found to alter suddenly, higher or lower, from that of its immediate predecessors. A second, or check sample is then taken, and, if possible, the cause of the change ascertained.

In driving on the course of a lode it is commonly found that the gold con tents are not evenly distributed throughout the ore. The accepted ])ractice is to sample the face in sections by cutting grooA"es across the laminations of the ore- body, thus affording a ready means of accui-ately locating the position and Auiriation of the values of a wide face. It is essential that the greatest care should be exercised to ensure that a reliable sample is taken, and, in order to obtain this re sult, the groove cut out over each section should l)e of an average size throughout its length. In soft material this method presents no diliiculty, luit in hard material, except in special cases, the time and expense iiiA'olved render it impracticable. The sample cut is therefore taken as eAmnly as circumstances Avill permit Much has to be left to the judgment of the sampler, and the import ance of employing trustAvortlqy and experienced officials to carry out this Avork cannot be overestimated. In some instances Avliere abnormally high values appear in an assay, their presence may be attributed to the accident of some specially rich particle having been retained. These exce])tional values are frequently en tirely discarded, or at least, reduced to about the normal higli Auilue of the place from Avhich the sample was taken. This })ractice does not, hoAvever, apply to Ioav assays; these are alloAved to remain, on the p]-inci])le that a Ioav average of the bulk of the ore treated is more likely to result than a high one. It is obvious that how- eAmr closely and carefully the Avorkings of a mine are sampled and assayed, the quantity tested is the merest fraction in comparison to the bulk of ore exposed for treatment; and that the Auilues are not much more than an api)roximation of the actual contents. This is particularly the case in mines such as those herein des cribed, where variations in value occur in the lodes at short intervals. The caution — born of experience — of a manager, induces him to lean to the side of the medium and Ioav values in his mine, as being more in accord with the general aver age likely to be |)roduced from the treatment of the ore in bulk.

Ill the jiriiicipal mines of Western Australia the methods of sampling and valuation agree in general ])rinciples, and the slight variations to be noted here and there arise chiefly through the variable character of the ore-bodies dealt with. That the methods are reliable is demonstrated by the fact that the annual results from the

Gee Sampling, Weighing Anh Valuation

different mines approximate closely to the estimates of vaJnes |)reviously given forth. Specific examples of the methods of sampling, weighing, and valuation are here added.

Great Boulder Proprietary. — The ore in every truck, before being hoisted to the surface, is sampled by a “grab” taken from it. The trucks are all the same size, and contain l,5G81b. of ore. From these samples and weights are obtained the value and quantity of ore removed from each section of the mine, and these data are used in valuing ore reserves every six mouths. Two automatic samplers are used in the mill to check the mine sampling. The crushed ore sampling corresponds very closely with the grab sampling when extended over the month.

-Great Boulder Perseverance. — Faces of drives are sampled in 2-ft. sections across each fresh cut, and at right angles to the underlie of the lode. Bulk samples are also taken. Crosscuts are sampled on each side in sections of three feet. Dril lings from holes in each cut are kept over sections of 2-ft. each and assayed. Stope faces are sampled in 3-ft. sections, and bulk samples taken from across the whole width of the face. In drawing off ore through the chutes, a sample is taken from every truck filled. No ore reserves are specifically valued unless opened on three sides. The tonnage of ore sent to the mill is arrived at I)y weight and number of trucks passing over an automatic weighbridge after the ore has passed through the rock-breakers.

Associated. — About 2,205 underground assays are made monthly. Drives are sampled over the face and back of each cut, in sections suitable to the ore-l)ody, and samples are also taken from the trucks. Sample holes are drilled to depths of five feet on each side at intervals of about ten feet. Crosscuts are sampled on sides and back in 3-ft. sections, as well as the drillings from the first bore-hole. Samples are taken from the stopes in the face and again from the ore in the trucks. 'Ilie mill tonnage is measured by filter-presses, the Aveights of the cakes l)eing frequently tested on platform scales. Frequent tests are also taken for loss of weight in roasting.

Kalgurli. — In drives, after firing out a face, a bulk sample is taken from the broken ore strewn along the drive. Truck samples are also taken Avhen this material is l)eing removed. In crosscuts, sanqiles are taken from the face, from eacli side of the cnt, and from the trucks. Stopes are sampled in 2-ft. sections. Samples are also taken from each truck filled from the chutes. The valuation of ore-bodies is arrived at by the average of the samples as taken above. Each lens of ore is valued separately. All ore sent to the mill passes over a Aveighing machine. An antomatic counter records the numl)er of loads sent to the mill.

Ivanhoe. — Drives are sampled every three feet and occasionally in sections of one foot each. Sample bores, fifteen feet apart in the walls, are sampled in 3-ft. sections. Winzes and rises are sampled every two feet across the ends. Crosscuts are side-sampled throughout. Leading stopes are sampled on the faces and from the trucks at every cut, and stopes are sampled from the chutes as trucking proceeds. Ore reserves are computed when developed on three sides, and each 100-ft. section is kept separate on each level in regard to value and tonnage; the average value is then taken for each lode, and a grand total is shoAAm. A ton of 2,000 11). is estimated to be contained in 11.6 cubic feet. Estimation of tonnage treated is made solely

West Australian Mining Practice

from tlie residues from lilter-presses aud cyanide vais discharged, less the amount of moisture. Tallies of trucks discharged into plat ore-bins and of the number of skips raised are also kept, Init not considered reliable for tonnage, as they invari- abl)' give higher results than the discharge from the treatment works.

Lake View Consols. — In crosscuts, two samples are taken for the length of each cut, one on each side of the crosscut. The position is measured from datum point by the sampler and checked by the surveyor once a fortnight. When ore is met with, the sections containing values are re-sampled, the ore being kept as distinct as possible from the barren rock in order to determine the exact width and value of the ore itself. Values are often erratic and the difference between two sides varies considerably. In recording values, therefore, the average of both sides is taken as being the correct value. Drillings from one of the holes in each face are also sampled. Before completely stopping work in a crosscut, a hole is bored in the face to a depth of 10 or 15 feet and the drillings are sampled in 3-ft. sections. The faces of the drives are sampled after each firing at right angles to the strata. Samples are taken in 30-inch sections in a drive five feet wide. These samples are recorded as east and west, according to their position. Distance from datum points is also recorded. Sample holes bored at intervals of fifteen feet in the sides to depths of five feet are sampled in sections. When, owing to the width of the drive, the holes cannot be placed at right angles to the ore-bod}, the necessary correction is made in recording the depth. Should any values be revealed, the walls are subse quently stripped ; the stripping face is sampled and the value is added to the corresponding drive samples to show the correct width and value of the ore-body. Rises and winzes are sampled after every cut, across the ore in 30-in. sections, and the results are recorded as for drives, etc., the measurements being taken from the drive below, in the case of rises, and from above in winzes. In the latter the samples are taken across the end as close to the face as possible. In both rises and winzes bore-holes are run into the sides and sampled in 24-in. sections. The distance of face from datum point and from level below is recorded. Six-feet holes are bored in the sides at intervals of every fifteen feet along the stope. Should these holes disclose any values the width of profitable ore is stripped off and the face sampled and the results are recorded as stripping samples. These stripping widths and values are added to the corresponding stope width and values to obtain the total width and correct average value. Owing to the method of stoping adopted (shrinkage) the face values cannot always be used as a basis for ascertaining the correct value of the ore extracted from day to day. The ore is, therefore, sampled as it is trucked away, a sample from each truck be ing thrown into a box provided for the purpose. The number of trucks taken from each chute, and the number of the chute from which they are taken, are duly re corded along with the assay. The following method is adopted for computing values of ore-bodies in drives, rises, and winzes : — The average at each face sampled is obtained by first multiplying the width of each section in inches by the value in shillings. The sum of these products is then divided by the total width of the face in inches, giving as a result the average value over that face. Next, the total width of each individual face is multiplied by its average value, and the total of these, divided by the sum of the widths, gives the average over the whole length of the

ORE SAMPLING, WEIGHING AND VxVLUATION

drive, etc. The sum of width divided by the number of faces gives average widths. The values and tonnages of Shocks of ore ai'e readily computed (for purposes of ore reserves) from the data thus obtained. TTie tonnage and value of the ore mined and extracted are recorded in a series of books. In the Thaick Book is kept a daily record of the number of the trucks of ore extracted from each stope. The ore de rived from development — together with the waste rock — is also entered in this book. The truck-loads are converted into tons, each load being equi\’alent to U.75 of a short (2,UU0 lb.) ton. An ac'-ount is kept in tlie Gre Extraction Book for each stope and development item separately. The tonnages from the Truck Book are entered here, together with the estimated value as obtained from the truck samples, also the gold contents in pounds sterling. The value of the actual gold-contents is obtained monthly from the metallurgical sheet, and the estimated contents are corrected accord ingly. In the Stope Assay Ledger the stope samples are recorded. The average value of these samples is ascertained monthly and the ore lu-oken during that period is assumed to be worth that value. A similar book is used foj- recording the samples from development items. The different data thus obtained form the basis of the Ore Extraction Ledger. On one side of this ledger ai'e entered the data con cerning the broken ore and ore in place, and on the other side particulars of the ore extracted. The first entry is that of the estimated tonnage and value of the particular stope, which are entered as broken ore and ore in place. The total ore broken in the stope during the month, and the estimated value of the same, are entered every month, the tonnage being estimated bj survey and the value by face sampling. The ore extracted, together with its value, is entered every month on the opposite sine of the ledger. At the end of every half-year the ledger is balanced, the balance of the ore in place being the original tonnage and value estimated, less the tonnage and value of ore broken during the period, and the balance of the broken ore being the total ore broken, less the amount extracted during that period. These bal ances are checked by re-survey, and, if necessary, adjusted in order to start off the next half-year with correct figures. The truckers hand in their tallies from various i)laces, and the platman also furnishes a tally of the number of trucks or ski])s hoisted for the shift. These check each other. A standard weight of ore i)er truck is determined and tlie calculation of tonnages from various places is worked out accordingly. Allowance is made for ore in bins at the end of each month, and a comi)arison of battery and nnderground tomiages shows only a slight difference over a month’s run.

Great Fingall. — In drives every fresh face is sampled. Where pay-ore is being followed, the sample is taken from the top and bottom of the face, as values in this mine are inclined to rnn in layers. The face is taken in 3-ft. sections. Drives are usually placed on the foot-wall of the lode, and at every fifty feet a crosscut is run into the hanging-wall. These crosscuts are sampled on both sides, and the width and value of the lode ascertained. Rises and winzes are on the hanging-wall and are sampled on both sides. Crosscuts are put in at intervals to the foot-wall and sampled, as in crosscuts in the main level. In stoies each face is sampled in sec tions of from four to five feet, and allowance is made for waste rock. AVhere it is noticed that the wall is likely to flake, allowance is made in order to adjust the decrease in value caused by the nnavoidable breaking of valueless rock with the

West Australe.N Mining Practice

pay-ore. The ore is divided into two blocks l)y the develojnient work, and tonnage and value are computed hy tlie resnlts obtained from the al)ove methods of sampling. A record is kept of all ore trucked and of skips hoisted to the ore-bins. The tonnage drawn from the ore-bins by the belt-conveyor is weighed hy the automatic weigh bridge in connection with same. That drawn away l)y aerial tram has an auto matic counter, which records the number of trams sent to the mills in this manner.

West Australian Mining Practice

2U

O

Chapter Xiii

DIAMOND DlilLLLNG

Particulars of Macliiues — Size of Core — Deflection of Bores — Costs.

Ni the mines where prospecting with the diamond-drill is practised the work is nsnally done on contract hy owners of drilling plants, who maintain staffs of skilled workmen. The machines in nse are the Sullivan Company’s “H” and “E” drills. The “H” is capable of boring a hole of 1 -in. diameter for a distance of 1,000 feet vertical or horizontal, and prodncing a core 1%-iD- in diameter. In tliis machine the advance or “feed” of the drilling bit is ])rodnced hy a single cjdinder hydranlic piston, and the feed can by this means be adjusted closely to the requirements of the rock throngli which the drill is passing. The motive power

used below ground is electricity or compressed air. The consumption varies with the nature of the rock and the distance to which the hole is bored. For the 100 feet the power required is estimated at 110 cubic feet of free air per minute, and twice as much as that for 500 feet. Power and water are supplied by the mine in which the drilling contractors are at work. The. supply of water required is approximately 200 gallons per day, but this depends upon the character of the country. If it is solid rock without 0])en seams or veins, almost all the water is returned from the hole ; but in fissured rock, or that in which soft seams and veins are encountered it may happen that no water will be returned. The loss in that case would be approximatey from 2,000 to 3,000 gallons per twenty-four hours. In mines where the natural supply of water is limited it is necessary to make arrangements to retain the outflow by constructing a well-hole or shallow dam. The hydranlic force used to advance the rods is supplied by a |mmp, or in some cases the water is led into pipes from some reservoir situated in the u])per levels.

Fig". 102.— Sullivan Diamond Drill on an angle hole l.SOO feet deep.

The “E” drill has a ea])acity of 400 feet, and is fitted with a screw friction- feed instead of the hydranlic feed. The diameter of the hole is - in. and the core -|g- in. The light weight and compact form of this drill make it very suitable for ])rospecting underground in confined spaces. The supply of power and water

2(4 West Australian Mining Practice

required is about equal to that of the “H” drill. The drill is operated by two men per shift of eight hours, and the whole equipment is supervdsed by a foreman, who also attends to the setting of the diamonds in the crown, and keeps bits ready for use as required. The setting of the diamonds in the bit calls for the exercise of great care, so that each diamond may do its proper share, and no more or less, of cutting. The projection of the diamonds beyond the surface of the bit is accurately gauged. The bit, or crown, is formed of soft iron of special quality. Seatings to hold the diamonds are drilled at the required distances apart, and are lined with a thin layer of copper. After the diamond is gauged for position the iron of the bit is carefully driven round it by hammer and punch, pains being taken that every portion of the enclosed surface of the diamond is brought into firm contact with the iron. The life of a bit depends upon the nature of the rock bored, and too much wear is not permitted, both on account of the danger of losing the diamonds, and of boring a hole of varying diameter. Of the two men at the drill, the leading man is known as the “runner” and the other as “helper.” On the experience and skill of the former depends the success of the operations. By the sound and the feel of the rods, and from the reading of the pres sure gauge, the runner can tell the nature of the country through which the drill is pas sing and what is hai)pening at the lower end of the rods. According to the correct ness of the reading of the various signs does the Avork succeed. The core of rock produced by boring passes iq) through the hollow bit into the core-barrel ; this is the lowest length of the rods and is usually about ten feet long. Just above the point where the bit is screwed on, core springs are set inside the barrel, so that as the core passes into the barrel, it is prevented from slipping out when the rods are withdrawn to the surface. The 10-ft. barrel represents the longest core that can be produced without withdrawing the rods, and in a few instances an unbroken length of ten feet of core has been secured. As a rule, however, the rods have to be drawn much oftener than every ten feet owing to various mishaps in boring. The advance attained in boring a hole depends upon the nature of the country and may vary from six inches to twenty feet or more in eight hours. The best rock for speed is one that is solid but not excessively hard, capable of producing long- lengths of unbroken core. In passing through a lode, or country, of soft nature, speed would have to be reduced, or otherwise the rotation of the rods would grind up the core and cause it to be washed up with the return water. When it is ex pected to pass through lodes of soft nature, care is taken to secure the drillings brought up with the water for purposes of assay. When it becomes necessary to empty the core-barrel the rods are withdrawn and the lower end of the barrel is unscrewed at a joint just above the springs. The core may issue in lengths varying from less than half an inch to several feet. Each piece is laid in order of its with drawal in a box made for the purpose and capable of being locked up before leav ing the hands of the runner. The full boxes are taken to the surface by some one specially told off for the purpose, and are carefully examined and sampled. If any lode formation is visible, portions are taken for assay. On some mines the whole of the ore portion is ground up for a sample, in others only selections of ore are assayed. The core boxes are from three to four feet in length; slats of wood divide them lengthwise into compartments of depth and width suitable to the diameter of

Diamond Drilling

the core. Small blocks of wood, or otlier inarks, are inserted to show the deptli from whicli the core has lieen derived. These ai-e placed at each draw of the rods and they also show what length of the core is missing; this is necessary hecanse the core produced is never quite in accord with the actual depth of the hole unless in exceptionally good country where the core comes out in long unbroken lengths. In soft country where the core may have been ground and washed up at points where veins occurred, the discrepancy between the de])th of hole and length of solid core produced may be very considerable. The })articulars of the core ol)tained are entered in the book ])rovided for the ])urpose. The register shows the locality of the bore in the mine, its k'earing, inclination, advance made daily, total deiAh of hole, core produced, depth from surface, character of rock passed tlirough, uature of ore found, width of vein, and assay value. On compietiou of the bore a diagram is usually drawn and marked in accordance with the register. This affords easy method for future reference.

The tendency of the rods to deviate from the course designed for them creates an element of uncertainty as to the exact spot at which boring ceased. In some proved cases the deflection has been found to be very great, and it is difficult to prevent it. Owing to the great length and small diameter of the rods a consider able curve may be made, and it is not always possible to determine whether a deviation has taken place. If the deflection is comparatively abrupt — caused per haps by the bit being led along the edge of small cracks — the pressure gauge on the hydraulic feed cylinder will indicate that something has gone wrong, Imt a gentle deviation produced by the gradual slipping of the lut up or down, or along the bedding-planes or heads of the rock, may be continued for great lengths without be ing detected. In one known instance, where a horizontal bore-hole was sub sequently followed by a crosscut, it was found that the rods had made a double curve, first northerly, then back to southerly. When a serious deflection is mani fested the practice is to draw the rods, fill the hole with cement up to and beyond the point at which the deflection was supposed to commence, allow it to set hard, and then resume boring. The result usually is that the rods are carried past the point of previous deflection and continue in a straight course. In vertical and horizontal holes the rods are more apt to sli]) on the strata than if the bore is in clined so as to pass through the strata at right angles to the dip. It has beeii found in practice that the rods have a tendency to turn in a direction at right angles to the strata in the rock.

By careful observation and exhaustive tests extending over several years, it has l:)een proved that the deflection of a borehole can be reduced, and in some cases ]n’evented, if proper care is taken by those in charge of the work. Tests were made oil a great variety of holes varying from vertical to horizontal and including many “uppers” or angle-holes above the horizontal. It was found that in most cases the deflection was due to the great difference between the size of the holes and of the core-barrel and rods used in drilling. In some instances, a clearance of I4-in. was allowed on the diamond hit at the start of a deep hole, which resulted in the cutting of a hole %-in. larger than the diameter of the top of the core-barrel. This allowed the top of the core-barrel to lie over on one side of the hole and about ;L in. out of true line when the barrel is new, increasing as the top of the l)arrel becomes worn.

WEST AUSTRALIAN Ml NINE PRACTICE

L'nder such conditions tliere was every tendency for the bore to deflect. Where the difference betAveen the size of the bit and the core-lAarrel was reduced to within As-in. it Avas found that no very serious deflection took |)]ace. Subsequently, l)y reducing the difference in size between tlie bit and the core-barrel to -1 -in., the to]) of a 10 ft. core-l)arrel could not get more than --in- out of line, and where no excessive wear o(‘curred at tlie to]) of the barrel, the hole was found to go practically straight. The \vea]‘ at the top of the l)arrel cannot, lioweAmr, be altogetlier avoided and, for some undiscovered reason, it takes ]flace on one side only, thus graduallA' increasing the error from the true line.

During inAmstigations made on the Kalgoorlie goldfield to ascertain the causes of deflection, one imi)ortant point Avas discovered which helped to solve the problem, ami tliat Avas, that tlie lioles that deflected Avere found to have lieen bored with badly Avorn core-barrels and rods. By fitting a guide at the to]) of the barrel to keep the liaiTel in true line with the hit, and so designed that the wear would come on the guide, and not on the barrel, the Avear Avas found to he Amry light and could he readily taken u]). By the adoption of this deAuce Amry slight deflection Avas possilile, and, in some cases, it Avas Avholly prevented.

More than one ap])liance has been inAmnted for the purpose of surveying bore holes, but, so far, the results have not been entirely satisfactory. The diamond-drill has been of great assistance in testing conntry lying outside the main ore-channels, and for this Avork it is of course Amry much cheaiier and more expeditious than cross- cutting. In the Kalgoorlie mines the cost of Iioring amounts to ten or twelve shill ings ]ier foot, exclusive of cost of power. Where ore-bodies have been indicated by the drill no great trouble has been ex])erienced in sul)se(|uently finding them in crosscuts or driAms, but Avhere no such indications liaAm been met, there must ahvays remain some uncertainty as to Avhether an ore-I)ody may not have been missed.

West Australian Mining Practice

l'07

Chapter Xiv

Explosives

Composition — Purity — Chemical and Physical Examinations — Safety Fuse — Fumes — Quantities and Value of

Importations.

ON any large iiiiiiing field, close attention must necessarily lie claimed Iiy methods of ore lireaking. In the endeavour to keep down working costs the most economical application of the enormous power conhned in the disruptive agents used demands close and constant study. Nor is economy the only considera tion — the safety and health of his workmen is recognised by the mine manager as one of his greatest responsibilities, so that he has a double task to perform. He has not only to find the explosive most suitable to his requirements and the conditions most favourable for procuring the maximum work from its ex]hosion, but he has also to see that safety is not sacrificed to profit and that the explosive is of such a character that it will not, in any way, cause any risk to the life or general health of the miners. It is true that in many respects the latter duty is one which he cannot discharge fully unaided, and which in this country at any rate falls very largely upon Government Ins])ectors, but such assistance as can l)e given by the officials is always at the disposal of mine managers and is very gladly and fully availed of by them. There is the more reason for this co-operation in that the purity and safety of the explosive is also of some importance from a monetary point of view, and is not without influence upon the dynamic effects of the explosive.

It will be seen as the matter is opened u}), that to a great extent, these two points of view, if not actually identical, are at any rate largely com]lementary and that power depends upon purity, using the latter term in its widest possible sense, and the mine manager will be the first to recognise that safety to his workmen is as important a consideration as economical working. Much has already been done by such mutual co-operation between the mine managers and officials in this State. The technical man, by ])ointing out the theory of ex])h)sives, hel])s the miue manager towards better ])ractical results and, himself learuing from the difficulties exjterienced in the mines and acting as an intermediary between manufacturer and consumer, he can often help in the ini])rovement of the explosives used and their adaptation to special ends. There is no doubt, for instance, that in Western Australia only the highest quality of explosives can kee]i a footing, and one reason for this is the stringent supervision exercised over them. Mr. Oscar Guttman in his recent book “Twenty years progress in Explosives, ’L"; refers to certain special imiu’ovements which have been made “on account of the very stringent regulations in this country (England),

<“i Whittaker & Co,, London, 1909.

\VI]!ST AU8iailALiAN AiiNlNU PRA0!TICK

aud more es})ecially in Australia and South Africa,” while there is yet much to he done in the same direction. It may therefore be of interest to describe something of the restrictions imposed and of the supervision exercised, dealing hereinafter, or as they arise, with certain practical considerations Avhich this supervision has called forth or can suggest for future enquiry.

In the first place no explosive can enter the vState until it has been placed on the “Authorised List of Explosives.”''*! This is a list of all the explosive compounds which have been a})]>roved of with the composition which must be adhered to in their manufacture. Before any ex]fiosive is placed upon this list it is carefully tested as to its safety for transi)ort, storage aud use. It is tested, for instance, as to its sensi tiveness to a glancing blow, such as it might easily receive against the side of a bore-hole iii the act of charging a shot. Its behaviour under percussion and friction is also studied so that some idea may be gained as to whether it is reasonably safe to handle under the jarring and luunping which it is certain to receive under extended trans])ort. It is also watched as to its behaviour under moist and hot atmospheric conditions, and carefully tested as to its chemical purity and liability to undergo chemical changes or deterioration. When once an explosive has been put through this ordeal and has stood it satisfactorily it may be imported and distributed, provided that the formula i)resc]'ibed is adhered to. On the authorised list of Western Australia there are some 60 explosives but the majority of these are not in general use. In the old days when gunpowder was practically the only explosive used for all purposes much less care was called for, since the effect of most of the working conditions which it would have to encounter would l)e to render it more, rather than less, safe in handling. A moist atmosphere, for instance would tend to render it inert, and the hole in which it missed fire could l)e easily drowned with water and all subsequent danger averted. With the advent, about 50 years ago, of what are known as the “high ex}(losives,” an altogether different state of things came into existence. Many of these explosives are highly complex chemical compounds, having shut up within them almost uncontrollable ])Ower, and yet, from the very complexity of their composition, liable to lie seriously affected by comparatively slight changes in outside conditions. The changes set up by raised temperatures for instance, are such as to render the material far more dangerous than before. This is true of the nitro glycerine explosives, which form practically the only class used on Western Australian mining fields, and which comprise blasting gelatine, gelatine dynamite, gelignite and dynamite.

Composition of the Principal Explosives. — The principal ingredient in all the explosives used is nitro-glycerine, which is a limpid oil formed by the action of a mixture of nitric and sulphuric acids upon ordinary glycerine. After the chemical action — which is a very violent one unless most carefully controlled — has taken place, the nitro-glycerine is washed repeatedly to remove from it the traces of acid which might be left over from the first operation. The ]iresence of these acids is dangerous, because in the finished exqfiosive they may set iq) chemical action, with disastrous results. Tlie ]iurified nitro-glycerine is then mixed with other snlistances so as to make u]) tlie e\qlosive in a solid form. The liquid nitro-glycerine is so sensitive to

In this, as in many othir diiections, tlia methods and liigh standard set by H.M. Inspectors of Explosives in England are followed as closely as possible lor as far as they are applicable to local conditions.

EXPl.OSIVES

percussion and friction that it would be highly dangerous to transport it or attempt to use it alone, and when first introduced it was the cause of many disasters. The sul)stance with which it is mixed varies according to the explosive to he manufac tured. In the old red dynamite, or dynamite No. I., which has now almost gone out of use in this country, it was simply absorbed by a quantity of infusorial earth or Kieselguhr, an absorbent earth consisting of the siliceous skeletons of minute diatoms, and, therefore, often called diatomaceous earth. This earth is in itself quite inert, and was simply used to form a plastic mass which could be more readily and safely handled than the nitro-glycerine ; it took no part whatever in the explosion of the dynamite.

A great advance on this was effected when, instead of Kieselguhr, the nitro glycerine was associated with nitro-cellnlose. Nitro-cellulose, of which one form is guncotton, is made by the action upon cotton fibres of the same acids as are used in the manufacture of nitro-glycerine, and when this is incorporated with the nitro glycerine it shares in the explosion, instead of acting as an inert base like Kieselguhr, and thus great additional power is gained. This mixture constitutes blasting gelatine. In the manufacture of nitro-cellulose the same precautions have to be observed to get rid of any traces of acid which might be left in the mannfactured product and this is still more difficult to avoid than in the case of nitro-glycerine. In blasting gelatine, therefore, we have a mixture of two highly complex chemical compounds, and this fact increases the possibilities of chemical change, with its resultant deterioration and danger. The other two explosives, gelatine dmamite, and gelignite, are intermediate in a manner between the two already described ; they each contain nitro-glycerine and nitro-cotton, mixed with a certain proportion of wood pulp, or wood meal, and nitrate of potassium, the object of these being to produce effects of intermediate power and character between those of blasting gelatine and dynamite. It is obvious that the substances here mentioned cannot by any mechanical methods of mixture be rendered a perfectly homogeneous mass. In blasting gelatine the nitro-cotton dissolves in the nitro-glycerine to form an apparently uniform jelly, but in gelatine dynamite and gelignite perfect homogeneity cannot be obtained. Though this may appear liypercritical it is a point of some practical importance as will be seen later. The composition of these four explosives is shown in the following table. Their more detailed composition is shown on page 220 : —

I-’er cent.

Rla.sting G-elatiue . .

Xitro-glycerine . .

Xitro-cellulose

Gelatine Dynamite

blasting’ Gelatine

Absorbent Powder

Gelignite

Blasting Gelatine

Absorbent Powder . .

Dynamite

Nitro-glycerine . .

Kieselguhr

The “ Absorbent Powder ” is a mixture of wood-meal and nitrate of potassium, with small quantities of carbonate of calciurn

AVEST AUSrRALIAN MINING PRACTICE

The object of these chemical mixtures is to ]roduce a compoiiiid which, under certain exciting impulses, can be transformed from the solid state into a relatively enormous volume of gas, with a simultaneous evolution of immense cpiantities of heat. This heat, acting upon the volume of gas originally formed, causes it to expand, and it is this sudden expansion from the relatively small volumes of solid to an enormous volume of gas which gives rise to the disruptive power of the explosive. The following table gives some particulars of the chemical and physical changes which occur and of the energy developed when some well-known explosives are detonated. These figures are the result of some of the l)est recent experimental work as carried out by C. E. Bichel and considerably modify previous conceptions of what occurs: —

Explosives.

Explosive.

Nature of

Gases produced.

Temperature of explosion (Centigrade).

Cubic Inches of gas formed

Rate of Detonation (Feet per second).

Initial pressure of explosive when detonated in its own volume.

inch of Explosive.

Lb. per sq. in.

Tons per sq. in.

(Degrees)

Gunpowder

Carbon Dioxide

Carbon Monoxide Nitrogen

59,866

Blasting Gelatine

Carbon Dioxide

Nitrogen

Steam

Oxygen (small quart)

25,262

253,216

Gelatine Dynamite

Carbon Dioxide

Nitrogen

Steam

22,966

194,075

Carbon Dioxide

Dynamite

Oxygen

Nitrogen

Steam

22,368.5

179,840

Guncotton

Carbon Dioxide

Carbon Monoxide Hydrogen

Nitrogen

Oxygen

20,810

158,264

In dealing with explosives there are two matters to which the greatest atten tion recpiires to be ]iaid: —

1 . The correctness of their composition.

2. Their purity.

Correctness of Composition. — The com])Osition of ex])losives used in Western Australia as disclosed by periodical analysis is extremely regular, doubtless owing to the rigid restrictions imposed by the Exiilosives Act. The effect of this regularity in composition is two-fold — in the first place it implies uniformity of result under the conditions of use, and secondly, it ensures the formation of gases during the explo sion which shall be least harmful to the workman. This (piestion of gases and the eff'ect of the com])osition of the ex])l()si\'es is of such ini])oi'tan(‘e that it will be specially dealt with later.

Explosives

Purity. — The principal im]nirity to I)e looked for in nitro-glycerine compounds has been already indicated. It is the acid which is left over from the process of manufacture of the nitro-cellnlose and the nitro-glycerine. If excessive quantities of these acids (principally nitric acid) remain in the finished explosive, they are apt to give rise to chemical action under the conditions of storage. The explosive may he apparently in good order when first issued from the factory, l)nt when placed in a magazine, es]iecially under semi-tropical conditions, it rapidly undergoes deteriora tion. This becomes first ap])arent by the change in colour of the explosive ; it gets darker, and, at the same time, instead of being an elastic mass regaining its original form after ])ressnre with the fingers, it becomes sticky and plastic. As deterioration proceeds in many cases it gives rise to the separation of nitro-glycerine from the com pound ; this shows itself as an oily layer on the paper wrapper, through which it gradually exudes in an increasing amount, until it may find its way through the pa])er altogether. The exudation of nitro-glycerine can also be caused by other means, which will be referred to subsequently. Throughout this series of physical changes, the explosive, when tested, shows increasing amounts of free acid, which are caused l)y chemical decomposition of its constituents. If this decomposition be allowed to proceed indefinitely it may ultimately lead to such violent chemical changes in the explosive, that it will become heated and eventually inflame. This is what is known as spontaneous ignition of an explosive, and if a large mass of such an explosive were to become ignited a violent explosion would be inevitable. It is, however, rarely that matters proceed to this extreme length — one might almost say never, under present conditions of inspection and supervision. There have been several serious disasters which have been attributed to this cause in the past, but from the nature of the ease it is impossible to prove absolutely the cause of such an explo sion, and, at any rate with present-day knowledge and the restrictions imposed, which are based upon that knowledge, the probabilities of such spontaneous ignition should become more remote. Not only, however, is an explosive which has thus decomposed dangerous on this account, but it is undesirable also from the consumer’s point of view. An explosive which has deteriorated in this manner is almost invariably found by experience to give rise to fumes of a noxious character during blasting, so that there is no question that the most important test that can be applied to nitro glycerine compounds is that for the detection of free acid. Over 2,000 tests of this character are annually made by the Government officials.

Chemical Examination.— The method of testing may be of some interest. A small quantity of the explosive is cut out of a cartridge or “plug” and ground up in a mortar with twice its weight of French Chalk (Kaolin), special precautions being taken during the process. The loose granular powder thus obtained is placed in a test tul)e, and this is immersed in a suitably constructed water bath, which is kept at a constant temperature. At the same time there is inserted into the month of the test tube a cork through which passes a small glass rod, carrying at its lower end a little strip of filter paper, which has been impregnated with a mixture of starch and potassium iodide. The preparation of this test pa|ier is one of the matters demanding the most critical care in connection with the whole process, and certain improvements in its ])re])aration were introduced a short time ago by the Home Office Inspectors as the result of Western Australian experience. The top of the slip of paper is moistened

West Australian Mining Practice

with glycerine solntiou, so that about half of the slip is moist and the lower half is dry. As the heating of tlie explosive in the water bath proceeds there gradually appears on the test pai)er at the jnnction of the wet and dry portions a slight brown tinge. This is dne to the action of the free acid in the explosive, which is driven off by the heat, and lodges upon the test paper. This tint gradnally darkens and extends, and when it has reached a standard depth of colour the test is completed. This standard tint must not be reached in less than 10 minutes. This test is known as the “ heat test,”'* and has a very wide application. Most of the explosives imported into Western Australia give heat tests varying from al)ont 12 to 25 minutes and this may he considered as representing a very fair degree of ])nrity, when it is remembered that the test is made at the conclusion of a long voyage through the tropics.

The results of the tests made here are closely studied the mannfactnring firms in England and on the Continent, which is continually making for improved manufacture and solution of problems arising in practice. It is obvious that if any thing were added to the explosives which could he driven off during the application of this test, and which would nullify or delay the effects of the acid upon the test paper, it would have the effect of making the explosive appear of much better cpiality than it really is. Among other substances which would have this effect is perchloride of mercury (Corrosive Sublimate) and great excitement was caused throughout the explosive world when the fact l)ecame disclosed early in 1907, that large quantities of explosives imported into and manufactured in England contained sufficient quantities of this substance to seriously affect the heat test. This “masking” of the test, as it is called, is obviously a serious matter, as it prevents the true character of the explosive from being ascertained. As soon as these disclosures in England became known various brands of explosives im])orted into this State were critically examined, and in three instances mercury was discovered. The result was that three prosecutions were instituted and very serious fines were inflicted. Such drastic steps have been taken in connection with the matter that the practice has probably been entirely stamped out.

Physical Examination. — Not less inqiortant than the chemical examination above referred to is the physical examination, which should be part of every scrutiny of a stock of explosives. The principal points of this examination are; —

1. For Exudation. — If the explosive has been subjected to rapid changes and extremes of temperature; for instance, if it has been in a magazine which readily becomes heated by mid-day temperatures and as rapidly falls to low temperature at night, it will very often show the harmful effects of these conditions by exuding nitro-glycerine. This has already been particularly referred to, and need not be dwelt n]mn further here, except to say that the oily layer of nitro-glycerine formed either in one part or all over the cartridge by continued exudation is a great source of danger in blasting. The friction liable to occur when the cartridge is being rammed into a bore-hole would be very apt to give rise to premature explosion, owing to the

is for ordinarv gelatine coiupouiKls. Dynamite ami exjilosives of a ‘lifferent character are tested by special modification of the procedure above described. Devised bv Dr. Dupre and first introduced by the Home Office Inspectors.

Expi.Ostvks

extremely sensitive character of nitro-glycerine. In the case of ordinary dynamite (Dynamite No. 1 or red dynamite), this exudation is also caused merely hy contact with water, hut with the gelatine compounds (blasting gelatine, gelatine dynamite, and gelignite) water does not have this effect, and it is more important that they should he kept at an equable temperature, though the atmosphere should be as free from moisture as possilhe; hence the prolonged storage below ground in mine magazines is to be avoided.

2. For Freezing. — Nitro-glyceriiie freezes at 47 degrees Fahr., so that at

comparatively high temperatures all the nitro-glycerine compounds rapidly assume a frozen condition, the cartridges becoming hard, stiff and inelastic. When in this condition they are more inert, and not so likely to give rise to a complete explosion, while the danger that accompanies the thawing of frozen explosives is testified to by the numerous reports of disasters which are on record. Such explosives should always be thawed by being placed in a tin or canister, which is then placed in another receptacle containing hot water.

3. For effects due to conditions of storage. — It is found with explosives

that have been stored in a moist magazine, or that have become wet and afterwards dry again, that the cartridges are frequently covered with a fine salty powder; this is saltpetre, which has been extracted by the moisture from the explosive, and which has crystallised on the wrappers as the moisture has evajiorated. Such explosives should not be used, as the uniform intermingling of the constituents has been interfered with, and such an explosive would be liable, therefore, to give rise to noxious fumes, owing to incomplete or irregular explosion.

The tests, therefore, that are applied to explosives may be summarised as follow: —

1. For uniformity and correctness of composition.

2. For freedom from acid.

3. For freedom from exudation, and other physical defects due either

to defective manufacture, unfavourable conditions of storage, or accidental damage.

The preservation of a high degree of quality in these respects depends chiefly upon the manner in which an explosive is stored. It should never be kept in a hot moist atmosphere such as would be found in the closed workings of a mine ; a magazine should always be thoroughly well ventilated, and should not be subject to large or frequent fluctuations of temperature. Considera1)le experience has now been gained with the class of magazines that are generally employed in this State, and they have been found very satisfactory. Their structure is very light (this being desirable in order that there should be no projection of heavy debris in case of an explosion), and consists entirely of wood and galvanised iron. The special feature, however, is the construction of the walls which are built in two and sometimes three compartments in such a manner as to afford ample ventilation to the interior of the

West Australian Mining Practice

bnilding aud yet, at the same time, to provide a jacket of air insulatiou all round the building. A very extensive series of records with maximum and minimum thermo meters has been taken in buildings of this character liotli at Eremantle and Kal- goorlie, extending in some cases over two or three years, and the result may be summarised by saying that the maximum temperature recorded in the most poorly constructed of the buildings was about 94 degrees Fahr., and that the tem perature of the magazine was in all cases lower than the maximum outside temperature and higher than the minimum outside temperature, that is to say that the building was slow in heating and equally slow in cooling. This is just what is required so that the fluctuations of temperature in the building are both less rapid and smaller in extent than those of the ordinary air temperature. The ideal maga zine would be that which retained the same temperature all the year round and the best construction is that which approaches most nearly to this ideal. There are throughout this State something like 100 magazines which are supervised by Government officials to see that their structure is imoperly maintained and that the stocks contained in them do not, with lapse of time, deteriorate beyond the desir able limit.

As soon as a shipment of explosives arrives in Eremantle, s}jecial officers visit the ship while the cargo is being discharged into the lighters and they thoroughly inspect the cargo. Two per cent, of the cases in the shipment are opened, and samples taken, so that from a shqDment containing 50 tons of explosives (that is 2,000 cases) 40 samples would in the first instance be taken. If the first tests are unsatisfactory, a larger number of additional samples are taken until the nature of the entire shipment has been ascertained. The lighters, as soon as they have taken on their cargo, are removed to the explosive depot, ahout five miles from Fremantle, where they remain until the samples have been thoroughly tested. When these samples have been passed, the explosives are landed and distributed either into the larger magazine depot at Fremantle or by rail to the goldfields. The depot at Fre mantle is almost unique in its character, comprising over 320 acres, and contain ing 20 large magazines and 7 detonator magazines, with a total storage capacity of 600 to 700 tons of explosives. A special landing jetty and sorting shed with railway connection to every magazine and to the general railway system enables the safe handling of large quantities of explosives with a rai)idity probably not exceeded in any part of the world. Here the explosives are under control and special super vision during their storage, so that no explosive is allowed to go from the coast to the goldfields which has not satisfactorily passed a qualifying examination. As already explained, however, the lapse of time brings with it the necessity for repeated examination of the stocks on the goldfields and continual vigilance to ensure a high degree of quality being maintained. In Kalgoorlie (which is the largest mining centre) there is another large depot with an area of 150 acres and containing 13 magazines, having an aggregate capacity of 250 tons. This, however, is to be replaced by one larger and better equipped.

The treatment of this subject would not be complete without a reference to detonators and fuses. The object of detonators is to create an enormous initial impact, which shall set up within the explosive charge what is known as an “explosive wave.” This is known as detonation, and is quite distinct in its character and result from

b]XPLr)SIVP:]8

combustiou. Without going into abstract technical details it may be said that the I'uines caused by setting lire to a quantity of gelignite are quite different from those produced by explosion. This is well-known to the miner, who si)eaks of a hole as having “burnt” when he smells certain fumes in the atmosphere. The cause of this so-called burning is sometimes obscure. It is doubtful whether the explosive frequently, if ever, actually catches fire in the hole, and it is very probable that the formation of these fumes is due to the initial impact of the detonator being insufficient to peiietrate to the extreme limits of the charge. The subject is one which is obviously difficult to investigate experimentally and the explanation given must be considered as only hypothetical. The matter may be more easily explained by taking as an instance three plugs of blasting gelatine in a hole fired by a Xo. 3 detonator. The detonator will undoulffedly cause sufficient impulse to explode the first plug in the charge. The explosion of this will be communicated to the second, and thence to the third, and the whole charge will apjjarently explode, yet amongst the resnltant gases there may, in some cases, be detected fumes such as are caused when an explosive burns. Even if this does not happen with only three cartridges in the charge, it may happen if they are six or eight deep, or even more. If instead, however, of a Xo. 3 detonator, a Xo. 6, 7 or 8 were used, the initial impulse Avould be transmitted right to the extreme end of the charge, instead of being passed on from cartridge to cartridge, and no fumes would be observable after the blast. While the explosion has to be passed on from cartridge to cartridge it is x>ossible that towards the end of the charge the inii)ulse is so diminished in force as not to create that instantaneous transformation of the explosive which is necessary for the best result. “Detonation” in such a case ax:)X5roaches the nature of “combustion.” This view is borne out by the fact that in general, when many complaints of fumes arise, there are, simultaneously, rex)orts of “butts” being left unexjloded in the holes, and of unexploded xfiugs being found in the broken ground by the shovellers. If this hypothesis, which seems concordant with exxerience, be correct, it is of the highest inixortance to use only the strongest detonators, and this X)articularly with the less raxjid exx:losives, gelignite and gelatine djmamite. In Western Australia it has become the almost universal x'>i’actice to use No. 6 or Xo. 7 detonators, and the use of Xo. 8 is becoming more widesxn-ead every day. There is no donbt that the extra exx'ense is amply rexaid. It is not generally recognised that if the fulminate of mercury, which is the explosive contained in a detonator cax>, becomes damp or is even exxmsed to a moist atmosxjhere, it is liable to become diminished in Xower (wet fulminate of mercury is quite safe to work with) so that these are the two most important things to be remembered in connection with detonators. First, to “keex your x)owder dry”; second, not to be sparing as to the strength of detonator emxfioyed. It is well for those having much to do with the xurchase of exxfiosives to remember that in many cases it has been xroved that the nominal strength of a detonator is not rigidly adhered to in manufacture. Some information on this point will be found in the rexort of the Western Australian Commission on the Ventilation and Sanitation of ilines, and it is well, therefore, to use only those detonators of such manufacture as has been found by practical exxerience to be thoroughly trustworthy. Some manufacturers again use mixtures of various substances instead of xnre fulmin ate of mercury, and there is great care necessary to ensure that ouly thoroughly re liable cax:s are used.

West Australian Mining Practice

Safety Fuse. — Great attention has been attracted during the last year or two on onr goldfields to the question of safety fuse. Prom time to time accidents have occurred, the responsibility for which has been thrown upon the fuse employed. Some of these cases have not borne investigation, and in otliers, where some doubt does appear to have rested upon the fuse, the results seem to have been inevitable. It is obvious that though numbers of samples may be taken annually for inspection purposes, yet in all only a small proportion of the coils used can really be examined. In the course of mining operations eventually every foot of this fuse is burnt through, and if there be only one faulty length in the whole annual importation it must be dis closed to the miner, perhaps with disastrous results, while the chance would be some thing like half a million to one that it would be encountered amongst the samples drawn for test.

The definition of safety fuse in the Regulations is as follows: —

Safety Fuse, consisting of a fuse for blasting, which burns and does not explode, and which does not contain its own means of ignition, and which is of such strength and construction, and contains an explosive in such quantity that the burning of such fuse will not communicate laterally with other like fuses.

As far as the Explosives Act is concerned it has no further interest in the fuse than to see that it complies with this standard, but under the Mines Regulation Act a regulation has been made requiring fuse for use in mining to have a certain burning- rate — namely, not less than 80 seconds, or more than 100 seconds per yard. In one year, of 929 samples of fuse tested only two went over and only 31 went under the prescribed limits. From time to time in connection with accidents on the goldfields, it has been alleged that samples of fuse have “run through,” causing premature explosion, but there is widespread evidence of an overwhelming character to show that the safety fuse used here never runs through when burnt. A sample might occasionally explode or misfire but any report which describes the “running through” of an ordinary safety fuse is always to be discredited. It has been suggested that it might be possible that “short circuiting” occurred, due to the method of handling the fuse in our mines. When a miner fires a “round” of holes it is customary for him to tightly double up the length of fuse protruding from the holes and force it, in a crushed condition, into the mouth of the bore-hole, this being done to prevent the fuse being cut by flying stones, etc., from the earlier holes in the “round.” This treatment, might, by injuring the wrapper of the fuse and putting it in a state of strain, cause the flame (when such a fuse was ignited in its turn) to communicate from one bend of the fuse to another at a point much closer to the charge, thus causing the latter to ex plode very much sooner than was expected, and giving rise to the idea that the fuse had “run.” In order to test this a series of experiments have been carried out in which galvanised iron tubes were employed of Iks in- internal diameter (the size of the ordinary machine hole on our mines), and about 12 in. long, and length of fuse 6 ft. long (about the average length of the miner’s “stick”) were coiled or bent and tightly crushed into these tubes. They were then burned alongside of lengths of the same fuse laid out on the ground in the ordinary way. The results were very striking. Out of 287 tests no increase of speed was manifested by the samples in the tubes, and in fact, as a general rule, by this treatment the rate of burning was re-

Explosives

tarded, in some cases, to a considerable extent. Of tlie total number of 287 fuses tested in tubes, 107 showed a retardation as compared wdtli fuses burnt in the open, while only tivo showed an acceleration of speed, and this very slight. While this method of treatment, therefore, has no effect in accelerating the burning rate of the fuse, and the tests still further emphasise the improbability of any of our safety fuse “running through” during use, it is of some importance to note that a certain retardation of explosion may be caused by this douliling of the fuse, and this gives an additional reason for discouraging the tendency, which often exists, for men to re turn too quickly to holes which they suspect liave missed fire.

Summed up, the result of the most careful investigation seems to be that the greater part of the fuse used in this State is of a very uniform character, and that there is no evidence to support statements which have been made to the contrary, from time to time. Stress has already been laid upon the unavoidable disadvantage of testing by sample. An inspecting otficer may not get a bad piece, which the miner is bound to encounter sooner or later, and on the other hand if an inspector out of a liundred samples encounters only one which is faulty, there seems hardly sufficient justification to condemn the whole shipment, for the chances are against the occurr ence of another sample of that kind. The prescribing of certain time limits for fuse in this State was a very radical advance, which called forth a good deal of criticism. <'V It was said that the manufacturers could not conform to this standard owing to the difficulties in the process of manufacture, but this regulation was justified by the circumstances which gave rise to it, and still further by the results which have followed its adoption. The burning rate of the fuse has now become a matter of special interest to the miner, and all-important as it is for both his personal safety and for the efficiency of his work, it is surj)rising that it should for so long have remained a matter of indifference. Every mine keeps a most careful check on the burning rate of its supplies of fuse. In most mines samples are tested from every cask before being used and the results are posted for the information of the workmen.

Fumes from Explosives. — Wherever ex])losives are used throughout the world attention is drawn to the gases arising from their explosion. Some few years ago numerous complaints arose as to the formation of noxious fumes in the West Austra lian mines. These owed their origin to a number of more or less serious cases of “gassing” which had occurred, and in consequence, when in 1900 a Eoyal Commis sion was appointed to enquire into the Ventilation and Sanitation of Mines, one of the most important questions submitted for their consideration was that of the pre sence in our mines of deleterious gases due to the explosives used. The complaints were, in some instances, specially levelled against particular brands of explosives, and a great deal of conflicting evidence was given l)y witnesses. So much so that the Commission found it necessary to themselves carry out extensive experiments in order to conduct an independent enquiry into the subject. The Commission’s Report is ]mblic property and that portion dealing with their investigations on this subject has been issued as a separate bulletin l)y the Mines Department. It is not necessary again to go over the entire ground traversed by that Commission, but one or two important points call for special attention.

(a) Western Australia was apparently the first country to impose such a restriction. (b) Bulletin No. i. — Explosives and Analytical Department.

West Australian Mining Practice

Of the gases which might be formed by an explosive there are three which must be accounted deleterious, viz., Carbonic Acid (CO), Carbonic Oxide (CO), and Nitrogen Peroxide. Carbonic Acid or Carbon Dioxide is the ordinary choke damp so well-known amongst miners all over the world. Its effect is to cause insensibility and suffocation by the exclusion of oxygen from the body. It declares its presence when in large quantities by reducing or extinguishing the ffame of a candle. On account of this property the custom of testing the purity of air in workings by means of a candle lias come to be considered as a conclusive test — but this is fallacious. If in any working place a candle is exting iiislied it is certainly to be considered dangerous but the reverse is not always true. Carbonic Oxide or Carbonic Monoxide does not affect the candle ffame even when present in quantities highly dangerous to life, and indeed it cannot be readily detected by the miner by any simple test. It is a very dangerous gas affecting the blood and giving rise to cumulative effects which may not give any preliminary symptom of their existence. A man may be working in apparently good air with his candle burning brightly, and only after the lapse of some time he is suddenly overcome and falls insensible. While a very considerable proportion of choke damp in the air is required to affect a workman seriously (7 to 8 per cent.) very small cpiantities of the Monoxide (0.25 per cent.) are sufficient to be dangerous. Nitrogen Peroxide (which if formed is undoubtedly accompanied by other nitrogen oxides) generally declares its presence by its irritating effect upon the throat and eyes, it is probably only formed under abnormal conditions. The choke damp is generally not produced in quantities which present a serious danger under the work ing conditions that exist, and the most urgent question therefore to be solved is whether the second — Carbon Monoxide — is formed under ordinary conditions, and if so, in what quantities. In order to understand the reasons for the production of this gas it is necessary to explain some of the elementary principles applied to the building up of an explosive.

A modern high explosive consists of a mixture of complex compounds (Nitro-glycerine, Cellulose, Nitro-cotton, Saltpetre), the active portions of which are composed of Carbon, Hydrogen, Oxygen, and Nitrogen. When an explosion occurs these various elements are re-arranged into simpler componnds, the tendency being towards a complete oxidisation of the combustible elements (carbon and hydrogen) Iiy the oxygen giving rise to the formation of carbon dioxide (COg) and water (HgO). Theoretically this complete oxidation should always take place, provided —

(a.) That the initial detonating impulse is sufficient to produce the re quired physico-chemical conditions.

(b.) That the proportions of combustibles and oxidiser are so “balanced” in the composition as to provide an excess of the latter.

If either of these conditions were unfullilled we should ex])ect to find — instead of carbonic acid and water vapour (the products of complete oxidation) — a propor tion of insufficiently burnt carbon giving rise to the highly dangerous carlionic oxide (CO).

ffdie Commission before referred to came to the conclusions that (1) our ex plosives were ])roi)erly “lialanced” in their conqiosition and (2) that practical tests failed to disclose the presence of CO — and that the latter could only be formed under

Explosives

2P.)

abnormal conditions. These conclnsions were in contradiction of tlie opinions held by weighty authorities hO who liad l)een investigating the same cpiestion in South Africa, hnt no fnrtlier advance was made until Drs. IMoir and AVeiskopf and Air. AV. Cullen published the result of further experiments in the 'Jh-ansvaal. These experi ments, which haA"e l)een most alhy i)lanned and skilfully carried out go to show that CO is formed in all cases, even under the normal contlitions of blasting. This very serious conclusion, if fully confirmed h}" further investigations, will represent one of the most iin|)ortaut steps which have been taken in recent years in connection with the scientific investigation of industrial ex])losives — and a further series or similar exi)eriinents under AAestern Australian conditions has been undertaken. Unfortunately details have not been given as to the exact composition of the explo sives emi:)loyed, so that though it is hardly conceivable that the explosives used in South Africa are wrongly compounded, we yet require proofs that these results can be obtained with a properly “balanced” explosive. It has been advanced as one possible explanation of the presence of CO that the carbon contained in the paper wrappers is sufficient to destroy the balance of the explosive and prevents the complete combustion which would otherwise result. It has also been suggested that CO is derived from the powder core of the fuse employed. An examination of all the brands being used in AAestern Australia was recently made to investigate this question of “balancing” and it may be of interest to show the result as indicating also the method of inquiry followed in such a case. The various ex])losives were first analysed to find the proportions of their ingredients and from this their contained hydrogen, carlmn, oxygen, etc., were worked out in the following manner: —

Brand.

Explosive.

Composition.

Per Cent.

Carbon.

Containing

Hydrogen.

Oxygen.

Nitrogen.

A

Gelignite

Nitro-Glycerine C H (NO

3 5 3 -*3

61'44

Cellulose (Wood Meal) C H O

—

Nitro-Cotton C H (NO.OH) O

24 22 “ 9 11

Potassium Nitrate KNO

—

Calcium Carbonate CaCO

—

—

—

Totals

Oxygen required for complete combustion of Carbon ,, ,, ,, ,, of Hydrogen

Balance — Excess of Oxygen

5.51 per cent.

(aj Drs. Moir and -VVeiskopf, South Africa Miners' Phthisis Commission 1902-3.

Table Giving Composition of the Various Brands of Nitro-Glycerine Compounds Used in Western Australia so as to Disclose the “Oxygen Balance” of their Constituents.

West Aestraivian Mining Practice

The following .Viistralia : —

table gives the results for all the brands used in Western

O

4 O

o

U

Oxygen

ciency-

d-

b

ro

b

Oxygen

Excess-

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b

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b

b

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r>.

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O

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£

d

Q

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d

Q

S

d

Q

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d

P

Q

e

d

Q

0)

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biO

bc

0)

bjO

bi)

0)

biO

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.£

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'c

'c

.£

bc

b£

d

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bc

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(/)

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d

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Q

JlXPLUSIVES

'lliis table shows that nearly every explosive used iii Westei'ii Australia has its constituents so “balanced” as to provide an excess of oxyg'en over and al)Ove that ]-e(iuired for com])]ete burning of the “combustible” constituents and that therefore there should (theoretically) be no noxious Carbonic Oxide formed. (“) The one or two exceptions (all Blasting Gelatines) exhibit so slight a deficiency of oxygen that it cannot l)e considered as serious. It is renuu kable also that complaints of fumes seldom arise where blasting gelatine is used, ft is still ])ossil)le that some of the ingredients (e.g., wood meal) from their nature cannot be so thoroughly incorporated in such a substance as gelignite as to bring about com])lete combustion, even though there is suflicient oxygen to do so and that they are therefore only partly burnt. Such ({uestions as this oi)en a great field for reflection and indicate directions in which the immense ])rogress made in the manufacture of these explosives may be still further advance<l. What has been said, however, will indicate the care and thoroughness with which such questions require to he investigated by those engaged in the direc tion of mining operations, and it must l)e said that the mine manager is as a rule quick to appreciate the importance of such investigations.

1. Efficient work, as well as humanitarian considerations demand the

most sanitary conditions of labour. Good ventilation and ])ure air lengthen the life of the workers and increase their efficiency.

2. The responsibilities thrown upon employers by the Employers’ Liability

Act require a close study of such a technical subject as this in order that advantage may be taken of the latest knowledge available. If a workman is seriously injured through gassing, scientific facts dis closed by such investigations as have been described may have an important bearing on the question of responsibility.

3. If the explosives are not being completely detonated they are not do

ing the maximum work possible, and this has its effect upon the costs sheet.

It is accey3ted as a truism throughout our goldfields that “overcharging of holes” is the rule, i.e., that more ex]3losives are used than are actually required to lift the “burden” to be moved. This is said to be necesary as a precautionary measure to make sure of the “shot” and prevent the necessity of retiring. Such a ]3ractice is objectionable as tending to unduly increase the vitiation of the air by fumes and also as leading to waste of explosive.

The table given on page 210 sets forth the enormous temperatures and pressures which are produced by a high explosive “when detonated in its own volume,” he., yiractically equivalent to the condition of a charge lightly rammed into a well stemmed bore-hole. It is evident that there is here a set of thermo-dynamic changes which are largely interdependent. The high temperature obtained is dependent upon the maintenance of the enormous pressure and the pressure is caused through the expansion of gas due to the tenpierature. One might say, therefore, that it is necessary that the containing envelope (in mining, the rock surrounding the bore hole) should not have its resistance broken down before these interde]3endent thermo-dynamic factors have reached their maximum. If it should lu’eak much be fore this point is reached the full physical changes and the resulting chemical pro-

(a) Investigations both here and in South Africa show that the nitrogen is not oxidised.

t22-2 AVRS'r AUSTRALIAN MINING PRACTICE

(Inets (‘aiiiiot Le coiu]:)letely attained. Tn other Avords the more nearly the ])urden is exactly adjusted to tlie charg'e tlie more complete shonld l)e the ex]Alosion — the better shonld he the return ot‘ work obtained from the explosive and the less shonld 1)e the fames.

hdie ta])]e referred to gives results obtained by exploding charges in a bomb calorimeter and which approach closely to the theoretical. (It will be seen from the composition of the gases that the combnstion is coupdete.) Such results are generally obtained in calorimeter experiments, for ol)vionsly the envelope is made strong enough to resist all possilhlity of rnptnre and the Amry best conditions are there fore obtained. In practical mining, however, neither the theoretical conditions nor effects are obtainable and hence the occurrence of “fumes,” “incomplete detonation,” “nnexploded butts” and “overcharging” which are all probably more or less connected. It is a fact of common experience that Avhere conpdaints of “fumes” arise there are generally simnltaneous conpffaints of nnexploded “butts” being left at the bottom of bore-holes or nnexploded cartridges l)eing found amongst the I)roken rock thrown out by a “shot.” This last indeed has l)een a Amry prolific source of trouble on onr fields. These nnexploded cartridges i)assing with the ore into the Griffin Mills and other crushing plant, have caused by their explosion there, so much damage that regular means are now employed for special oversight of the ore passing to the crushers so as to liaA-e them picked out by hand.() It has repeatedly been found that when this trouble has become excesslAm a determined effort to generally reduce the size of charges employed has led to a diminution of the trouble and to a simultaneous reduction of fumes.

Special attention has been called in South Africa to the economy which can be effected by a more carefully planned arrangement of holes taking advantage of natural “fissures” and “lines of weakness” in the rock blasted. This, which is simply a special phase of the question of adjustment of charge to burden, is a matter which might well repay careful consideration. Electric firing has been sometimes suggested as one means of reducing some of the troubles referred to, e.g., one common cause of fumes is the necessity for repeated firings of the “cut” in a face — it is urged that this could generally be aAmided by using electricity for cut firing. This system of firing was experimented with on the Western Australian goldfields some ten years ago but was entirely abandoned.

The principal objections to its use were —

{a.) SeAmre destruction of cable with the heavy blasts employed.

(5.) Difficnlties in preserving insulation and ensuring reliable connections.

AVhether these objections will ultimately be satisfactorily overcome it is diffi cult to say, but for the present at least the concensus of o]Ainion amongst mining ]uen in Western Australia is opposed to the use of electric firing.

In conclusion it may be of interest to show the amounts of explosiAms which are annually imported into this State and a comparison with onr Eastern neighbours. AAhien the enormous quantity of explosives shown in the following tables is considered together with the wide distribution OAmr large areas of this State, it is a matter for congratulation that so few accidents haAm been recorded. Apart from the accidents on

(a) Tt has been proposed bv some of ojir mine managers that the explosives shonld be wrapped in special highly coloured wrappers to facilitate their detection in this way, but so far, for some reason, the suggestion has not been generally adopted.

Explosives

mines, Avliich cannot he considered to constitute a t’orniidahle list, there have, during the last 13 years, ))een only tAA'o serious accidents in this State -namely, tlie explosion of a detonator magazine at Fremantle, and of a dynamite magazine at Coolgardie, both of Avliich — there seems little room to doubt — Avere the result of deliberate human agency. This may he taken as an indication of the exceedingly high quality of the explosives generally used in this State and of the care and skill A\dth Avhicli the aver age mining engineer avails himself of their poAverfnl aid.

Statistics Of Importations Of Explosr'Es Into M'Estern Australia.

Table L- Importation for 1909.

Explosives.

Quantity.

Lb.

Value.

£

Gelignite

2,378,100

87,167

Dynamite

7,500

Blasting Gelatine

370,500

20,039

Gelatine Dynamite

310,250

14,300

Detonators (number)

3,210,144

4,804

Fuse (coils)

498,900

10,920

Powder, Blasting

242,217

6,163

Powder, Sporting

Explosives, N.E.I. Ar)

—

9,936

Fireworks

/154,086

{a) Not elsewhere included.

Table IT— COxMparison of Importations for the Last Six Years.

Explosives. &c.

1907,

£

£

£

£

£

£

Nitro-Glycerine Compounds

158,472

157,467

103,062

124,354

121,813

Blasting Powder

3,352

5,026

2,317

5,403

2,896

6,163

Sporting Powder

Fuse

15,653

14,762

10,893

8,476

11,265

10,920

Fireworks

Cartridges ...

14,781

11,061

15,099

9,924

Detonators ...

4,043

3,322

3,935

3,341

4,804

N.E.I.

2,641

12,725

1 ,066

Caps

A199,565

Also, 998

Al99,253

Al22,592

A157,426

A154,086

West Australian Mining Practice

Table III. — Kinds and Quantities of Principal Industrial Explosives

Imported in 1908 and 1909.

Explosives, etc

lb.

lb.

Gelignite

3,261,928

2,378,100

Blasting Gelatine

438,500

370,500

Gelatine Dynamite

339,852

310,250

Dynamite

12,000

7,500

Blasting Powder

116,500

242,217

Sporting Powder

1,150

4,169,930

3,309,142

Table IV. — Comparison with Other States.

Explosives, etc.

Western

Australia.

New South Wales.

Queensland.

Victoria.

South

Australia.

Tasmania.

Proportion of Total for Australia imported into W.A.

Nitro-Glycerine Compounds

Lb.

3,066,350

Lb.

1,325,145

Lb.

1,531.280

1,753,140

Lb.

554,400

Lb.

434,400

Blasting Powder ...

242,217

1,851 ,900

709,100

234,000

123,250

44,875

Sporting Powder ...

26,140

3,750

83,000

9,150

2,150

3,309,142

3,203,185

2,244,130

2,070,140

686,800

481,425

27.58 %

Fuse

£

10,920

£

£

10,397

2,256

2,532

Detonators

4,804

6,330

4,282

4,506

1,335

Explosiv'es N.E.I. ...

17,641

4,217

6,004

3,875

/15,731

423,971

418,896

412,766

44,099

45,210

19.49 %

Total Value of Explosives enumerated above

/

143,772

k

86,609

99,204

96,835

33,646

28,567

29.42 °/o

It is not clear from the return whether the Victorian importations include also those shown for Tasmania, This may probably be so, since the Tasmanian importations are, it is believed, tested in Victoria. This would modify the figures in the last column considerably.

West Australian Ailning Practice

Chapter Xv

Ventilation Anh Sanitation

VEN'ITIjATION. — Artificial means of \'eiitilation underground has not yet been found necessary, and down to depths of between 2,000 and 3,000 feet natural ventilation and the use of compressed air furnish good su])])lies. In addition to the shafts, the various levels are connected with the surface hy rises, and good currents of air are ])rocured. In some instances the third compartment of a shaft is close-lined right up to the crown of the head-frame, thus constituting a good upcast shaft. On the levels, air-doors are in use to some extent to divert currents through stopes and similar workings. Hot ends are ventilated usually hy blowing off com pressed air while men are engaged at work, or by using galvanised iron pipes, the current in which is induced l)y an air-jet set in the piie at about fifty feet from the intake. These pipes are conducted from the nearest air-pass to the working face.

Where possible, connections at convenient levels have been made with neigh bouring mines, or with abandoned workings. If, however, work is being carried on in the mine in which connection has been made, the result is not satisfactory, as one mine gets the whole of the smoke and hot air of the other when firing is in progress.

Sanitation. — At all the mines great attention is paid to the sanitary condi tions al)Ove and below ground. On the surface very complete change-rooms are provided. These are of one or two storeys in height and of dimensions varying with the number of men to be ])rovided for. Every man is required to bring a change of clean clothes at the beginning of each week, and to remove his working change for washing. On coming on shift the worker undresses in the first room and passes on to the second room to assume his working clothes. On leaving his work the process is, of course, reversed, and the worker has access to a bathroom in which hot and cold water is provided without stint. When the off-shift has passed out, the room attendants fasten the working clothes to hooks and hoist them overhead, Avhere they come in contact with hot air from steam pipes and are dried. Each man has his place and number in the change-room. If a worker leaves clothes in the change-room at the end of the week they are liable to be taken out and burned by the attendants. Bundles of clothes are subject to examination before being remoAmd from the rooms. Tea cans have to be uncovered and inAmrted on pegs or, in some instances, a duplicate can is imovided by the management; in this case the can that is used underground has to he left in the working-clothes room, and it is cleaned by the attendants. As souii as change of shift has been effected the rooins are cleaned and the walls and floors hosed with Avater. The system of complete change of clothes is compulsory. Drinking AAmter is provided

West Australian Mining Practice

at each level. In some mines it is let down in pipes to small cisterns closely covered and provided with tap and drinking cup. In others closely-covered cans are used; these are filled on the surface as required, and the cans are kept clean.

Underground, on each level, sanitary pans are placed at suitable spots behind screens, and deodorisers mixed with sawdust are used. The pans are changed at periods ranging from once a day to twice or three times per week, according to the number of men employed. After being sent to the surface the pans are removed by contractors controlled by Boards of Health for the various districts. On each leve], places are set apart in which men can sit and eat their crib or lunch. A water tight waste box is provided, into which waste papers, remnants of food, and other debris have to be thrown. These boxes are sent to the surface at regular intervals and the contents burned. In each mine men are detailed to see that every sanitary appliance is kept clean and free from rubbish. The introduction of this system has been of great advantage to all men employed underground. If any of the employees are neglectful in the use of the conveniences provided, they are liable to dismissal.

Every employee oii a mine is entitled by custom to draw a certain daily allowance of water from the mine-owners in addition to what he may consume during the hours of work. For single men the allowance is at the rate of two gallons per day, and for married men four gallons ])er day. In districts where fresh water is not available the salt mine-water is condensed and becomes the sole source of water for domestic use. In a few districts Avells of fresh water exist, but these are not common.

West Australian Mining Practice

Chapter Xvt

Water Supply

Description of Government Water Supply — Pipe Line — I’niiiping Mncliinery — Eeservoirs and Eeticulation — Cost.

NO reference to the mining industry of AVestern Australia would be complete without mention of the great engineering enterprise that conceived and suc cessfully carried out the existing service for the supply of fresh water to the mines and communities on the Eastern Goldfields of the State. Of its kind it is perhaps one of the most unique pieces of hydraulic engineering work in the world, and it is noteworthy that, unlike most other systems of water supply, the huge scheme was undertaken at a cost of nearly £3,000,000 sterling, not primarily to ensure the subsistence of a large community of people, but to maintain, encour age, and develop a staple industry established in a practically waterless district some 400 miles from the AAestern coast of the State.

Air. C. S. R. Palmer (the late Engineer-in-Chief of AAestern Australia) read a very interesting paper on the Goldfields AA'ater Supply before The Institution of Civil Engineers, on Alarcli 28, 1905, and with the consent of the author, and through the courtesy of the Institution, the following extracts from the pai)er are now published. The blocks and plates are also reproduced, by permission, from the transactions of The Institution of Civil Engineers.

General Outlines of Scheme. — A daily supply of 5,600,000 gallons was pro vided for, of which 5,000,000 gallons was for use in the Goldfields, and the balance for waste and consumption en route. The supply is obtained from an artificial reservoir, having a capacity of 4,600 million gallons. From this reservoir the water is pumped through a steel conduit, 30 inch(!S in diameter, by a series of eight pumping installations, to the main distributing-reservoir at Bulla Bulling, 308 miles from the main-storage reservoir and 1,290 feet above the lowest outlet-level of the latter. From the Bulla Bulling distributing-reservoir the water gravitates for 21 miles to the Coolgardie service-reservoir, and thence to the Kalgoorlie service- reservoir, a further 23% miles, the total length of the conduit from the supply- reservoir being 351% miles (Fig. 8, Plate XIII).

The first pumping-station is located on the right l)ank of the blelena River and 650 feet down -stream of the storage reservoir. The pumps draw their water from a stand-pipe 4 feet in diameter, which is placed immediately in front of them and is fed by a 30-inch steel main, which, beginning at the outer valve-house.

Paper No. 3516, "Coolgardie Water Supply." By Charles Stuart Russell Palmer, M. Inst., C.E. Minutes of the Proceedings of the Institution of Civil Engineers . Vol.CLXII. Session 1904-1903. Part IV .

Wp]St Ausjralian Mining Practice

passes mider tlie Jioiler-liouse l)efore entering' the stand-pipe. The ])nnips here lift tlie water a net lieigdit of 415 feet, through llh mile of ])ipe, and deliver it into a coiicrete receiving-tank, having a capacity of 4()8,000 gallons and a depth of 15 feet of water. The pumps at Station No. 2 draw tlieir water from tins receiving-tank, the maximum suction-lift being liy2 feet, and deliver it into a concrete regulating tank at P)aker’s Hill, 2214 miles from Station No. 2, the net lift being 340 feet. From the Baker’s Hill regulating-tank, which is 15 feet dee}) and has a ca})acity of 500,000 gallons, the water gravitates to the West Noi'tham regulating-tank, 12 miles distant, ’khis tank is similar in construction to that at Baker’s Hill, having the same cai)acity and de}ith. The net fall is 94 feet from Baker’s Hill to West Northam, whence the water gravitates to the Chmderdin reservoir, a further 41 miles, thus making a total length of 75% miles between Stations 2 and 3. The Cunderdin reservoir has an available ca})acity of 10 million gallons. No. 3 })uni])ing-station is located al)out ‘Ya mile from tiiis reservoir, and the ])umps draw their water from a stand-})i]:)e, similarly to those at No. 1. The section hetween Stations Nos. 3 and 4 is (i2'14 miles in length, the net lift at No. 3 being 215 feet. The water is delivered into a circular concrete tank at No. 4, having a capacity of 1 million gallons and a dei)th of 15 feet. From Station No. 4 the water is lifted a net height of 333 feet, and delivered through a section 321/2 miles long into a rectangular concrete receiv ing-tank 20 feet deeip with a capacity of 1 million gallons. .Vt Stations Nos. 5, 6, 7, and 8, the arrangements are similar to those at Station No. 4, and the receiving- tanks at Nos. 6, 7, and 8 are similar in design to that of No. 5, having also the same cajiacity and depth. The net lifts at Stations Nos. 5, 6, 7, and 8 are respectively 52 feet, 100 feet, 56 feet, and 183 feet, and the corresi)onding lengths of section 46 miles, dl'Yi miles, 45 miles, and 12% miles. From Station No. 8 the water is delivered into a main service-reservoir at Bulla Bulling, of 12 million gallons capacity. Thence the water gravitates to Coolgardie, and from Coolgardie to Kalgoorlie. These towns are lu'ovided with circular concrete service-reservoirs, that at Coolgardie having a ca]acity of 1 million gallons and that at Kalgoorlie of 2 million gallons.

Discharge of Helena River at Weir Site.

Mean Rainfall Mundaring and York.

Discharge.

Ratio of Discharge to Rainfall.

Year.

Indies.

Million Gallons.

Per Cent.

24'5

30'76

3,802

37'17

1,857

9,622

1,401

Not only are these ligiires very Ioav, but the ratio of the discharge to the rainfall varies cousidei'abl>' more than does the rainfall. The small results as a whole can be accounted for partly by the :ibsoi'])tive nature of the soil of much of

Water Supply

llie catcliiiieiit-area, tlierein dilTeiing from tlie catclimeiit-areas usually available in other counti'ies, and partly by the fact that tiie rain is })recipitated very unfavour ably; for although the annual fall, iji the vicinity of the reservoir, for instance, aver ages about 37 inches, it is spread over a })eriod extending from about May to Novem ber, inclusive. During some mouths it rains nearly every day, but only on very rare occasions does the fall exceed 1 inch in 24 hours, the average being less than i/4 inch, generally in light intermittent shoumrs. The result is that the main water courses do not l)egin to how until 10 to 12 inches of ]-ain have fallen, and they stop almost immediately the rainy season ends. The rainfall for the year 1902 may be taken as typical of the rainfall generally. During that year the total rainfall, as recorded at the Helena weir, amounted to 27 'h inches, the total number of rainy days being 81; i.e., the average precipitation i)er rainy day was only 0.34 inch. The maximum rainfall in any one day was 1.41 inch.

Construction of the Weir. — The weir was built to the section shown in Fig. 9, Plate XIII, the governing factors of the design 1)eing that the maximum pressure on any portion of the walls should not exceed 8 tons per square foot, and that the centres of pressure should be Avell within the middle third, both with the reservoir empty and when 5 feet of water was flowing over tlie crest.

Prtliminayy Tro;7i:s. — The reservoir and the first i)umping-station are situated at the bottom of a dee]) valley some miles from the nearest railway, and as all material except stone for the concrete, of which the weir was built, had to be brought from a distance, the first work juit in hand was the construction of a tram line, to the standard railway-gauge of the State, starting from Alundaring station, on the existing line of railway. The next c[nestion Avas the provision, at a com paratively Avaterless spot, of a permanent sn])ply of Avater lit for the use of the many men to be employed, as Avell as for the Avorks. The requirements Avere met by constructing, in the bed of the future reseiwoir, and about 9 chains above the Aveir- wall, a temporary concrete dam, impounding about 20 million gallons, and by form ing, from the by-Avash with Avhicli this small reser\mir Avas provided, a channel capable of carrying aAvay 100 million gallons ])er diem. The channel was formed for the most ])art of open cut, but a timber flume carried the flood-Avaters across the weir-site.

Foundations. — Denerally speaking the conntry at the reservoir site is very rocky, consisting largely of undecomposed granite, traversed by intrusive basaltic dykes, Avhose direction is mostly at right angles to the course of the river. At the site of the weir, however, the granite showed out particularly clearly, and the few trial-shafts, put down AAfliere the rock was shattered, reached solid granite at no great depth, the deepest of the shafts being only 20 feet dee}) from the ground- surface. On opening up the foundations, lioweAmr, it was discovered that the rock was nothing like as solid as surface indications and trial-pits promised; for on the right bank a large portion of what at first a]jpeared to be bedrock was found to consist of an immense boulder with a large cavity below it; and under the bed of the river tlie granite was very badly fissured over the full Avidtli of the founda tions. It Avas not possilfle to Auny the site, as the disruption was found to extend both up and down stream for a considerable distance; and there Avas no alternative but to follow the fissure down, which Avas done until a depth of 90 feet below river-

West Austr.Vlian Mining Practice

bed Avas reached. At this level the tilling material in the fissnre Avas found to be so compact that it Avas but slightly eroded by a jet of Avater discharged under a l)ressure of 250 lb. per square inch. It having been seen that the fissure had a northern underlay a vertical boring Avas iioav made on the north bank of the river, Avhich cut the fissure at al)Out 165 feet beloA\' river-bed, and Avas continued for a further depth of 52 feet. The bore Avas then filled Avith Avater, and the material in the fault Avas subjected to a hydrostatic pressure equivalent to a head of 690 feet, Avhicli Avas maintained for 1 hours', during Avhich time the foot and hanging- Avails of the fissure, and the line of fissure at the bottom of the excavations, Avere all care fully examined; but no signs of moisture could be detected. It AA’as concluded that the material iu the fissure, at a depth Avhich the excavations had then attained, Avas impervious to Avater. and that it would, therefore, be safe to erect the Aveir thereon.

M here the wall AAmuld be highest, that is, Avhere the fissure occurred in the foundations, the excavations Avere carried down about 15 feet from the building line in a vertical direction on the up-stream face; but as one of the basaltic dykes crosses the valley a short distance away on the doAvn-stream side, it was considered necessary to remove the Avhole of the niateilal between the hani>ing-wall of the dyke and what would otherwise have been the toe of the Aveir. The concrete filling of foundations Avas carried n]) to bed-leAml on the up-stream face, but on the lower side the mass filling Avas stopped 18 feet below bed-leAml, and the Avail ])roper was begun to the designed section. The granite 1)eds, or floors, Avere deeply chased in longitudinal rows, about 6 feet wide and 3 feet deep, and the toe of the Avall-batter. where it met the granite floor, Avas channelled the Avhole length to key the concrete in.

The great inecpiality in the depth of the foundations, and their apparent doubtfulness for a Avork of this magnitude, haA’e not a]Apreciably affected the weir; for although Amry fine vertical lines, such as iiiAmriably occur in the concrete lining of service-reseiwoirs in hot countries, haAm made their appearance here, they have not extended, and any slight sweats haAe taken up.

Draivwg-off and Scouring Arrangements. — The reservoir is provided with tAvo A-ahm-toAvers constructed of concrete. The inner tower (Fig. 10. Plate XIII), situ ated on the reserAmir side of the weir, was built into, and concurrently with, the main wall, being api'u’oximately semi-circular in section. The outer-valve tower is rect angular in section, and is situated 175 feet down stream from the centre of the weir- wall, being connected thereAA’ith by a Auaduct, AAdiich carries the outlet and scour-pipes, all solidly bedded in concrete, as far out as the outer Amlve-house. Ingress to the inner AmlA’e-tower is obtained by means of a steel gangway running over the crest of the Aveir, and su])ported thei’eon by granite cut-Avater piers, 52 feet a]Aart be tween centres. '

Provision is made for draAving Avater from the reseiwoir at three different leAmls, namely, at 251/2 feet- 53 feet, and 80 feet beloAv full-supply level, by means of 24-inch cast-iron bell-mouthed ]Aipes, passing through the Aml\m-tower wall into a cast-iron stand-post. Each draw-off inlet is proAuded with a stop-Arnh’-e placed in the valve-chamber, from which A’ah'e-rods are cai'ried up to beAml-geared headstocks. all placed on the upper Audve-tower floor, Avhich is 1 foot 9 inches aboAm maximum flood-water leAml of the reserAmir.

WES'l' AUSTRALIAN MINING PRACTICE

G OOLo A r£) 1 iS yJA'f £ A - -5U P]F>>L7

' limJtfiiinlih

k IT')-'!-

'nmavoia

‘Ov'i'-trPox mi/liin fel-i

mm

/

,Sj

Valvc-Tower.

trOITOAHT M:ArjAaT8UA T8aW

M

Water Supply

Over each inlet are placed screens which can be removed for cleaning by means of chains worked by winches carried on an outer platform rnnning round the valve-tower, and sipjported therefrom by brackets. Two 24-inch cast-iron spigot- and-fancet ontlet-piy)es pass from the stand-post, at 80 feet lielow -supply level, through the weir-wall to the outer valve-tower. Each outlet is provided with a stop-valve in the inner valve-tower, and these are regulated similarly to the valves on the reservoir-inlets.

A .30-inch sconr-pipe, leading from a fore-bay 90 feet below full-supply level, ]‘nns through the inner valve-tower, and through the weir-wall into the outer valve- tower. Tt is ])rovided with a stop-valve in the inner tower, which is worked by a worm-geared headstock placed on the upper floor. From the outer valve-tower the scour ymsses into the river, where it has its discharge. Both the outlet-pipes and the scour-pipe are provided with valves in the outer valve-tower, which will be brought into use only in the event of accidents to the regulating-valves in the inner valve-tower. Any water soaking through the wall of the inner valve-tower is led into a , whence it can be lifted into the sconr-pipe by means of a water ejector, supplied with pressure-water from the lowest inlet. At the outer valve-tower the two 24-inch outlet-pipes junction into a 30-inch pipe, which runs to the stand-pipe in front of the engines at No. 1 Station.

The details of all the ironwork used in the construction of the weir were drawn out in the State, and all ironwork was obtained from Great Britain. It speaks well both for the accuracy displayed in the preparation of the drawings, and for the care exercised in the manufacture of the various appliances, that when be ing groni)ed together as the work progressed, all parts fitted correctly into their respective places, without any alteration whatever.

The site of the reservoir, about 800 acres in extent, was grubbed and cleared, and all fallen timber and decaying vegetable-matter was taken out of the river bed and Imrned; later on the suckers and scrub were again cut down and burned. About 20,000 acres of the lower catchment-area was ringbarked, with the object of increasing the inflow.

A concrete-lined spill-water basin, about 150 feet long by 100 feet wide, is constructed in the bed of the river, at the toe of the wall, with a depth of water of about 10 feet. The water is confined by a mound across the river-bed, constructed of rubble faced with concrete.

The excavations for the foundations were begun in May, 1898, and on their completion in January, 1900, the building of the wall was started, and was carried on both day and night until completion in June, 1902, an electric-lighting plant and eight arc lamps placed at points of vantage affording ample light for operations by night.

About 30,000 cubic yards of spalls for crushing to concrete size, were selected from the material obtained in the excavation of the foundations. For the plums and the balance of the spalls required, a quarry was opened on the north bank of the stream, below the weir, and about 70 feet above river-bed.

The weir and all accessories were built of concrete, but in the former, large rough granite blocks, just as quarried, were introduced into the concrete. It was

West Australian Mining Practice

originally intended to build tbe wall witb 5U per cent, of these large blocks; 1jut with out proper plant, which was not available, hautlling would have been very expensive. The concrete consisted of 5 parts by measurement of granite crushed to 2y2-iuch guage, 2 parts of cleaned sand and 1 part of Portland cement. So long as the wall remained below the level of the mixing-house, tbe mixture was conveyed to the work on an endless conveyor working in a trough, with travelling-boards secured by ropes and spaced 2 feet apart, thus ensuring that the heavier aggregate was not separated from the matrix on the way. Later, the concrete was conveyed on a trolley-line in skips, to a large derrick crane, which lifted the skips on to tem porary tram-lines on the growing-wall; they were then pushed by hand to a travel ling steam-crane which lifted each skip in a bridle, overturned, emptied and re turned it to its carriage. The concrete was spread and rammed by hand, the various layers being broken up so far as the width of wall would allow, in order to break bond in both beds and joints; and in addition, the large rough blocks, up to 2 cubic yards in volume, were deposited and thorouglily bedded and grouted, in order to key tlie bedding-planes together.

For the first 10 feet the batter was lined and the concrete retained by rubble masonry, but above this level wooden framing was substituted. This framing was of Oregon pine, and consisted of uprights 9 inches by 3 inches, and 15 feet long, cut to the sweep of the wall section, spaced 3 feet apart and closely lined on the wall face with 12-inch by V2-iiich Oregon boards. For the tirst few feet upwards, the studs were held in position by shores, but later they were bored foi

l-inch bolts, about 18 inches long, at vertical intervals of 3 feet. Each bolt was fitted with an 8-inch by 3-inch by %-inch iron screwed washer- plate, which was built into the concrete, and remained there after the bolts were withdrawn and the holes grouted. Each vertical stud was

lap- jointed and bolted to the succeeding one, tlie lap being sufficient to allow of two bolt-holds in the concrete before the lower lioards were removed. No cross stays or ties were used across the wall, and the front and back framings were in dependent. The uprights were aligned throughout with theodolite, the heads of each section being cut oft to the required level and fixed to tlie width of wall corresponding with that level, with an allowance for outward ])ressure of the wet concrete. Rendering of the face was not desired or found necessary, as great care was taken, when depositing the wet concrete in contact with the moulding-lioards, to keep all stone well back with straight spades, and a good finished face resulted on stripp ing. The valve-tower and viaduct, which were carried up with the main wall, were similarly built between moulding-boards, the frames inside and out being formed of upright studs, cross-silled and lagged with 4-inch by Ihs-inch tongued and grooved Oregon boards fixed vertically.

The Pipe Line. — The points on which the Commission of English engineers were asked to advise were, as regards pipes and main generally: —

(a) “Whether the pipes should be laid in a trench and covered in, or left exposed to view.”

(5) “Whether it would be safe to rivet up the whole line of pipes, or whether joints, to allow for contraction and expansion, are necessary ; the kind of joint most suitable, should they be necessary.”

Watf.R Suppt.Y

(c) “]\Iateiia] and method of manufacture of ])ipei3, whether welded or riveted, and whether welding and riveting sliall be scpiare or spiral.” The use of cast iron being prohibited by the cost and the difficulty of freight l)oth by sea and land, the (.Commissioners were not to take it into account.

(d) “The diameter and tldckness of pi])es, and method of protecting.”

As regards (n), the Commissioners were informed that there were iJOSsil)ly deleterious salts in the soil of a large part of the district through which the aque duct would pass; and, for this reason, and also in order to avoid pressure on the empty pipes, to save the exjieiise of trenching, and es])ecially to facilitate detec tion and suppression of leakage, they recommended that the pipes should be laid above ground, uncovered, with ex])ansion joints.

The Commission recommended that the pi])es shonld he of steel throughout, supported on bolsters, and riveted iq) in lengths of about tlO feet, with expansion joints at these intervals, and anchor joints midway, fixed to masses of concrete or piles, in order to prevent the pi])es from creeping. The minimum thickness was fixed at 3-l(iths inch; and the pipes were to l)e longitudinally liveted where the pres sure was such that the thickness of shell for riveted pipes was not required to be greater than inch, and welded for all higher pressures; with a minimum thickness of inch.

Number of Lengths of Pipe.

Class of Pipi-:.

ZJh feet long with plates inch thick and of internal diameter.

28 feet long with internal diameter 31 inches at larger end and reduced at smaller end according to thickness of plates to form telescopic joint.

26 inches.

2l\ inches.

29 inches.

Of 3-16 inch Plate.

Of l-inch Plate.

Of 5-16 inch Plate.

Welded —

5,592

4,393

5,710

—

—

—

Riveted —

—

—

—

23,425

19,759

3,257

Tenders for the pipes were accordingly invited from Australia, Eurojie and America, the quantities specified for being as shown in the foregoing table. Ten derers were at the same time invited to submit alternative prices for any other kind of pipe which they desired to put forward. The lowest of the tenders received were as follows, the prices being for delivery in the State at a point 22 miles in land: —

Class of Pipe.

Lowest Tenders Received in

Europe.

Australia.

Riveted Pipes

£

782,708

£

682,827

Welded ,,

472,600

—

Locking-bar Pipes in lieu of welded pipes —

—

239,868

Total —

yi, 255, 308

£922,695

West Australian Mining Practice

The loekiii'-har pipe, lor wiiich alteniatU'e tenders were received, had been considered l)y the Commission and favourably commented on, but was not recom mended I'or so large a scheme, because ]n-oof of its successful manufacture and use on any considerable scale was not then availal)le. Subsequently, however, and be fore receii)t of the tenders, 10 miles of main, 2r)>/k inches in diameter, had been laid in South Australia. It had been found that ]i])es made fi'om plate and fresh

from tlie closingmiacliine would Avithstand a pressure of 400 lb. per square inch — or nearly twice Avhat Avould be alloAved continuously in ])ractice on pipes of this thick ness of ))late — Avithout a AAmej); and, moreoAmr, all piAes Avhich did not stand the test (‘onid be passed back to the closing-machine to be reclosed, instead of being sub jected to the usual caulking-jArocesses so injurious generally to the plates and jointings. Practical use on a fair length of main also showed that the jointing could be successfully accomi)lished, thus leaving only (piestions of comparative cost and conq)arative usefulness to be considered in deciding AAdiether the new pipe should or should not be used in place of welded and riveted i)ipes.

Taking first the Australian prices for locking-bar i)ipes and contrasting them AA’ith those for Avelded pipes, the saving is seen to be A-ery marked, being within a feAV ])Ounds of 50 per cent. Moreover, the price of locking-bar pipes was but little more than that of riveted pipes. The loAvest tenderers AAmre therefore asked to con sider the matter again, and they quoted ])]‘ices for the locking-bar pii)es which con trasted as folloAvs Avith those receiAmd for the riAmted pipes; —

Thickness of Meta! in Pipe.

Riveted

Pipe.

Lockin

4 Bar Pipe.

£

s.

d.

£

s.

d.

3/t6

5/16

Making a reduction of l-16th inch from the thickness of the plate to allow for corrosion and contingencies, and assuming a safe Avorking-]Aressure of Tlh tons per s(|uare inch of net section of metal, the safe head of water on pipes of these thick nesses, and 30 inches in diameter, is shoAvn by the following table: —

Thickness of Metal in Pipe.

Safe Working Head.

Riveted Pipe.

Welded Pipe.

Inch.

Feet,

Feet.

3/16

5/16

The locking-bar pipe being as strong as Avoided ])i]Ae it would be possible to effect considerable economy by using 3-lfith inch and Ih-inch locking-bar pipes, in place, resjAectively, of the i/j-inch and 5-16th inch riveted pipes which had been

Water Supply

speciiiecl originally ; but it was recognised in the State, when pipes of so small a thickness as 3-1 6th inch were included in those to be tendered for, that great care would be required in handling them, in order to prevent damage; and one result of the favourably low tenders was that a minimum thickness of f Linch was provided throughout, thus greatly increasing the proluible life of the main in the very portions where the soil is worst, and the variations in temperature greatest. Moreover, by having one thickness and one diameter throughout, the contractors were induced to make a further reduction of 5s. per pipe, so that the whole length of main was laid with pipes 30 inches in diameter, thus effecting some saving in the capital cost of the pum])s, as Avell as in the cost of pumping.

Summing u]) the position the results of adopting locking-bar i)i])es and a uniform diameter tliroughout are these: The section of the ground traversed by the pipe-line is such that, considered purely from a |)oint of view of obtaining minimum pressures on the main throughout, it would be advis able to vary the diameters and thus use up su])erfluous head; but the variation of pressure with a uniform diameter could not be large if the pump ing-stations were suitably located, and this slight disadvantage was considered to be more than counterbalanced l)y the reduction in the cost of the pipes and the other advantages attending a uniform, and to some extent larger, main. More over, the substitution of locking-bar for welded pipe, effected a saving of no less than 50 per cent, of the cost of the latter; and, although, as compared with the riveted ]upes tendered for, the locking-bar ])ipes eventually provided cost llVe per cent, more, on the other hand, the latter were considered super-ior in several ways. Their frictional re.sistance, according to older accepted formula, was less in the ratio of 2.5 : 3.1, a difference of 25 per cent.: and the probable damage in handling hr-inch in lieu of 3-16th inch plate pipes would be less, and the probalde life of the pipes would be much longer; for, the actual thickness reciuired for safe working being about as 2 of locking-bar to 3 of riveted pi])e the substitution of Ut-inch plate locking-bar ftipe for 3-16th inch riveted ]:)ipe, meant a provision of 5-21th inch of plate in place of ]-16th inch for corrosion and damage; and the substitution of f4-iiich locking-bar pipe for hi-inch riveted meant a provision of 7-48th inch for corrosion in place of l-16th inch in the case of the riveted pipe, a difference, therefore, of 133 to 233 per cent.

As the adoi)tion of locking-bar pipes olndated the serious and continuous loss of water which was to be anticipated from a pipe having multi tudinous rivet-holes, the question was considered whether the soils in which the pi]ie would have to be laid would tend to shorten its life, and, if so, to what extent. As already mentioned, the natural water obtain able on the goldfields is highly mineralised; moreover, it often contains free acids. Therefore, thin un])rotected pipes in contact with this water could not have any lengthy life — a conclusion which experience has confirmed; but careful analysis of the soils along the pipe-track (Table I ) showed that, Avhere mining operations did not entail distribution of such water on to the soil in which the pipes might be buried, this soil has been so much leached as to have lost many of its harmful p]-o])erties, exce])t, of course, in the salt-impregnated beds of the so-called “lakes.” It was decided, therefore, that in the latter situation the pipes should be laid on

West Au8Tkalian Mining Practice

trestles aljove ground, but covered with a low roof of galvanised iron; and that in the remainder of the section tliey should be buried, thus obviating any necessity for expansion-joints, and permitting, in fact, the use of ordinary lead-jointing;.

77m Coatiny. — In determining the com])osition of the coating to be used, wide extremes of temperatures had to be allowed for. The tierce and continuous heat of the goldfields’ summer, when the temperature in the sun attains ISOdeg to ITddeg. E., is sufficient to render even block asphalt plastic. On the other hand, the frost of winter would injuriously affect too hard a coating; and, moreover, as ex[)eriments showed, the extreme dryness of the soil at certain seasons, to gether with the heat, would very likely cause some loss of essential oils. As the result of a large number of tests of mixtures, made both at the pipe-works and at the head office, the coating used consisted of one part of asphalt and one part of coal-tar, applied as described later, and freely sprinkled with sand while still hot and soft, to reduce the risk of the coating running when exposed in hot weather. No doulit the latter object could have been attained by more boiling, but the harder coating-mixture would have been brittle and more liable to flake off the pipes. Even the coating used ran to some extent when ex})osed for many days to the hot sun; but ail exposure of metal, owing to this and other damage, was systematically made good just before the pipes were buried. The inside of the l)il)es was similarly coated — except, of course, that no sand was applied; but, as the water |)assing through is soft, although containing “20 grains of solids per gallon, and as vegetalde acids are absent, much corrosion of the interior surface is not anticipated; and where the pipes have been emptied and opened 12 months after water started to pass continuously through them, the interior has appeared to be as clean and good as when they were first laid.

PLATC 1 thick, LOCKINC-BAH 7 LBS PER LINEAL TOOT TOR ALL. HEADS UP TO 250 FtET

PLATE THICK LOCniNG-BAR LQS PER LINEAL FOOT row AU HEADS ABOVE SOO FEET

Scale 3 Inchts 1 Foot

Inches O I 2 3 5 G Inches

' - 1 - 1 - 1 ! L - 1

Fig'. 103.

Joints. — A sinpile sleeve joint (Figs. 103) was adopted, the rings being 8 inches wide, and i/o-inch larger internally than the ])ipe externally, to allow for slight variations in the ring, and to permit of the use of lead filling throughout. For working-heads of 320 feet and less, the section of ring used was as shown in Fig.

Water Supply

104, tlie 'weiglit being 126 lb.; but for heads of luoi-e than 320 feet a stronger form Avas used, as siiowii in Pig. 105, the weight per ring l)eing 160 lb. The tinished jointing has i)roved very effective, the loss tlirougli leakage being small. Prom the pipes alone, on Sections 1-5, it Avas found to be 343 gallons ]Aer mile per diem. Prom the Avhole length of 295 miles betAveen the storage-reservoir at Mundaring and the last pumping-station it was found to be 480 gallons per mile per diem, over 10 months’ Avorking. Tliis ligure includes losses due to evaporation and per colation from nine pumping and break-])ressure reseiwoii's of contents aggregating Ibi/o million gallons.

Fig". 104. Fig'. 105.

As a direct line from tlie Helena reservoir to (’oolgardie does not deviate far from the railway already built to the goldlields, it Avas resolved that from Nor- than eastward the })i]Aes should be laid ])arallel with the raiLvay, and at a distance of 45 feet therefrom, thus gaining the great adAumtage of easy carriage, and, sub sequently, of easy supply of Avater to the railway; but 1)etAveen the Aveir and Nor- tham the railway Avas deviated from, in order to shorten the distance, and also for the purpose of traAmrsing higher country and thus reducing the pressure on the pipe.

At intervals of about 5 miles stop valves are inserted, the diameter of the main being reduced by cast steel reducing-pieces to 21 inches. Where long rising gradients occur reflux-vahms are placed, the pi]>e lieing similarly reduced. Sconr- Amlves are provided where required at l)oth stop-valves and reflux-valves. The stop-valves are actuated by slow-motion gearing, and, on sections Avhere the water- hammer was likely to be considerable, small by-passes were introduced, and so con trolled that the water was brought to rest very sloAvly. xVir-Auil ves of the Glenfield pattern were placed at all summits, a nest of three being placed at the highest points, a nest of two at intermediate ])oints, and a single A'alve at the lowest points. These valves are of the double type, provision being made for the large escape of air Avhen charging the main, while air accumulating in the ihpe is automatically dis charged. This automatic discharge, instead of being obtained by Auirying the diameter of the ball, is effected by Amriation in the diameter of the orifice in the nipple. By this arrangement the ni])ple-orifices for the high ])oints, Avhere the pressure is light but Avhere larger volumes of air accumulate, are of the largest diameter, and consequently afford the maximum ]Arovision for the discharge of air.

Manufacture of the Pipes. — Pigs. 103 sIioav the section of the ihpe used, the dimensions Auirying according to the head. A pipe consists of tAvo })lates, each of the full length of the pipe, and each bent to a semicircle. The edges are burre<l or beaded to the shape of a dovetail, and are inserted in the open jaws of heavy

WEST xVUSTUALIAN MINING PRACTICE

longitudinal bars, wliicli are subsequently closed cold on to the edge of the plates, thus forming longitudinal dovetail joints. The steel used in both plates and bars was open-hearth basic steel, with a specilied tensile strength at lirst of not less than 25 tons, or more than 29 tons, per square inch. Experience gained in the manufacture of the i)ipes, however, showed that steel of this quality Avas somewhat too hard for the liars, which oAving to the cold working, failed under test by the bursting of the juAvs liefore the plates were riqitured. It was also found that when bars weighing GW lb. and 7% lb- pei' lineal foot Avere used, respectively, Avith Ci-inch and 5-lGth inch plates, the bars failed before developing the full strength of the plate; consequently, the respecthm weights of the bars Avein in creased to 7 11). and 8Et lb. per lineal foot, the steel in the bars being of a tensile strength of betAveen 22 tons and 2G tons ])er square inch. Erom each week’s out- ])ut of i)ipes at the Avorks i)ieces Avere cut and tested to destruction. The results are giAmn in Table 11.

The pipes Avere made in Western Australia from imported plates and bars. Cf the former, one-half Avere brought from Germany and the balance from America; but all the bars (and the joint-rings) Avere obtained from England. The plates, which Avere a trille over 28 feet long by 4 feet wide, were first passed through hori zontal rollers, three above and three beloAV, for the ])urpose of taking out all kinks and rendering the plates perfectly straight. They were then cut square and to the exact length of 28 feet. The planing and dovetailing machine next cut them to the exact width, and then Imrred the edges by 7iieans of rollers to form the beading for the dovetail joint. The plates next passed through a longitudinal i)ress, wherein both edges Avere given the required curvature, thus avoiding any necessity for the beading or dovetail being passed betAveen and damaged in the curving-rollers to which the i)lates Avere noAv brought, to be l)ent into semicircles in the usual way. On completion of this process most of the scale had been loosened and detached, and the jAlates, having been thoroughly cleansed of all remaining scale and rust, were ready to be formed into pipes. One semi-circular ])late Avas noAv placed in a row of half-circular cramps, resting on seats, and a locking-bar Avas fitted over each edge. Another semi-circular plate Avas then inverted and lowered until its edges rested in the iqiper grooves of the locking-bars. The upper halves of the cramjs Avere then i)laced over the top of the pipe and connected to the bottom halves, and the plates AAmre brought firmly home into the grooAms of the locking-bars by tight ening the eranqis with cotter-})ins. The pipe in its encircling (U'amps was then coiiA’-eyed to a hydraulic closing machine capable of developing a pressure of about 1,20G tons, Avherein the locking-bars were pressed on to the plates, complet ing the manufacture of the pipe. The whole of the operations were performed with out heating plates or bars.

Each ])ii)e, liefore being passed, Avas subjected to a hydraulic pressure of 400 lb. i)er square inch. The closing of the locking-bars was so effectual that only a small i)ercentage of the pipes were found to sweat at the bars. These were re turned to the closing machine and re-pressed, and this Avas found to stop the SAveating effectually. About fifty pipes failed altogether in the joint under this test.

After being tested and passed the pi])es Avere coated. They were first heated to a temperature of SOOdegs. F. and then placed in a bath consisting of a solution

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of ordinary gas-tar and Trinidad asphalt, in the })roportions already' stated and kept at the boiling-point. On lieing lifted from the bath the pipes were allowed to drain for about a minute, and were then revolved in a machine while a jet of cold air was forced through them, for the purpose of ensuring that the coating should set in a uniform thickness. When it had cooled considerably, and just before setting, a sprinkling of sand was thrown over the out.side of the pipe and gently pressed into tlie coating by means of rollers.

After all initial dillicnlties common to new methods of manufacture had been overcome, the pipes were turned out finished at the rate of 150 to 160 per diem from two factories, each of which worked two shifts of 8 hours each.

Two points required special attention in the construction and use of this pixie. The first was that the jaws of the locking-bar should be x>ressed well home on to the xilates, no caulking of the joint being xierniitted at the manufactory. Unless this was ver) carefully done, water would enter at the ends and work along the xiilie at B in Figs. 4, until some exit was reached. Examination of the iiiiie, and slight caulking at the ends before placing in trenches, disxiosed of such cases of oxjening of joints as were caused in a comparatively light pqie by handling and exxiosure after des]iatch from the manu factory. The second xioint also related to the necessity for closely xressing home the locking-bar, as caulking was not possible at the xioints marked A: the difficulty was overcome by cutting or chixixiing away the xiortions marked A. pjg

Locking-Bar Ano Plate"

BEFORE Closing of bar

Locking-Bar And Plates After Closing Of Bar

Conveying, Distributing , and Unloading Pipes. — The whole of the X-hxies had to be conveyed on the trucks of a single-line railway of 3-foot 6-inch gauge. Most of them were laid alongside this line, but those which had to be taken across country where the xiptUine deviated from the railway were conveyed from sta tions or sidings on sx3ecially constructed carriages. The had to be distri buted from the trains very quickly, so that tlie ordinary traffic on a fairly hard- worked railway would not l)e interfered with. The railway-wagons being each shorter than a xixe-length, two bogie-trucks were firmly couxled, fhus giving a clear floor-length of 30 feet, and the xipes were placed thereon in three tiers. The bottom three xipes were kept in X'osition on the trucks by means of chocks with removable gib-bolts and three recessed bolsters, each xhaced across and over the bottom tier of pixies, carried the second layer, also of three xhles, which, in turn, were held in xosition by means of chocks and gib-bolts, similar to those used for the bottom tier. In the recesses of the second layer of pipes a third tier of two pipes was xlaced. A truck-load therefore consisted of eight pipes, and the trucks were sent forward in trains of eleven to thirteen.

The unloading contingent of men, consisting of four gangs, who, up to the arrival of the train, had' been engaged on the excavation of the pipe-trench, then took charge. Each of these gangs consisted of six men, including a leading hand who controlled the gang’s operations. Each gang had generally three trucks to unload, and when the train consisted of an odd number of trucks, the extra work was allotted to the gang first getting to work. The average time occupied in unloading,

'240

West Australian Mlninu Practice

Trom tlie time the loaded train left the siding until it returned thereto with the empties, was about 1 lionr and 20 minutes, bnt the unloading was frequently done in less than 1 hour. During the remainder of the day the unloading gangs were kept at Avork on the excaAuition of the pipe trench, sections of AAdiich had been left for this purpose. This system Avorked admirably, there being considerable rivalry betAveen the various unloading gangs, and the general raihvay traffic was not inter rupted.

Joints. — As the whole length of main is of nniform diameter, the possibility of using machinery in place of hand-caulking of the lead joints Avas considered at an early stage. Carefnl trial at headquarters of joints caulked by hand and by a machine devised bA a local lirm, demonstiated that, Avhereas the machine-made joints Avhen sul)jected to hydraulic pressure attaining 400 Ih. per square inch re mained quite Avater-tight, on the other hand slight SAA'cats and pin squirts manifested themselves in the hand-made trial-joints submitted to the same test. As a MO-inch pipe of f4-iuch ])late s])rings somewhat, even under the impact of a Amry light )low fi'om the caulking-hammer, it is somewhat difficult to get hand-caulkers to finish a join water-tight; moreover, in ])ractice, men Avorking in constrained positions for long hours, in manholes nnder the ]fipe-joints, cannot be expected to do uniformly good Avork. On the other

Fig'. 107.

hand, the machine-caulking can l)e done l)y pressui'e applied uniforndy on both sides of the joint-ring, and quite as uniformly on the lower as on the up])er side of the pipe. Machine-canlking Avas, therefore, decided on, Avith the good results in freedom from leakage already stated.

The caulking-machinery consisted of a ])ortable oil-engine of the spontaneons- ignition ty])e, built in Australia, and of about 5/2 Inh.p. The underframe of the engine also carried a dynamo Avhich Avas helt-driAmn off the engine fly-Avheel. The current Avas transmitted through a cable Ut mile in length, so that about fA mile of i)ipe could be caulked befoi'e moving the generating-chant to a fresh position. The cable Avas coiled on a drum carried on the after part of the transport, also carrying the canlking-machine, and a i)lng contact was used for connecting cable and motor, so as to pennit of unham])ered coiling and uncoiling of the cable on the drum. The canlking-machine (Pigs. 11 and 12, Plate Xl\") aauis in tAvo liahms, one litting over and the other under the joints of the main, and on the top half of the outer frame was carried the electric motor (of 2 h.]).), which was belt-connected to

z

ft

m

z

to witli the litly done in :s were kept jen left for ible rivalry as not inter-

0 possibility i<iered at an and by a achine-made are inch re- pin squirts the same even under s somewhat areover, in boles under u the other

-j)j)er side of I results in

qtontaneous- ame of the wheel. The sh ])Osition. nsiort, also .ecting' cable (-able on the halves, one half of the connected to

Watkr Supplt

a shaft, and, by means of intermediate gearing, worked the rims holding the caulk ing-tools (Fig. 107). Tliese rims or racks were guided by small, hardened steel rollers, grooved on the outer circumferences of the racks, but plain on the inner circum ference. Into jaws on the racks were slipped the caulking-tools, two in each rack, one operating on the upper half of the joint and the other on the lower half, i.e., on the underside of the pipe.

The caulking-machine was mounted on a transport, on which it was carried along the top of the pipe, from joint to joint, the lower half of the machine being slung on the transport, side by side with the upper half. On arrival at a fresh joint the lower half was lifted off, placed over the joint, and slid round it to the underside; the upper half was then lowered, and the two halves were fastened to gether, racks were clipped, and the tools placed in position, the plug-connection between drum and motor was made, and the machine was started, the caulking-tools working round the ]hpe backwards and forwards until the lead was pressed home. The number of semi-revolutions found necessary ranged from five, where the caulking-rollers were i/4-inch thick, to seven, where 5-16th inch or %-inch rollers had to be used to meet the varmng distance between the inner surface of the joint ring and the outer surface of the pipe. On completion of the caulking these tools were replaced by knives, which cut off the fillet in the last semi-i'evolution, bringing the racks back to their original position and thus permitting the machine to be dis mantled and moved to the next joint. When once fairly started the operations were carried 011 without hitches, and the machinery of all descriptions, including motors and dynamos, worked well, notwithstanding that it was usually working in a cloud of dust, due to the proximity of the trench-filling operations.

Each installation required three men (one a mechanic) for the working and transport of the caulking-machine, one man for the engine and dynamo, and two hand-caulkers, whose special function was to caulk at the locking-bars, whose pro jections prevented the rollers from working right round the pipe. In addition there were charges for parts of the time of mechanics and others whose duty it was to keep the electrical and other machinery in repair. The whole immediate cost of an installation per diem amounted to £5 Is. 4d.; and as the average day’s work when the initial difficulties had been overcome was thirty-one joints, the cost per joint was .3s. 3d., or Is. less than hand-caulked joints were actually costing. In addition, the saving in the average size of manhole necessary was 1% cubic yards; and these two savings counterbalanced the whole cost, including the patent-rights of the machinery. There is no doubt that, with the experience gained, machine- caulking could be rendered cheaper than hand-caulking, especially for a circular pipe without projections: but the object in this case was to obtain uniform and cer tain work, and this was attained without extra cost.

Excavation of the Trench. — The surface formation of the country traversed is very irregular. On the plains ironstone conglomerate ]U'edominates, but never extends continuously for more than a few chains at a stretch, being broken by bands of sand, diorite, and granite. In the timbered belts sandy clay is the usual surface soil, but with outcrops of granite, diorite, and schist interspersed. Where at all possible the material to be taken out was loosened by means of ploughs, each drawn by four horses harnessed in single file in the line of trench, and working

West Australian Mining Practice

to any depth recpiired; but the hulk of the trencli Avas taken out by manual labour, and it was necessary to use explosives on more than one-fourth of the total material removed. Where the material could be moved without the use of exjiloswes it was found that the most economical depth of trench, with due regard to cost of obtain ing cover-material, was al)Out 3 feet 3 inches. AVhere the country was harder the trench was taken out to a less depth, the principle kept in Anew being that the cost of the trench, added to the cost of coAer, should be a minimum. Occasionally the contour of the ground would not admit of economical grading in combination with proper alignment for the pi})es, and, in such cases, cost Avas subordinated to the more important consideration of easy alignment of the main. The excavation of the trench was kept well ahead of pipe-distribution, laying, and jointing, but in order to provide continuous Avork for the gangs on these latter operations, should any hitches occur in the arrival of material, sections of trench were left unexca rated at inteixmls.

Laying and Jointing Pipes and Filling in Trenches. — The Avork was divided into sections of about 14 miles each, to be dealt with by one caulking-installation, and Avhen the Avork Avas comiileted the whole gang went forward to the next avail able section. AVhen the works Avere brought into full swing, seven such gangs were at work on several sections, and the class of work performed by each being identi cal, there was considerable i-ivalry between the parties. Bad work, due to haste, was prevented, iiowever, by the appointment of an inspector on each section, who reported directh to the head office, and Avas responsible only for the quality and not for the cost of the work, thus placing these departmental operations on the same footing as those of a contractor. The rate of progress during the last three months, before approaching comjdetion caused disbanding, was, per day of 8 working-hours of seven gangs, one and two-fifth mile of laying, jointing, and complete fiilling-in of trenches. The appliances in use by each gang consisted of two pipe-lowering trestles, four skids, one pipe-expander, one lead-melter and retainer, and the engine and caulking-plant. The lead-running gave great trouble until the lead-melter was devised, after which honeycombing and other similar faults were prevented.

The sequence of the Amrious operations was carefully regulated. Foremost Avere the men repairing the coating in the ])arts damaged during unloading or transportation, or where it had become' defectiAm owing to exposure for a consider able time to the intense summer heat; and in the same set were the pipe-scrapers and locking-bar chi]A]Aers, who chipped or scraped off the coating at each end of a pipe for a distance of about 6 inches, to ensure good lead-running. Next came men cutting manholes, a little ahead of those laying the pipes in the trench, and following these came the ring- setters, who wedged up the joint-ring to such gauge as would give a lead joint of uniform thickness. In succession Avere the lead-runners, Avhose work was, when possible, kept at least forty or fifty joints ahead of the caulking-machine, especially in winter, as showery and cold weather affected the quality of the lead running: thus stoppage in such weather, or- defectiAm Avork which had to be remedied, did not delay the caulking operations. Following on Avere the hand- caulkers, who caulked the joint at the locking bar and for a distance of about 4

Water Supply

inches on each side of it. The best results were olitained, not by allowing the hand- canlking to finish abruptly, but by tapering up to the uncaulked portion; by this means the machine rollers were able to work by degrees well hack on to the hand- caulked portion; with an abrupt finish of the hand caulked portion the machine rollers were liable to race and cause breakages. This racing could, of course, have been avoided by extra care on the men’s part, but at expenditure of unnecessary time, to save which would have entailed the danger of the rollers not being brought far enough along, thus leaving the joint imperfectly caulked at the junction of hand and machine work. After the hand-caulkers came the machine, and as each joint was finished the joint-inspector examined it; pipes were covered to a depth of at least 12 inches as soon as the inspector had passed a joint and it had been tarred, so that the partial filling-in was only two or three joints at most behind the machine. The completion of the filling-in and the formation of the covering hank was always 400 yards or more behind the machine.

Charging the Main. — By April 13, 1902, the works were sufficiently far advanced to enable pumping to he commenced with one of the engines at No. 1 station. No trouble was experienced in getting the engines under way; in fact, practically no hitch whatever occurred at any of the eight pumping-stations, and after once starting at any station the machinery was in condition to be worked, and was worked, whenever desirable. By April 22, the water had reached the Cunderdin Reservoir, at mile 77. Four months now elapsed before the laying and jointing of the next section was com]deted, and it was not till August 22, 1902, that the water reached the Merredin receifing tank at mile 140. Some little trouble was experienced in charging this section, through the joints leaking, due mostly, to the subsidence of the pipes laid across the bad ground in the bed of the Mortlock River and adjacent soft country. It was through leakage of some of tb.e joints on this section that what may be described as “ sand cuts ” were first ex perienced. They were caused by the joint action of the escaping water and the fall ing sandy covering playing together on a small portion of the outer surface of the pipe. This action is somewhat similar to that of the sand-blast, and, under favour able conditions, one of the thin pipes used could be cut through in 4 to 6 hours. Fortunately only six cases of the kind have been experienced so far. If dis covered early the placing of an encircling band on the ]:)ipe (such bands were kept in readiness) met the difficulty; but if the plate of which the pipe was made had a hole entirely or nearly ci>t through, a length of the main had to be emptied and the damaged pipe was replaced. To guard against occurrences of this nature the upper halves of the lead joints were subsequently kept uncovered for some little time in country of a sandy nature, and where the main is under a head of 300 feet or more. The water reached the Coolgardie service-reservoir, at mile 328, on December 22, 1902, and finally, the Kalgoorlie service-reservoir on January' 16, 1903,

about 8 months after the charging of the main was started. The pumping was re.stricted to an amount sufficient to fill about 12 to 15 miles of main per day, and at this rate of charging no trouble from air-pocketing was experienced, it be ing found that the air-valves had sufficient discharging-capacity to pass the volume of displaced and escaping air. The whole or ]-art of the main has now been convey ing water for nearly 21/2 years without a burst having resulted, either in the main

WF.ST AUS4’RAr;iAN PRACIGrF

or in the valves or other specials; the only occasions on which it has been neces sary to empty any portion of the main have been when the “sand cats” have occurred.

The Pumping- Machinery. — Frictional Besistance of Pipes. — It was orig-inally calculated that for a discharge of 5 million gallons per diem through 30-inch riveted ]n]ies the frictional resistance per mile would he ecpiivalent to a head of 4 feet, which was ol;)tained by a])plying Kutter’s formula with a coefficient of roughness of 0.015, a figure deduced from the measured frictional resistance of the 48-inch riveted pipe of the East Jersey (U.S.) Water Com])any. But the change to a much smoother pipe allowed of a considerably reduced provision. The Commission of Engli.sh engineers had proposed a frictional allowance of 2.5 feet per mile for welded pipe; but in view of the class of water to be dealt with this allowance was increased by 20 per cent. ; and as it was further determined to increase the daily quantity to 5,600,000 gallons, the ultimate allowance was raised to 3.76 feet per mile. On com- ]iletion of the works, two tests, each of 12 hours’ duration, were made, one over 22 miles and the other over 12 miles of pipe, the results on reduction showing an average resistance equal to 2.25 feet per mile for a discharge of 5,000,000 gallons ]-)er diem, or 2.8 feet for 5,600,000 gallons. These results, being for clean pipes, are considerably less than tlie ultimate estimates; and this was foreseen, for reference to Pig. 7 (Plate XTTT) shows that the main was laid to even less fall than 2/4 feet per mile, in order to save unnecessary present ])umping.

The total ultimate friction-head for the whole distance from the weir to the main service reservoir at mile 3071/2 of the aqueduct, calculated at 3.76 feet per mile, amounts to 1,156 feet, and the natural lift to 1,290 feet; and the aggregate loss at seven pumping-stations for reservoir provision being 122 feet, the total head to he provided for is 2,568 feet; but elevated ground between pumping-stations Nos. 2 and 3 made it necessary to raise water 87 feet higher than if the slope had been gradual, thus making the total head to be pumped against 2,655 feet.

The great advisability of keeping the machinery to uniform size and pattern finally determined that the pumping-stations, eight in number, should provide for a total lift, including friction, of 2,700 feet — or 45 feet more than was absolutely necessary, namely, 450 feet at the first four stations, and 225 feet at the last four. The waste head thus amounts to a trifle less than IfiJ per cent. Moreover, in regard to the advisability of uniformity, it was further decided that the first four stations should be fitted with three groups of machinery, any two of which should be capable of performing the required work; and that the last four stations should similarly be fitted with two groups, each capable of lifting the full quantity per diem. The ]iower necessary had thus to be the same in every group, namely, 265 effective h.p., but to allow for deterioration and contiTigencies the ]mnqfing ]mwer contracted for was nearly 303/4 h.p., or about 1414 per cent, extra.

The requirements and provisions may be summed up thus: —

Effective horse-power necessary

provided for work

Tt.P.

3.r42

2,426

as reserve

WATlUi SUPPI.Y

Tenders for the necessary pumping machinery were invited in April, 1899, makers being permitted to submit alternatives as in the case of the pipes. In the result a contract was entered into with Messrs. Janies Simpson and Co., in March, 1900, for twenty groups of machinery, at an aggregate cost of £241,750, excluding spares, but including erection. A detailed description of the machinery is outside the scope of this chapter, which, however, would be incomplete without the following- brief account, and results of tests.

Description of Macinnery.—The pumping-iJant consists throughout of almost identical sets, the only difference being that in the lirst four stations the pump- plungers are 15 inches in diameter, working against a specified head of 450 feet, while in the second four stations the diameter is 21 inches and the head 225 feet. The engines are horizontal, six-cylinder, lugh-duty, triple expansion, surface-con densing engines of the Worthington duplex, ciirect-acting type, the diameters of the high, intermediate, and low-pressure cylinders being respectively IG inches, 25 inches, and 46 inches, the normal stroke of tiie pump-plungers 36 inches, and the piston-speed 150 feet per minute. The pump-plungers are externally and centrally packed, and directly connected with the steam-pistons. The pump-valves are of stamped bronze. The steam-cylinders are jacketed throughout on heads and barrels with steam at boiler pressure, and the steam is re-heated on its passage both from the high-pressure to the intermediate-pressure, and from the intermedi ate-pressure to the low-pressure cylinder. The re-heater tubes which draw their steam from the cylinder- jackets are placed low, thus being the means of drainage for both cylinders and jackets. The steaoi distribution is controlled by Corliss valves, placed in the cylinder-heads, and the cut-off in all cylinders is adjustable by hand while the engines are running. From the air-pump the condensed steam passes through an exhaust heater placed in the exhaust steam-main to the condenser, and is delivered into an elevated feed-tank in place of the ordinary hot-well. From this tank the water gravitates to a Webster heater and oil-separator, where it is further heated by admixture with the jacket-condensation and with the exhaust from the boiler feed pump. From the heater the feed-water is pumped by a Worth ington feed-pump through the economizer back to the boilers. Steam is supplied by a nest of Babcock-WTlcox water-tube boilers, each designed to supply the neces sary quantity for one engine, and having eighty-one tubes 18 feet long and 4 inches in diameter, a single drum 23 feet 7 inches long and 4 feet in diameter, with a superheater ])laced between water-tubes and drum. A Green economizer is pro vided for each installation. The chimney-stacks are of steel, 5 feet in diameter; those at the first two stations are 130 feet bigh, at the third and fourth stations 100 feet, and at the last four stations 90 feet.

At six of the pumping-stations, reservoirs 15 to 20 feet deep, have been pro vided adjacent to the machinery, to recei\'e the discharge from the main and to furnish a store for the ])unqDS to draw from; and in order to reduce suction-lift and facilitate pumping the centre line of the pump-plungers has been kept below the top of the reservoir by about 8 feet. At stations Nos. 1 and 3, however, special arrange ments were necessary. At No. 1 the pumps, if connected directly with the main from the large storage-reservoir, would have been subjected to a head of about 100 feet when this reservoir was full; and at No. 3, where there is % mile of main between

West Australian Mining Practice

the large reserve reservoir and the pumps, the latter might have suffered from an undesiralhe hammer. The difficulty was overcome at each place l)y the provision of a stand-pipe open above, from which, as from a reservoir, tlie ]iumps draw.

The stations are Inick-buildings with corrugated-iron roofs. The engines and pumps rest on granite bed-stones, su])ported 1>y brick piers resting in turn on a concrete floor. The pump-ends are bolted down to the ])ed stones, but the cylin der-ends are allowed to move freely on expansion rollers. The greatest care was taken in the laying of the foundations, only the best available material being used;

Fig. 108. Mundaring Weir, Helena River.

and, so far, there has not been the slightest perceptible movement in the foundations of any of the twenty groups of machinery. The lower floors of the engine-rooms are of concrete, rendered with cement mortar, and the upper or working floors ai*e of jarrah timber resting on steel joists. The floors of the boiler-rooms are of concrete.

Efficiency of the Machinery. — The tests provided for by the contract were three, namely: (a) for the duty of the whole machinery under present conditions, that is, head low owing to clean ])ipes and new boilers worked to full pressure; (b) for the duty of the engines and pumps with steam at fiill pressure but the pipes

Water Supply

throttled to obtain ultimate estimated head; and (c) for the capacity of the pumps with the pipes throttled and the boilers worked at 2511). per square inch below pre sent full pressure. Tests of the machinery of 12 hours’ dnratio.n, at two stations to be selected by the engineer, were provided for, and the duty stipulated for was in test (a) 135 million foot-lb. for 160 lb. of local coal worth J 0,000 B.Th.L. per pound, which was taken as the equivalent of 1 cwt. of Welsh (mal; in test (5) 135 million foot-lb. per million British thermal units supplied to the engines and not re turned in ordinary working to the boilers ; and for (c) the full discharge with the terminal effective pressure of the low-pressure (-yiindei's not more than 61/2 Pr square inch, revolutions not more than 25 per minute, and ])iston-si)eed not more than 150 feet per minute.

The stations chosen for testing were Nos. 2 and 8, two groups being picked in the former and one group in the latter. Three separate preparatory tests were made to ascertain the slip of the pumps, the results being 0.6 per cent, at station No. 2, and 0.2 per cent, at station No. 8; and the respective plunger-displacements per foot of travel were, after correction for slip, 7.3645 and 14.7215 gallons. The coal in use varied slightly in quality, the calorific value per pound assigned at station No. 2 being 9,916.7 B.Th.U., and at station No. 8, 10,058 B.Th.U. The values assigned to the combustibles found in the ash-pit were f 1.637 B.Th.U. and 11.142 B.Th.U".

The results of the tests were that in test (u) the duty iier 1,600,000 B.Th.U., the assumed equivalent of 1 cwt. of Welsh coal, was 144.4 million foot-lb., at station No. 2, and 148 million foot-lb. at station No. 8. In lest (5) the engine- duty was nearly 142 million foot-lb. at station No. 2, and nearly 143 million foot- lb. at station No. 8. In test (c) the capacity of pumps per diem was found to be 6,093,000 gallons at station No. 2, and 6,177,000 at station No. 8. In each case, therefore, the results attained were well over those contracted for.

Pumping and Service Reservoirs, Reticulation, etc. — The reservoirs provided are intended for three different uses, namely, to act as receiving and suction- tanks, to regulate flow in the main, and for service i)uri)oses. ddiere are seven suc tion-tanks, namely, one at each pumping-station exce])t the tii‘st, the pumps of which draw from the storage-reservoir at Mundaring. Of the seven all but one are concrete- lined tanks, the exception is the large 10-million-gallon reservoir at mile 77, which was built some years previously for railway purposes, and was taken over, as it is large enough to furnish a substantial reserve in case of accidents to the main or other works in the preceding portion of the scheme. The reguhiting tanks, two in number, are also concrete-lined, and are much the same in design as, although smaller than, the receiving and suction-tanks. That at Baker’s Hill (mile 24) re gulates the flow at what is (allowing for friction) the highest ])oint on the long and irregular section between pumping-stations 2 and 3; and the tank at West Northam (mile 36) not only reduces the extreme possible pressure on the pipes in the Avon valley by 100 feet, but also permits of regulation of the flow in such manner as to keep the pressures at a minimum in regular working. The service reservoirs are three in number, namely, one of 1 million gallons at Coolgardie, one of 2 million gallons at Kalgoorlie, and the large one at Bulla Bulling. The two smaller reservoirs are con crete-lined, and otherwise much the same as the receiving and suction-tanks above

WEST AUSTLiALIAN MINING PRACTICF]

mentioned, being also provided with by-passes, so that in case of accident or necessary cleaning the working of the scheme need not l)e interrupted.

The main distributing-reservoir at Bulla Bulling, which has a capacity of 12 million gallons, with an available depth of 20 feet, is rectangular in shape, two of the sides having slopes of 1 to 1 for the full depth of the reservoir, while the other two sides are vertical for a water depth of 8 feet from the top and then slope to the bottom of the reservoir. The vertical portion or wall, rests on a bench 6 feet wide, from the inner edge of winch the sloping lining is carried down to the bottom of the reservoir. The material of the reservoir-basin consists of ijidnrated clay, iron stone conglomerate, and bands of limestone, the whole being badly fissured and per vious to water, and liable to disintegration and to slides due to greasy backs. The author’s experience of concrete-lined reservoirs on the West Australian goldfields had been such as to show conclusively that concrete-lining, even 2 feet thick, would crack when exposed to the sun; and, moreover, the cost of thick lining in a reservoir of this size wmnki have been excessive. It was, therefore, determined to limit the thickness of lining to 12 inches, and to provide joints in the concrete to take the inevitable movements due to expansion and contraction.

The concrete used in lining both floors and walls was composed of 5 parts of machine-broken granite, the stones being of a maximum size of 2 inches, 2i/2 parts of sand, and 1 part cement; all measured by bulk. What is commonly considered the only good class of sand was not obtainable nearer than 4U miles from the work, and the cost of carriage would have been heavy; but only 1 mile away there was found a very fine sand, containing 5 per cent, of clay, and 15 per cent, of very fine powdery silica, easily movable on washing. The loam, combined with tlie extreme fineness of the sand (only 2 per cent, being retained on a 250-mesh sieve, and SW per cent, on a 400-mesh), did not at first promise good results, Imt the mortar tests proved very satisfactory, and in fact the bricpiettes made with this sand (Table III.) proved stronger than those made with the standard sand, which was clean, coarse, and sharp; the cement used for both sets of briquettes was taken from the same cask. It is generally considered that loam or clay is always injurious to cement mortars, but the results obtained in this instance throw doul)t on the ))oint, and confirm those obtained by Professor C. E. Sherman,*") of the Ohio State University, which showed that in practically every case the substitution of loam and clay for a corresponding (luantity of sand increased the strength of the mortar.

The floor of the reservoir, 12 inches thick, was put down in two layers, the first or bottom layer being 8 inches, and the top layer 4 inches thick. In the centre of the bottom layer, a grillage of barbed wire, spaced 12 inches apart, was put in for the purpose of adding tenacity to the concrete, and thus giving it greater power to resist cracking under contraction. The upper surface of the bottom portion of the floor was purposely left smooth, so as to allow the upper layer to slide thereon. By this arrangement the top portion acts as a false floor, and any temperature cracks are not so liable to continue into and through the l)ottom portion as would be the case with the floor built in one layer. At the junction of the floor and sides a bitu-

('0“ Effect of Clay and Loam on Cement Mortar.” Eiigiiwii nig .Vews, Vol. I. (1903), page 443.

Wat1]K Supply

ininous joint, (i inches deep by V2 inch wide, is provided. The sides and walls are also reinforced with barbed wires running horizontally and placed 9 inches apart. The sides and walls were built in sections with a hituniinous joint between each pair. This arrangement effectually confined the results of contraction to the joints themselves, nearly every joint opening more or less at the faces, while the remainder of the lining remained intact. Soon after first filling, the reservoir, much of which was Imilt in intense summer heat, was found to he leaking at the rate of in. in vertical depth ])er diem; Imt instead of being spread in irregular cracks all over the reservoir, the leaks weie confined to the Hues on which the above-mentioned joints occurred; they were easily located, and were effectually stopped by cutting out por tions of the joints to .a depth of '2 or 3 inches, caulking with oakum, and facing with bitumen and tar.

Reticulation. — The original scheme did not allow for any leticulation of town ships for domestic purposes, or of mining centres, it being only intended to bring the water to some high hill — for instance, Alount Burgess, a few miles north of Coolgardie — and to lay a subsidiary main thence to such situation in each town ship or mining centre as the local authority should choose for its service-reservoir. Eventually, however, the complete reticulation of the townships of Kalgoorlie, Cool gardie, Boulder, and the Kalgoorlie Mining Belt, had to he undertaken as part of the main scheme, in addition to the laying of small pipes to mining centres near Cool gardie and Kalgoorlie; but one or two of the smaller townshii)S, namely, Northam and l''outhern Ch-oss, have installed their own reticulation, purchasing water in bulk from the main scheme, and retailing it to the ratepayers.

A separate telephone-line for the works was laid down between the head office at Perth and Kalgoorlie. It is of ordinary type, with one repeating station about half-way, and was extremely useful during construction. Connection is thus secured between the head office and the pumping-stations, and, by means of field-telephones, with the maintenance gangers.

Cost of the Works. — The actual cost, including all extras, contingencies, and establishment charges, was £2,660,000, an excess of £225,000, or 9f4 per cent., on the original estimate, after deducting from the latter £65,000 for works which were allowed for therein but were not carried out. This can hardly be considered a large excess when it is remembered that the original estimate was based on tentative data prior to survey; but as a matter of fact almost the whole of the excess is accounted for by one item alone, namely, pumping plant, partly due to somewhat more water having to be pumiced, partly to the provision of more reserve ])Ower for accidents, and largely to enhanced cost per horse-power. Low-duty engines were originally allowed for at an estimated cost of £22 per horse-power, while the actual cost of thc- plaiit installed was nearly £48 per horse-power, including Federal customs duty, spares, etc. So long as the consumption of water remains much below the ultimate amount allowed for, and so long as cheap local fuel (firewood) remains available, the high-duty jhant will not prove as economical as the low-duty and cheaper plant would have been ; but the conditions will be different when the full consumption is reached, and utilization of the more costly fuel becomes necessary.

West Australian Mining Practice

total expenditure of £2,660,000 was sul)-(Iivided as follows; —

£

Storage reservoir, including 6 miles of railway line, land compensation and river-training works (capacity of reservoir being 4,600 million gallons, the cost is £61 per million gallons of storage) . . , . ... ... 280,000

Service and break-pressure reservoirs of a total capacity of 16 million gallons

(£3| per 1,000 gallons) ... . . ... . ... . . ... 60,000

Conduit 352 miles long, including all valves and specials (£5,312 per mile) 1,870,000 Pumping machinery, including erection, freight. Federal customs duty and

spares (nearly £48 per horse-power) . ... ... ... ... 290,000

Pumping stations, exclusive of machinery but including the buildings, em- plojees’ quarters, suction-tanks, railway-sidings, coal-staithes, and stores (£23 per horse-power) ... ... ... . . ... 140,000

'felephone line and other contingencies . ... ... ... . . . . 20,000

£2,660,000

'Cable I. — Analysis of Soils along Route of Main.

[ Sami>le

1 Number.

Place.

Reaction.

Moisture.

Loss on Ignition Total Organic Matter.

Total

Soluble

Matter.

Sodium

Chloride

NaCL

Carbonic

dride

Co2

Humic

.\cids.

Per

Cent.

Per

Cent.

Per

Cent.

Per

Cent.

Per

Cent.

Per

Cen,

Made September,

Hines Hill (surface)

Alkaline

Hines Hill (3 feet below surface)

13'86

Southern Cross (surface)

Southern Cross (3 feet below surface)

, ,

Nil

Boorabbin (surface)

Vcid (faint)

' 4'5

Boorabbin (3 feet below surface)

Nil

Coolgardie (surface)

Coolgardie (3 feet below surface)

,

Yellowdine (surface)

Yellowdine (3 feet below surface)

.\lkaline

I'll

lade December,

Yellowdine Salt Lake (surface) ...

Yellowdine Salt Lake (3 feet below surface)

W. C underdin Clay Pan (surface)

,

W. Cunderdin Clay Pan (3 feet below ' surface)

E. Cunderdin Sand Plain (surface)

E. Cunderdin Sand Plain (3 feet below i

Note. — Moisture estimated on soils as received. Other estimations made on water-free samples.

WxiTER SUPPLY

Table II. — Tests of Specimen Pieces of Locking-Bar Pipes.

Number of Pieces Tested.

Thickness

Weifht of Locking-Bar per

Lineal Foot.

Number of Pieces that Failed.

Average Breaking-Stress of Plate of Pieces that Failed.

of Metal in Pipe.

In the

Locking Bar.

In the Plate.

In the

Locking Bar.

In the

Plate.

Inches,

Lb.

Tons per sq. inch.

Tons per sq. inch.

26'3

r-\

—

26'8

5-16 '

8)

23'8

Table III. — Tests of Briquettes made from St.\nuard Sand and from Sand used for Bulla Bulling Reservoir Concrete.

(3 Sand to 1 Cement).

Break in

g-Stress per Square Inch.

7 Days.

28 Days.

3 Months.

6 Months.

1 Year.

Sand, as used in reservoir, )

Lb.

Lb.

Lb.

Lb.

Lb.

containing 5 per cent, j- loam ... ...)

Clean standard sand

It would be difficult to express accurately in terms of current coin the valne of the benefits wliicli have accrued to the mining industry as a result of this huge work, but some conception of the advantages derived may be gained from the fact that, Avhereas the cost of fresh water consnmed l)y the mines in the Kalgoorlie district prior to the advent of the Mnndaring Water Supply, ranged from a minimum of 25s. to a maximum of 75s. per 1,000 gallons, the general price in the same district to-day is 5s. per 1,000 gallons. Some of the mines whose ore is of “low-grade” are being sup plied with all their fresh water at 3s. 6d. per 1,000 gallons,* and a large quantity of water is purchased by several of the mines at a cost of Is. 6d. per 1,000 gallons to be used for the disposal of residues by sluicing.!")

It must be admitted that the great expansion that has taken place in the mining oi)erations on the Kalgoorlie field would not have been possible without the Mundaring water, inasmuch as the requisite supplies would not have been forthcoming from other sources; consequently the tonnage treated would have been smaller, fewer men would have been employed by the mines, the resultant profits would not have reached the present scale, and thousands of persons now more or less directly dependent on the mining industry would be without employment.

Since October 1, 1909, the prices for general and low-grade supplies have been raised to 7s. and 5s. respectively.

Wl-Sa' AUSTRAL TAN MINtKG PRACTICE

'J'he I'olloAviiig' table shows the priiu'ijnil Kals'oovlie mines in the

normal wintei' and months of dime and

Slimmer eonsiimption of the Deeemlier, 1909: —

c"

i)

u

Cj

D

i:

'I

'I

(75

U

o;

'u

c/5

'5

{/5

s

Ct

Oi

rt

o;

u

ct

rt

"c

d

c:

;3

u

o

O

c/}

Water used for sluicing away residues.

AVATKR SUl'PTA

Much has been done by the Government in the way of providing reliable inland water supplies in other and more remote districts of the goldfields outside the scope of the Mnndaring scheme. At Cue and Leonora, for instance, water supply works have been established at considerable cost, and have been banded over to local administrative boards. In other mining centres much good work has been done in the sinking of wells and the construction of dams and cement tanks in dis tricts where the natural sources of water sui)ply are unreliable.

West Australian Mining Practice

Chapter Xvii

Underground Water And Mine Drainage

The state maps delineate numerous lakes existing throughout the interior of Western Australia. Some of these are shown as covering considerable areas; they are shallow depressions containing little or no water except after heavy rains. This, however, affords only a temiiorary supply, the water quickly disapitearing, ])artly l)y ]iercolation, but chiefly l)y eva]ioration. The lake bottoms are covered with salt mud, which quickly renders the accumulated storm waters unfit for domestic use or steam boiler purposes.

The average rainfall on the goldfields is nine inches a year, and it is, therefore, not at all snrimising that no heavy flows of water have been tap])ed in the upper levels of the mines, neither have any deep-seated sources of supply been found, and tlie almost invariable experience is that, as work proceeds below that portion of the mine in which the water is found in greatest volume, the amount to be contended with steadily diminishes.

In districts in which only one mine has been develo])ed to any great depth, that mine has been found to drain the surrounding country over an extensive area and in such case a fairly large jnmiping plant becomes necessary. As an instance of this the Cosmopolitan mine, at Kookynie, may be mentioned, where a flow of upwards of 300,000 gallons ])er day has to be coped with, while the adjoining mines working at shallower depths have little or no trouble witli water. The lode in this instance is a massive quartz body, and undoubtedly acts, thronghont its great length, as a conduit for underground waters.

It is rare, however, that the quantity to l)e ])umiied from any one mine is very great, the mines in the Murchison and Eastern Goldfields being, as a rule, free from any heavy burden of expense in this direction. At Kalgoorlie many of the mines are almost free from water, so much so in some instances, as to enable the ore to l)e dry-crushed without the aid of drying appliances. While this may, to some extent, he the effect of so many mines working in close proximity, each with its own nnwatering i)lant, and, therefore, steadily draining a large area, yet the compara tive dryness of this section of country can be ganged from tlie fact that the largest quantity of Avatei' raised per day from any one mine in steady operation amounts to only 20,000 gallons — this being from the deepest sliaft on the field, that of the Creat Boulder, 2,000 feet in deiith — and varies down to, in some instances, 850 gallons imr 24 hours, tlie latter l)eing draAvn from a mine that is over 2,000 feet deep (Great Boulder PerseAmrance).

Undergkound Water Anj) Mine Drainage

Ill the majority of instances the mine water is intensely salt, and quite unfit for boiler use, though occasionally comparatively good supplies of fresh water are obtained at shallow de]iths. The subjoined analyses of Avater taken from two mines widely separated may he of interest.

Oroya Brownhill IMines (Kalgoorlie).

Salt Water from Brown Hill Shaft.

Specific Gravity

Silica Alumina and Ferric Oxide

Lime

Magnesia

Soda

Carbonic Anhydride

Sulphuric Anhydride

Chlorine

Deduct Oxygen equivalent to Chlorine

Loss of difference

Total Solids

The chief Salts probably present are therefore : —

Silica .Alumina and Ferric Oxide

Calcium Sulphate

Calcium Carbonate

Calcium Chloride... .. . .

Magnesium Chloride

Sodium Chloride ...

Weights are Grammes per litre (1 : 1000).

WE8T AUSTRALIAN IINlXd PRACTICE

25()

Northern Mines (Lawlers, Bast Murchison).

S.tMPLES T.VKEN FROM ; —

Mine Water from 170 feet Level.

Mine Water from bottom of Main Shaft.

Battery Suppl> Tank

Water from Town Well.

Specific Gravity

Logo

Degree of Hardness

J3'75

37 50°

37-50°

Weights

are Grammes

per litre ' 1

1000).

Lime

Magnesia

Soda

Carbonic .\nhydride

Sulphuric Anhydride

Chlorine

Deduct Oxygen equivalent to Chlorine

Loss or difference

Total solids

The chief salts probably present are therefore ; —

Calcium Sulphate

Calcium Carbonate

Calcium Chloride

Magnesium Chloride

0'2820

Sodium Chloride, Silica, Alumina, and Ferric Oxide

Tliougli no clescriptiou of underground practice could be considered com plete without a reference to the means adopted for un watering the various mines, it is felt that inasmuch as no very serious prohlems have presented themselves in this direction, any comprehensive description of the types of jnmips, etc., used is un necessary.

In some of the large mines, and in many of the smaller ones, bailing is re sorted to in those cases where such work does not unduly interfere with the daily su])])ly of ore to the mill. The skips used for hauling are frequenPy fitted witli a clack in the bottom; this opens inwards with the rush of water and closes tight when the skip is raised. In lioth vertical and underlay shafts, bailing tanks or skips are often used, the latter being S])ecially constructed so as to retain the maximum amount of water in travelling through an underlay shaft having a vari able inclination. The tanks or skips are emptied by means of a short arm projecting over the side and engaging with a stop placed on the head-frame in such a position

Underge0Uni3 Water And Mine Drainage

that when the discharge door of the skip is opposite to or immediately over the launder leading to the surface storage tank, a chain, one end of which is attached to the discharge door and the other to a bar connected with the arm mentioned, pulls open the door and allows the water to escape.

Where bailing is in vogue in some of the deeper shafts dams are cut out of the sides of the shaft or are placed in the levels and the water is drawn at regular in tervals from these into the bailing tank or skip. Thus, on the Lake View Consols mine at Kalgoorlie, where the shaft is 1,900 feet deep, dams are built at the 1,200 and 1,800 feet levels. The water above the former is collected at eacli level and drained to the cistern, while that below is run to the cistern at the 1,800 ft. level. A small pump, driven by compressed air, raises the water from the bottom or 1,900 ft. level to the cistern at the up].)er level. Eroni the cisterns, which are situated 100 feet distant from the shaft, a six-inch pipe is laid, and, by means of a valve at the outer end, the lilling of the skip is regulated.

Compared with pumping, bailing is much cheaper and possesses some additional advantages where it does not interfere with the hauling of ore; the initial cost of the appliances is less, a heavy loss in steam condensation is obviated, repairs and upkeep are much lower, and there is no danger of the unwatering plant being flooded.

Of the pumps used those of the Cornish plunger and lift type find consider able favour in many mines in which the flow of water is fairly steady and not liable to sudden increases. Among the larger mines having electric power-generating plants, the electrically driven three-throw pumps are coming more extensively into use, and are giving great satisfaction. On the Ivanhoe mine at Kalgoorlie one of these pumps is erected on the 1,000 ft. level and, pumping from there to the surface, has a capacity of 6,000 gallons per hour. The dimensions of the pump are: Rams, 5% inches diameter, 8 inch stroke, making 50 revolutions per minute. The current used is alternating three-phase and the puupi is driven by gear from a 50 h.p. motor. Capacity, 220 volts, 585 revolutions per minute.

From the foregoing observations it will be gathered that the question of mine drainage in Western Australia does not present any serious difficulties, the mines, with one or two special exceptions, being practicall} dry. The subject, therefore, has not been considered of sufficient importance to warrant more than a mere general reference.

Wet Australian Mining Practk212

CHAPTER XVm

Wages, Euel, Transport And Administration

Eates of Wages — Costs of Materials — Freight Eates — Mining La'.

Many and great were the difficulties that beset the development of the gold- iields of Western Australia at their inception; and though these have been modilied during tbe past 8 or 10 years, the prevailing conditions are greatly against the mine-owners. The distance by rail from the port of Fremantle to the mines referred to in this book, ranges from 387 to 561 miles, and the cost of trans- Ijort is a heavy item of expense.

The fuel used on the mines is wood obtained from belts of salmon-gum and mulga growing in the district. In some instances this is cut and conveyed a dis tance of 8U or more miles. Coal is obtainable from the Eastern States and from West Australian collieries, and it is used in small (piantities for })arlicular purposes only. Mining timber is obtained fi'om the same source as the lirewood, but much of the best timber has to be brought from greater distances.

In the matter of wages, the mines of Western .Vustralia pay much higher rates than any other Australian held, and are exceeded only in a few instances in one or two other parts of the world. The hours of laliour per day are hxed by Act of Parliament at eight, and three shifts are worked on six days of the week; the exact working hours are shown further on.

In the face of so many disabilities to the development of mining, the mana gers have naturally used every endeavour to adopt machinery of the most modern and complete description, and to practise the strictest econoni)' in every dejiart- ment of mining and treatment.

The result has been shown in the foregoing pages, Imt for the sake of easy reference, some further information has been added, in tabular form, at the end of this chapter.

Administration and General. — The mines referred to in the foregoing pages are owned by Limited Liability Companies having their head offices in London. In Western Austi-alia each company is represented by an Attorney and a General Manager. In some instances tlie general management de'olves upon one man only and in others is controlled by linns of Mining Engineers, Imt in either case the General Manager is solely resi)onsible to the Directors, in London, for the conduct of the Company’s affairs in AYestern Australia. To the General Manager falls the task of appointing his staff on the mine — Aline Alanager, Aletallurgist, Engineer, Accountant, etc., each having control, under the General Alanager, of his particular department.

Avagps, Transport And Administration

Under the State Law it is compulsory to maintain a share register for any Oompany doing business in the State. Tliis is kept either at the mine office, or at tlie office of some accountants in the nearest town, as may he considered most con venient to the local shareholders.

The progress and result of all work on the mine is published at intervals of two or four weeks, and so supplied to the newspapers foi‘ general information at about the time at which it should have reached the London ffffice. Information in re lation to important developments, etc., despatched by cable to the London office, is usually made pul)lic locally within 48 hours of its despatch.

Fig'. 109. Ore Transportation.

Tramway feeding the central mill with ore from the Northern Mines at Lawlers (85 miles distant from the Government Railway system, and 633 miles from Fremantle).

The system of account-keeping has been brought to a high degree of per fection. By the methods adopted the mine-otviiers are enabled to see, not alone the gross income and expenditure relating to their pro])erty, but also the cost in detail of each of the many branches of mine expenditure. These costs deal only with actual mining expenditure in AA'estern Australia. Affiriations in the methods of cost segre gation exist amongst the various Companies, each one having a system adapted to its own particular requirements; but in all the two main factors — income and ex penditure — are clearly stated month by month.

\V1]St Australian Mining Practice

The ground comprising the area of the mines is Crown Lands, held by the Companies under lease for a term of 21 years. The lessee is subject to an annual rent of twenty shillings ])er acre i)ayal)le to the State Government, and to the con tinuous em])loyment of one man for every six acres of ground or fraction thereof contained within the lease or leases. The boundaries of the leases are fixed by survey made by a surveyor holding a licence from the Crovernment ; boundary lines are taken to continue vertically to an unlimited depth, and the lessee’s right to work any lode or ore-body of any descri])tioin ceases as soon as such ore-body inisses beyond the defined boundaries of the lease. The area of any one

Fig'. 110. A Mode of Transporting' Stores from the Railway to Lawlers.

gold-mining lease is limited to 24 acres; but any person or persons other than Asiatic or African aliens can apply for, and olfiain, as many of these areas as may he desired, or that may lie availalfie in the locality. In cases where two or more leases adjoin, an amalgamation may be efl'ected, but the aggregate of such amalga mation is limited to 96 acres on the strike of the lode. Under amalgamation the labour i-equired to man each lease may lie concentrated at any ])oint within the 96 acres. The lessee’s title to the ground for mining pui'i)oses is unassailable so long as the labour conditious are observed and the annual rent is ])aid in advance. Failure to ol)serve these ])articulars renders the lease liable to forfeiture to the Crown. The landlord is represented by the Minister for Mines of Western Australia, and all

Fuel, Transport And Administration

work in connection with the mines is, to a very great extent, regulated by a numi)er of Acts of Parliament and Regulations relating thereto. In the more important mining centres Wardens are appointed to hold courts, at which any matter I'elat- ing particularly to mining is dealt with.

in connection with the ]jractical working of the mines the (lovernment ap point officers to see that the various Acts and Regulations are complied with. In spectors of Mines deal with all matters relating to work underground; Inspectors of Machinery deal with the whole plant on the surface and Inspectors of Boilers with the cleaning and testing of Imilers at regular intervals throughout tlie year.

TABLP; i.

Hates or Wauks.

Class of Labour.

Kaljioorlie

District.

Leonora

District.

Ciie-Dai I-)a\vn District.

Rock-drill men in sliafts

14/4

15/-

H/-

rises

13/10

14/6

14/6

,, ,, ,, all other parts of the mine

13/4

14/-

13/4

Hammer-and-drill men in shafts, winzes, rises and all parts

11/8

1 3/4

12/6

Hracemen and platmen

n/s

12/4

12/-

Mullockers, shovellers, truckers, and tool carriers, underground...

1 1 /6

1 1 /4

Men working in cyanide vats and on filter presses

11/8

12/4

12/-

Timbermen

13/4

14/-

13/4

Surface labourers (the term "surface labourers" includes pick-and-shovel men, sailor gang, lumpers, battery feeders, slimes, sand and wood truckers, wood trimmers, and general labourersl ...

10/-

11/-

10/10

Boiler cleaners

10/-

12/6

12/6

Horse drivers

11/8

11/-

10/10

leeding and grooming

11/8

12/-

11/10

Drill and tool sharpeners

13/4

13/4

13/9

Kngine-drivers, first class

1 4/-

15/9

15/-

,. second class

13/4

14/6

13/4

Firemen ... ... ... ... j

1 1/8

1 1/8

13/6

Blacksmiths

13/- to 15/-

16/8

15/-

(.'.arpenters ... ... ... ... . i

15/

16/8

15/'-

Fitters ... ... ... ... i

13,< - to . 15/-

16/8

1 5i'

Surface . The week s work consists of 48 hours men working shifts inclusive, and those working day shift only, exclusive of crib time. Underground : 47 hours, inclusive of crib time.

2G2

WEtSl’ AUSTRALIAN MINING PRACTICE

Table Ii.

Firewood, Round and Sawn 'Pimber, and Water.

Kalgoorlie

District,

Leonora

District.

Cue-Day Dawn District.

Firewood, per ton of 2,240 lb

13/-

13/-

18/6

Water, fresh, per 1,000 gallons

Ur)5/-. 3/6, 1/6

Ibi 5/6 & 3/6

{b) 8/6 & 3/6

Mining timber, 6 inches up to 20 inches at small end, per running foot

3d. to 2/-

4id. to 2/8

1/- to 3/4

Sawn timber, Australian hardwood, per 100 super, feet

18/- to 20/-

20/6

,20/-

,, ,, Oregon

28/- to 30/-

32/6

32/-

(a) Normal price, 5/-. Price paid by “ low grade" mines, 3/6. Slucing water, 1/6.

(b) Price adjusted according to volume of consumption

Table Iii.

Railway Freight Rates.

From Fremantle ..

Kalgoorlie

District.

387 miles.

Leonora

District.

548 miles.

Cue-Day Dawn District.

561 miles.

Per ton

Per ton

Per ton

£

s.

d.

s.

d.

£

s.

d.

Boilers ...

Cyanide

Dynamite

Iron and Steel

, , , , bar and rod

,, galvanised

,, pipes under 4 inches

12 inches

Machinery

Timber, Australian hardwood ...

imported

Zinc shavings

AVACJKvS, FUEL, TKAN.sroirr AND ADMINISTRATION

TAISI.I-: i\.

XUMliKli OF -AJkX EmIM.OYIOI), 'rONNA(;i': CkUSHKI), V'aLUK of iy’liOJlL'CTJO.X. AM) Dividknos I’AIJ).

No.

Mine.

Locality,

Number of Men Employed at 31st December. 190Q.

Tonnage Crushed to 31st December,

Value of Production to 31st December,

Dividends Paid to

31st December.

(Ireat Boulder Proprietarv

Kalgoorlie

(Ton 2, (XX) lb.) 1,569,295

£

6,750,247

£

3,169,300

o

Great Boulder Perseverance

1,616,622

4,733,265

1,426,250

Oroya Brownliill

978,928

4,623,442

2,146,241

Associated

1 ,004,699

2,846.826

691,449

Kalgurli

766,015

2,346,852

907,500

South Kalgurli

531,658

995,353

85,000

I van hoe

.

1,898,679

5,723,780

2,348,750

Golden Horse-Shoe

2,132,743

7,304,276

3,000,000

Lake View Consols

1,266,264

4,200,716

1,431,250

Sons of Gwalia

Leonora

1,270,276

2,608,712

580,051

(ireat Fingall Consolidated

Cue

1,491,839

4.036,707

1,696,875

14,527,018

/46, 170, 176

17, 482, 666

ixi)j:x

Page

Administration and General

Air Compressors

,, Hoist

Amphibolites, Fine Grained

2, 5

,, Coarse Grained

— . 1

„ Acid

11, 13

Analysis of Salt Water

255, 25G

Ancient Sediments

Associated

. . 193,

199, 263

BlNDULl

3, 9

Broken Rock, Removal of . .

25, 34

Boorara (Waterfall)

Bores, Deflection of

Boring and Firing . .

,, Out Shaft Bottoms

25, 26

Boulder Belt

1, 7

Boulder Block

Box, Rise

,, System

. . 35, -13, 47, 4-;

,, System (Spaced), Shaft Timbering

Bucket and Traveller used in Shaft

Sinking . .

Buckets, Side Tipping

Button 's Quarr.v

Cage Chairs and Bearers

Guides

43, 44

,, Indicators

1S3

Cages

Calc-Schists

4, 11, 13

,, Deposits in the

Call Bell System . .

Cap and Post Sets, Framed or

. . 120,

121, 122

Carbonated or Schistose Ore Bodies

Cassidy Hill

‘ ‘ Chinaman ’ ’ Chute

128, 130

Chutes

Crosscuts and Drives

Crosscutting

Coach Screws

Coarse-Grained Amphibolites

2, 7

Code Signal

Coke Furnace

Comparative Cost of Shaft Sinking

Compressors, Air

Conglomerates

Construction of Pent House . .

Consumption of Water

Coolgardie

Page

(iores (Diamond Drill)

Costs, Development

Cost, Diamond Drilling

Cost of Fuel

. . 258, 262

Costs of Materials

Cost of Sinking Shafts . . 25, 31,

53, 57, 59, 67, 68

„ of Sinking Underlay or Incline

Shafts 59, 67, 68

,, of Rising-

Costs, Sloping . . . . 147, 150,

151, 152, 154, 155

of Winzing

. . 113, 114

(Water Supj)!}')

. . 227, 249

Cut, Centre

25, 29, 30

,, Stojie

25, 26, 28

,, Y-Shaped

Day Dawn, Geology of , ,

. . 1, 22

Deflection of Bores

Description of Stage

25, 50

Deposits in the Acid Amphibolites

,, ,, Calc-Schists

,, Ore

. . 10, 22

,, Recent

2, 10

Diabases, Quartz

. . 2, 5, 11

Diamond Drilling

Dimensions of Drives and Crosscuts

Direct Hoisting in Shaft Sinking

Distance between Levels

Dividends Paid

Double Track in Level

Drainage, Mine

Drill Sharpening, etc.

Drives and Crosscuts, Dimensions of

Ed-wards Shaft

. . 15, 70

Electric Signalling

. . 191, 193

End and Wall Plates

Explosives . . . . 25, 31,

.33, 207, 208, 210

,, and Firing-

. . 25, 31

Composition of

, , 208, 210, 220

Examination

,, Importations

„ Purity

,, Used in Three Com]-avtmeni

A'ertical

Shafts

Fair Play and Devon Consols

S

Faults

2G5

I X L) Ex

Page

Felspar aiicl Quartz Porphyries . .

2, 9

Flat Back Stopes, ore-pass

Fine-Grained Amphibolites

2, 5

Firewood, Cost of

Firing and Explosives

. . 2.5, 31

Firing Holes

Fish Kock

Framed or Post and Oa]i Sets

. . 120, 121, 122

Fi-ame or Sipiare System

. . 25, 50, 52, 5S

Framed Set, Ore Chute

l'’reight .Rates

Fuel, Cost of

. . 258, 262

Fumes

I'hise, Safety

. . 2(17, 216

Gate for Changing Cages

Iso

Geological Sketch Map, Index to..

Geology

1, 21

„ of Day Dawn

1 , 22

General

,, of Kalgoorlie

1,2

,, of Leonora

1, 21

Gnumlialla

Golden Horse-Shoe

. . 15, 263

Golden Ridge (Waterfall)

Go\’ermnent Water Supply

Granite Rocks

Great Boulder Perseverance

. . 118, 199, 263

Great Boulder Proprietary

15, 199, 263

Great Fingall . . . . . . 23

66, 188, 201, 263

Greenstones

2, 21

,, Later nr Intrusive . .

O

Older

'2

Grits

O

Guides, Cage

Hannans Lake

1, 7, 8, 9

„ Hill .

7, 14

,, Reward

. . 13, 14

Head Frames

. . 70, 72, 74, 75

Hidden Secret

Hinged Shoes for Cages

Hoist (Air)

Hoisting Direct in Shaft Sinking

Ore .

,, Rojies

Holes for Firing

Houses, Pent . . . . . . 25,

38, 39, 41, 42, 44

Pent, showing Slight Variation

in Detail

of Construction . .

,, Pent, with Ventilation Flue and Sal'ety

Door

Index to Leases

Incline or underlay Shafts 59, Gl,

62, 64, 67, 68, 69

,, ,, ,, Cost of

Sinking 59, (i7, 68

„ „ „ Sizes of

,, „ ,, Three Compartment G2, G8

Inter-Ijevel Signals

Page

Intinsive or Ijater Greenstones

Ivanlioe

. . 199, 263

IciNT.s and Wedges, Shaft Timbering

,, (Water Supply)

Kaia;cjcrlje, General Topography of . .

Geology of

1, 2

Kalgurll

. . 199, 263

Kanowna

Kibble, Self-Ti]>|iing

Knocker Line

18,5

Knrranii.a

Lake Bailee

,, Carey

Raeside . . . .

.. View Consols

118, 200, 263

Later or Intrusive Greenstones . .

Laterite

Ijaw, Mining-

Leading Stopes

l/eases. Index to . .

Leonora, Geology of

1, 21

Topography of

Levels, Timbering of

. . 118, 120

Loam

Maciijnery, Pumping (Water Supply)

Maritana Hill

Materials, Cost of

Men Employed

Method of Wedging Cage Guides, Shaft

Tim-

Iiering

Mine Development

., Drainage

Mining Law

Monument Hill

Mt. Gledden . . ...

Mt. Hunt

. . 1, 7, 14

Mt. Squires

Mnndaring Weir

. . 229, 246

Older Greenstones

Ore Bins

. . 160, 163

,, Bodies, Schistose nr Carbonated . .

,, Bodies, Quartzose

., Chutes and Passes

,, Deposits

10, 22

Hoisting

,, Samiiling

Slioot

Tippler

Transportation

. . 161, 258

Oroya Brownhill

(liute

Passes

Pent House . . . . 25, 38, 39,

41, 42, 43, 44

Lnuex

Pent House, showing Slight Variation in Detail of (lonstrnction „ Houses witli Ventilation hhiie and Safety Door

Pig Stys .

Pipe Line (Water SujJply)

Plat Ore Bins Plates

„ End and Wall . .

Peridotites Pole Lagging Porijhyrites

Porphyries (Quartz and Felspar)

Position of Holes in Vertical Shalt Post and Cap Sets, Framed or ., and Stull Timbering- Production, Value of Pimiiring Machinery (Water Supply)

Page

Page

Shafts, Cost of Sinking Underlay or Incline 59, 67,68

49, 98, 160 2, 1

2, 8 2, 9

121, 122

227, 244, 247

120,

Quartz and Felspar Por[)hyries Quartzose Ore Bodies

Hates of Vages Hallway Hates Heeent Deposits Hemoval of Broken Hock Heservoirs, Heticulation, etc. Hill Stoping

,, Stopes, Ore Passes Hises and Winzes Hising, Cost of Hock, Broken, Hemoval of „ Drilling Machines Hocks, Granitic Hopes (Winding)

SADDLE-Back Timbering Safety Catches

,, Detaching Hooks

„ Door and N'entilation Flue. Pent

with „ Fuse Sampling Sands

House

2, 9

258, 261 258, 262 2, 10 25, 34 227, 247 150, 156 115, 117 25, 34

1()8

207, 216

,, Sizes of

„ Underlay

„ Vertical

„ \'ertical. Three Compartments

„ Vertical, Three Compartments

sives used in Slioes (for Cages)

Sliriiikage Stoping Side-Tipping Buckets Signal Code . .

Signalling . .

Single-Drum Hoisting Winch Sinking- of Shafts 25, 26,

25, 59, 61 . . 62, 93

25, 32, 33, 93 . . 33, 61

Explo-

. . 152, 157

4: / j 0 ‘Sj

57, 59,

61,

67,

53, 57,

59, 67,

Shaft, Cost of . . of Three Comjiartment Vertical Shatts Underlay or Incline Shaft Underlay or Incline Shatts, Cost of . .

59, 61 67, 68

Sizes of Compartments, Three Comijartment Vertical Shatts ., of Shafts

„ of Underlay or Incline Shafts

Skips Slates

Solid Chock Method Somerville . .

Sous of Gwalia South Kalgurli Spaced-Box Shalt Timber Spaced Box System of Shaft Sinkiug Scpiare or Frame System Stage, Description of Steel Head Frames Stopes Stoj)e-Cut Stopes, Leading

„ Advantages and

„ Costs

„ Flat Back

Stoping, Methods „ Hill

„ Shrinkage

lUg

. 119, 136, 1

Disadvantages

33, 61 25, 59, 61 . 59, 61

163, 176, 181 o

22, 62, 87, 263

50, 52, 58 25, 50 70, 71 50, 152, 156, 157 25, 26, 28, 30

150, 152, 154, 155 . 142, 156

. 150, 156 . 152, 157

25,

Sandstones

„ Pig Stys .

Sanitation (Underground)

Stull and Post Timbering

Schists, Calc

2, 4, 11

„ Timbers

123, 124, 130

Schistose or Carbonated Ore Bodi

ss

Sullivan Diamond Drill

Screws, Coach

Sediments, Ancient

Three Compartment Underlay Shafts

. . 62, 68

Self-Dumping Skijrs

„ „ Vertical Shafts

Self-Tipping Kibble

Timber, Cost of

Shaft Bottoms, Boring- Out

Timbering and Sinking of Shafts

25, 59

„ Cost of Sinking

25,

31,

53, 57, 59, 67,

„ Levels

118, 120, 123

,, Measurements

„ Shaft 25, 35, 40, 47, 48,

49, 50, 52, 54

„ Sinking 25, 26, 33,

37,

J

53, 59, 61, 67,

55, 58, 59, 64

„ Sinking and Timbering

. . 25, 26, 33,

„ Stopes

. . 145, 151

„ Timbering 25, 26, 35,

36,

40,

47, 48, 49, 50,

‘ ‘ Tippler, ’ ’ Ore

54, 55, 58,

Tonnage crushed

Page

Topograjjhy of Ivalgoorlie (General) . . . . 1

„ of Leonora . . . . . . . . 21

Track (double) in Level . . . . . . . . 122

Transportation . . . . . . . . . . 161, 258

Traveller and Bucket used in Shaft Sinking . . 46

Truck Eoads . . . . . . . . . . 160

Trucking Ore . . . . . . . . . . 160

Trucks . . . . . . . . . . . . 160

Turn in Shaft from Vertical to Underlay . . 69

Underground Water and Mine Drainage Underlay or Incline Shafts 59, 61, 62, 64, 67, ,. ,, ,. Cost of Sinking 59,

„ ,, Sizes of

Shafts, Three Compartment Shaft. Timbeis

68, 69 67, 68 59, 61 62, 68

Valuation (samples) . . . . . . . . 197

Ventilation Blue and Safety Door, Pent House

n-ith . 41

Ventilation (underground) . . . . . 110, 225

Vertical Shafts . . . . . . . . 25, 32, 33, 69

„ Three Compartments . . 33

„ Three Compartments, Exirlo-

sives used in . . . . 33

Page

Vertical Shafts, Tliree Compartments, Sinking of

O O

Oo

V-Shaped Cuts

Wages, Eates of

258,

Wall and End Plates

IV alshe "s Quarry

IVarburton Eange District

Water Consumption

„ Cost of

,, Sujrplies

227,

,, (underground)

Waterfall (Boorara)

Wedging Cage Guides, Method of. Shaft Tim bering-

Wedges and Joints, Shaft Timbering . .

Weighing (samples)

Weir, Mundaring (construction)

White Cliffs Quarry

Winch, Hoisting (Single Drum)

Winding Engines

Winzes and Eises

Wollabar

Wooden Head Frames

Al)An']R/riSEMP]Nl’S

xvri

FORWOOD, DOWN & Co. Limited,

:: Manufacturing Engineers, ::

Mining And General Machinery

of every description manufactured.

SPARES FOR PANS, FURNACES, PUMPS, ETC., carried in Stock at Kalgoorlie.

Adelaide, S.A. :: Kalgoorlie, W.A.

Specialities :

Stamp Batteries. Patent Grinding and Amalgamating Pans. Pumps for Tailings, Slimes, Water. Boilers, Roasting Furnaces. Cyanide Plants.

SOLE AGENTS in W.A. for

Samuel Osborn & Co. Ltd.

(Clyde Steel Works, Sheffield),

M.vnufactures of Tool Steel, Steel Castings, Forgings, Etc., Etc.,

of every description.

Fraser & Chalmers Ltd.,

- London, England. - -

Engineers And Manufacturers Of Machinery For All Mining Purposes

Corliss Engines. Winding Engines.

Stamp Mills. Compressors.

Boilers. Riedler Pumps.

Rateau Steam Turbines. Huntington Mills.

Sole Manufacturers for THE WHITMORE BRAKE ENOINE and PATENT OVERWIND PREVENTION GEAR. ROBINS CONVEYING BELT COY., Etc., Etc.

Equitable Buildings, MELBDURNE, ViC. MACDONALD ST., KALGOORLIE, W.A.

Adaertisrmf.Nts

LfDIIDD’Q mining

W Machinery

JAW BREAKERS. ROTARY CRUSHERS. STAMP BATTERIES. ROLLER MILLS. CHILIAN MILLS.

BALL MILLS with continuous feed and discharge for DRY and WET Grinding Ores of any hardness.

Over 4,200 sold. Any capacity up to 200 tons per day,

Jigs. Oscillating Tables. Classifiers, Clean-Up Plant.

TUBE MILLS for fine grinding ores previously crushed in Ball Mills or Stamper Batteries. No sieves required.

Noyes

Bros.

(Melbourne)

Propy. Ltd. Perth.

Sole

Agents.

Noyes

Bros.

(Melbourne)

Propy. Ltd. Perth.

Sole

Agents.

J

Sulphuric Acid Pure Acid

90 Per Cent. (Commercial).

For Laboratory & Accumulators.

Obtainable In Any Quantities From The Manufacturers,

The London & Hamburg Gold Recovery

Coy. (1905) Ltd.

CHEMICAL WORKS, KAMBALLIE . Only Postal Address i BROWNHILL.

Stocks Also Held By

H. ROCKLIFFE & CO,, MENZIES & KOOKYNIE. SYD. F. BRIDGE & CO., LTD., LEONORA. McKenzie & co., limited. j. w, fimister & co,

Advertisrmf.Nts

Imperial

Electric & Engineering Coy.

(Couche, Calder & Coy.)

129 St. George’S

Sole Agents In W.A. For

Allcemeine Electric Co. (A.E.C.)

Steam Turbines, Generators, Motors, Hoists, Locomotives. Switchboards, Cables, Transformers, Boosters, Batteries, Arc Lamps, Metallic & Carbon Incandescent Lamps, Meters, Testing Instruments, Electric Accessories.

W. H. Allen Son & Co.

High Speed Engines, Condensing Plants, Centri fugal & Turbine High Lift Pumps.

L. M. Ericsson & Coy.,

Terrace, Perth,

Joseph Evans & Sons.

Steam and Power Pumps.

Arthur Koppel

Battery Shoes and Dies.

A. Ransome & Co.

Saw Mill and Wood Working Machinery.

Ruston, Proctor & Co.

Suction Gas Plants, Slow Speed Engines, Winding Engines, Traction Engines, Oil and Gasoline Engines, etc.

Telephones and Telephone Accessories.

“Vulcan” Lubricating Oiis and Greases. Baiata Belting. Asbestos Steam Pipe Covering. Wood Pulleys. Hand Power Rock Drills. Aerial Tramways. Etc., etc.

NOBEL’S Explosives Coy. Ltd.

(OlLi-A.SOO'W),

- Manufacturers Of - -

GELIGNITE, GELATINE - DYNAMITE, BLASTING GELATINE, DETONATORS, “THISTLE” BRAND BLUE FUSE, Appliances for Electrical Blasting, SPORTING POWDERS & AMMUNITION

3VX .A. Gr Z I N E: S ON A.’L.Tj, C3- O D F Z E3 la S . -

Sole Agents For West Australia!

ELDER, SHENTON & CO. LTD. Perth.

Advf.Rttsements

Marker & Gray,

Importers And Agents,

:: KALGOORLIE and PERTH I!

Representing

Edgar Allen & Co., Ltd., imperial steel works, Sheffield, eng.

For all Wearing Parts of ROCK CRUSHING MACHINERY, BALL MILLS, POINTS, CROSSINGS, Etc.

MIDVALE STEEL CO., (Philadelphia, U.S.A.)

LOCOMOTIVE TYRES and AXLES. STEEL TYRED WHEELS. ROLLEO STEEL WHEELS.

Rolled Steel Pressed Wheels, Weldless Rolled Steel Shells and Tyres and Ole Rings for Chilian, Griffin and Huntington Mills.

Neptune Manufacturing Co.

(Manchester),

“Neptune” Balata Belting

For DRIVING and CONVEYOR PURPOSES.

GLACIER ANTI-FRICTION METAL CO. londo..,

HIGH-SPEED and HEAVY PRESSURE MACHINERY

A1)\1]Ktisements

Ingersoll-Rand Go.

Air Compressors

You Cannot Get Compressed Air Cheap From A Cheap Air Compressor !

Class “P.E.” Compressor,

Electrically' driven with Motor mounted on shaft.

Are you ready for a quotation on a cost reducing Ingersoll-Rand Compressor — in

an}- size — of any type — for any service ?

We built the first successful Rock Drill in 1871, and when you buy an Ingersoll Drill to-day, you buy a machine embodying the best features and the complete knowledge of Rock Drill History. The little extra price you pay for an Ingersoll Drill is simply an insurance premium against break-down losses.

We have been building Air Compressors and Rock Drills for just on 40 years, with the mining centres of the world for a market.

Ingersoll-Rand Company,

90 Egan Street, Kalgoorlie. 41 Queen Street, Melbourne.

Adertisements

£50,000 Bonus..

If you wish to participate in the OIL BONUS promised by ih Federal Govt., prospect your Oil Leases with the

Diamond..

Core Drill

Goldfields Diamond Drilling Co. —

If you uani information about Drills and Drill ing, write to our ne.irest Office,

We are finding gold right through this potato patch.

1910 Diary

The more we develop the better she gels.

Australia Is Alright.

A

Agents for

The “Sullivan” Machinery Company

Kalgoorlie, W.A.

339 Collins Street, Melbourne, Vic. 79 Pitt St., Sydney, New South Wales Patterson Street - Launceston, Tasmania 148 Albert Street - - Brisbane, Queensland

‘An Eagle On A Globe’

For MINERS' DRILLS and All ENGINEERS’ TOOLS. BATTERY SPARES,

Shafting . .

'Phones;

Kalgoorlie 484 Fremantle 85

Etc.

Largest And ...Best Assorted Stocks In The State

46 BOULDER ROAD. KALGOORLIE and 48 CLIFF STREET, FREMANTLE.

Tbaoe Mark. Trad: Mark.

Capitau

.Vdvertisements

J. & W. Paxton,

Diamond Drilling Contractors,

Engineers and Machinery Agents.

Steam, Compressed Air and Electric Power Used.

Bore Holes put in at any Angle.

Contracts undertaken in any part of Wes tern Australia.

Our Contracts for Kalgoorlie alone total over 1 40,000 ft. of Boring.

Diamond Drilling is a Cheap, Reliable, and Up-to-Date Method of Prospecting and Developing all kinds of Mines.

Office: Boulder Rd., Kalgoorlie

(Next to Strelitz Bros.)

Telephone: 229. P.O. Box: 76. Cable Address: “Paxton,” Kalgoorlie.

Strelitz Bros.

Boulder Road, Kalgoorlie,

Mercantile And Machinery Merchants.

NOBEL’S DYNAMITE CO. (Hamburg). KOPPEL’S TRUCKS.

Dehne Filter-Presses. Cradock’S Ropes. Cement.

Coke. Zinc Shavings. Crucibles, Etc., Etc.

. . . The

General Electric Engineering Go.

Electrical Engineers.

Stocks of Continuous and Alternating Motors, Watertight Bells, Cables, and Electric

Fittings of every description.

Tangye’S Suction Gas Engines And Pumps.

Advertisements

RRHQ Street, PERTH,

I#IiUVhj And MINES CHAMBERS, KALGOORLIE.

ENGINEERS and IMPORTERS :: of MINING MACHINERY ::

Will he h;ippy to receive enquiries and to advise clients npon any niiniii”' or engineering' inatteis, and to supply specifications, drawings and estimates for anv description of plant 01' machinery.

Western Australian Representatives of the foliowing Houses;

R. & J. DICK, Ltd.

Dick's Genuine Batata Beltiny.

SANDYCROFT FOUNDRY CO. LTD., Near Chester, Stamp Batteries, Ball Mills, Tube Mills, Cyanide Plants. Electric Motors, Cornish Lift Pumps, Etc.

GWYNNES, LTD., London,

" Invinciule " Centrifufial Pumps and Pumihiift Machinery,

HAYWARD TYLER & CO LTD., Lon DON.

— Duplex. Treble f’lunfier. Boiler-feed Sinking, and Turbo-Pumps.

Wm. J. GLOVER & CO., St. Mklens, Lancs.

Steel Wire Ropes, Makers of Glover’s Djublc Locked Wire Ropes.

Denny

LOUDON BROS., LTD., Glasgow. Machine Tools.

India Rubber, Gutta Percha and Telegraph

- Works Company, Limited. — - -

WoKKs: Sir.VEKTOWN, ItSSVX, ItNGLAXlL

Manufacturers and Suppliers of India Rubber and Electrical Goods of all kinds.

w.A. branch: 107 William Street (Comer Murray street), Perth

Advkrtisements

KALGOORLIE GOLD RECOVERY Co. Ltd

(Moss Bros.

Telephone 359. Oratava Works, KALGOORLIE.

Customs Roasting and Cyanide Works. Public Assayers & Metallurgical Engineers.

Purchasers of Crude Ores, Concentrates and Tailings, “Sulphide” or “Oxidised.”

Agents fon Edwards’ Roasting Furnaces.

Between 40 and 50 now in use on the Kalgoorlie Mines.

Sweetest Roast of any Furnace ever Erected on the Fields.

Xxvt

Codes :

A. B.C. 5th Edition. Moreing & Neal. Broomhall.

Private.

The All British Agency.

C. C. Humby & Co.,

Cables :

"HUMBY," KALGOORLIE Telephone 431 . P.O. Box 255.

Mining, Mercantile & Machinery Agents & Sharebrokers,

Palace Chambers, Kalgoorlie, W.A.

Sole W.A. Agents for the following Manufacturers—

The Austral Otis Engineering Coy., Ltd., Melbourne.

Stamper Batteries. Steam Engines. Gravel Pumps Condensers.

Air Compressors. Grinding Pans. Rock Breakers. Winding Engines.

Wilfley Concentrat ing Tables. Steam and Power Pumps.

Complete Mining Plants of every description.

Bruce, Peebles & Co., Ltd., Edinburch, Scotland.

Electrical Machiner}' and Turbo Generators. Electric Motors and Generators for all Currents,

Douclas & Crant, Kirkcaldy, Scotland.

Carels Balanced Drop Valve Engines.

Corliss Engines, Condensers, etc.

The Stockton Heath Force, Warrincton, Encland.

R, Hood, Haccie & Son Ltd., Newcastle-On-Tyne, Enc.

Wire Ropes of every description.

Small & Parkes, Manchester, Encland.

“Roko” Patent Belting.

William Griffin, Staffordshire. Encland.

"Triton" High-Class Xlining Cage Chains— each Chain with Certificate of Test.

Jens Orten-Bovinc, M.I.M.E., London.

Victoria” Turbo Pumps.

Zodel-Voith Standard Flexible Couplings.

The Drewry Car Coy. Ltd,, London.

Railway Motor Cars.

M. B. JOHN, BALLARAT, VICTORIA. Brassfounuers.

Caldwell’s Patent Forged Steel Shovels.

Engineers’ Fittings, and all classes of Valves, Cocks, etc.

STOCKS IN KALGOORLIE of Wilfley Spares, Pumps, Shovels, Belting, Pulley Blocks, Geipel Steam Traps. Cornell's Patent Lubricating Air- Cocks, Cage Chains, Engine Indicators, Indicator Cards, “Plymel” Rust and Acid Proof Enamel.

ELECTRICAL MATERIAL— Lamps, Fans, Irons and all Fittings.

p)ROB.yBL\ the most important discovery made in recent ears in regard to the production of Power is that of Suction Gas. We do riot exaggerate Suction Gas has revolutionised manufacturing generalb'. Many concerns, at one time not pa\ ing owing to the great cost of producing Power by Steam or Electricity are now, by the introduction of a Hornsby Gas Plant, profitable businesses. Practical Demonstration is of far greater value than written descri[)tion. We urge anyone recjuirin.g motive Power to communi cate with us. and put our claim to actual test. We shall he tible to tlemonstrate that The Hornsby Suction Gas Plant is an unqualified success, and undouhtedlv the best on the market.

Sole

Agents:

Geo. P. Harris, Scarfe & Co.,

Murray Street, Perth,

AND AT FREMANTLE and KALGOORLIE.

For All Industrial Purposes.

Comparative Annual Cost of Fuel, etc., for Energy.

Worth Careful Study.

Hornsby Suction Gas Plants

NO LEAKAGE, NO DANGER OF EXPLOSION. NO SMELL. NO SMOKE. IS STARTED QUICKLY. ABSOLUTELY RE- RELIABLE. VERY SIMPLE. GIVES NO TROUBLE,

25 B.H.B. 100 B.H.P.

1. Electric Motor at

2d. per B.T.U. ...

£418

£1.672

2. Steam Engine, condensing (cost water & coal only)

3. Gas Engine, with Tt. on Gas at 3s. per 1000 cub. ft.

1 Hornsby Gas En gine and Suction Gas Plant

(Coke at 20s. per ten).

Saves Its Cost On First Two Years Work.

Xxvti

Advertisements

Dunlop Rubber Goods

Made In Australia.

We Supply DUNLOP Rubber Goods to all the Leading Mines in Australia.

Dunlop Rubber And Balata Beltinc.

Dunlop Engineering Sundries.

Dunlop Delivery Hose.

We Invite Correspondence.

Illustrated Catalogues Sent Free On Application,

Dunlop Rubber Co.

Australasia Ltd.=

Perth House ~67 King Street Branches All States and N.Z.

xwni

Ai)Vf.Rtise]\1Ents

pmffijNAPi STugiT

mm

WIlNfK

and

Spirit

Merchants

The Oldest Established Business In

Sticks

' Jims

a '''lie-'-".

Advhrtisplments

Xxtx

.JlUMtiliJ

ADVERISEMENTg

ininy 9llac/iiner]/ of J{ind6.

Australian Metal Co.

Office & Store: 68 BOULDER ROAD. Telephone 167

- Kalgoorlie. -

Sole Agents in Australasia for

Holman Rock Drills, Patent Stretcher Bar Hoists,

And

All Classes of General Mining Machinery.

Air Compressors, Winding & Pumping Engines, etc.

Manufactured by

Messrs. HOLMAN BROTHERS,

Camborne, England.

Baby Hoist.

Our BABY HOISTS are now being extensively used. Their first cost is saved in one month. No foundation or excavation required.

Sole Agents For

ALL KINDS OF MACHINERY, BOILERS, Etc., by Leading English, European and American Manufacturers : Cyanide of Potassium and Sodium : Steel Rails ; Trucks ; Locomotives, etc. ; Electric Power and Lighting Installations.

MURPHY POPPER DRILLS. Only one moving part. Indisputably the best on the market.

STOCKS KEPT AT FREMANTLE, KALGOORLIE, NORSEMAN, ADELAIDE, BROKEN HILL, MELBOURNE, BENDIGO, SYDNEY and CHARTERS TOWERS.

Our ROCK DRILLS hold the record against every competitor for low cost of upkeep and speed of drilling. Used by nearly every big Mine in the Commonwealth, Can be had on trial before purchase.

Buyers Of All Kinds Of Ores And Metals,

Including

AUSTRALIAN METAL Co.. Ltd., ns william st., Melbourne.

COPPER, LEAD, TIN, ZINC, WOLFRAM, SHEELITE, Etc., Etc. Full particulars on application to Melbourne or Kalgoorlie Offices. Mine in the Commonwealth.

HEAD office:

Rock Drill.

ADVERTISEfENTS

r

George Wills & Co.,

PERTH and FREMANTLE.

And at LONDON, ADELAIDE, PORT ADELAIDE, PORT PIRIE, WALLAROO and BRISBANE.

Merchants, Shipping Agents, Shipping Brokers, Insurance, Customs

Clearing And Forwarding Agents.

V,

Mining Goods On Hand And To Arrive :

COKE (ENGLISH) CANDLES FILTER CLOTH FIREBRICKS and CLAY ORE BAGS PIG IRON

Steel Balls Tram Rails Acetate Of Lead Litharge Bicarb. Soda

BORAX CLASS (20 Mule Team)

CAUSTIC SODA CYANIDE SODIUM CYANIDE POTASSIUM CRUCIBLES CEMENT CASTOR OIL

Galvanized Iron

Paints

Wire

Quicksilver Zinc Shavings Carbide

Agents For

Gas Light & Coke Co. ; Cyanide, Sodium and Potassium ; Sir W. G. Armstrong Whitworth & Co. ; High-speed Tool Steel, Mining Steel, Rock Drills; High-speed Twist Drills and Machine Tools, etc.; Brilliantshine, Metal Polish,; Mineral Wax Candles; Cookson & Co. Ltd.; White Lead.

Contracts Made For Six Or Twelve Months

Kalgoorlie Representative: W. R. BURTON.

s

The Machinery People

A

If you are in want of any Machinery send us particulars, and we will gladly give you complete specifications and estimates.

Xj

Cheap Power

More "CRCSSLEY" Gas Engines and Producer Plants sold in W A than all other makes combined.

1 The best and most reliable in the world.

nr

CAMMELL LAIRD & CO.'S Mining and Tool Steel of all kirids QTFri and sizes. SHOES and DIES. Ball Mill Spares and Battery Parts. Q QtL "Kromella" Brand will last longest.

D

E

R

DAPILIP KARMAL " Packing has been proved to be absolutely the

1 rtU l\l 1 U best for all purposes. Give it a Trial.

REDDAWAY'S Camel Brand Belting will last longer than Q I" I T|UO any other make, and is least affected by weather changes. Ij Q 1 I 1 N M Conveyor and Elevator Belts for all purposes.

Poarn’s Power Pumps. Centrifugal Pumps. Crossley Oil and Benzine Engines.

Steam Boilers and Engines. Steam Pumps. Portable Steam Engines.

Tubes and Fittings for Gas Water and Steam. Ventilating Fans, etc., etc.

Wood and Iron Working Machinery of all kinds.

S

Melbourne Road, Mines Chambers,

. . . Perth. Kalgoorlie.

s

T

Xj

TN Gleland, E Davenport

428 West Australian mining

A8C55 practice

Mining

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