Uranium in phosphate rock
<p>Uranium is a trace constituent of all apatites in amounts that typically range from <0.001 to 0.003 percent for guano and guano-derived deposits; from…
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11,11111!!!!!!!!!!!111 UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY, URANIUM IN PHOSPHATE ROCK By James B. Cathcart Open-file report 75-321 This report is preliminary and has not been edited or reviewed for conformity with U.S. Geological Survey standards and nomenclature. ( 200) R290 no.75-321
Contents Page Abstract Introduction2 Guano and guano-derived deposits Igneous apatite deposits Marine phosphorite Secondary deposits Other deposits Lake beds Offshore deposits Phosphate and uranium resources References
Tables Page Table 1. Guano and guano-derived phosphate: reserves, production, and uranium content 2. Igneous apatite: reserves, production and uranium content 3. Marine phosphorite: reserves, production, and uranium content 4. Secondary phosphate deposits: reserves, production, uranium content 5. Other phosphate deposits: reserves, production, uranium content 6. Resources of uranium in sedimentary phosphorites16
URANIUM IN PHOSPHATE ROCK By James B. Cathcart Abstract Uranium is a trace constituent of all apatites in amounts that typically range from <0.001 to 0.003 percent for guano and guano-derived deposits; from 0.001 to 0.010 percent for igneous apatites; from 0.005 to 0.030 percent for marine phosphorites. Uranium may be enriched to as much as 0.05 percent in phosphorites reworked in a marine environment, and isolated bones and concretions may contain as much as 0.8 percent uranium as a result of enrichment by ground water. Uranium as replaces calcium in the apatite structure. Possibly some occurs as U04-2 groups. Uranium is readily removed from apatite by weathering, and enrichment of phosphate after deposition may be entirely residual, as in the case of the brown rock deposits of Tennessee, or uranium may be added as in the case of the lateritic weathering of the deposits in Florida. Uranium has been recovered as a byproduct of the manufacture of phosphoric acid by the wet process. In 1972, about 15 million tons of phosphate rock was used to make phosphoric acid in the United States. This phosphoric acid probably contained about 1500 tons of uranium. An additional 10 million tons, worldwide, was made into phosphoric acid, and thus, 1000 tons of uranium was in solution. Increased demand for phosphatic fertilizers and increases in the amount of phosphate rock used to make phosphoric acid makes it likely that tonnages of uranium in phosphoric acid will reach 5000 tons per year within the next 25 years. Thus, marine phosphorites are a significant source of uranium for the future.
Introduction Uranium is present as a trace constituent in all apatites, in amounts that typically range from 0.003 to 0.030 percent. Strutt (1908) first discovered that phosphatic rocks and fossil bones are appreciably more radioactive than the average rocks of the crust and his data that showed that certain British phosphorites and fossil bones contained from 0.005 to 0.015 percent U308 were remarkably accurate. Wells (1929) pointed out that a shark's tooth from the Pliocene of Florida contained 0.021 percent U--the first published record of the uranium in the phosphate deposits of Florida, and Hebert (1947) stated that as early as 1924 it was known that the Cretaceous and Eocene phosphorites of Algeria contained uranium. The first mention of uranium in the Cretaceous and Tertiary phosphate deposits of the USSR was published by Rusakov (1933). The developments of uses of uranium as an energy source provided the impetus for research into all potential sources, and apatites from all parts of the world were tested for uranium. Detailed studies of uranium in phosphate have been made by Altschuler (1973), Altschuler, Clarke, and Young (1958), Altschuler, Jaffe, and Cuttitta (1956), Cathcart (1956), Davidson and Atkin (1953), McKelvey (1956), McKelvey and Carswell (1956), McKelvey, Everhart, and Garrels (1955), and Sheldon (1959). Much of the data presented in this paper is derived from these works, and each of them contains an extensive bibliography. Phosphorus is found in minable concentrations in three environments- as guano or in deposits derived from guano, as igneous apatite, and as marine phosphate deposits; and in secondary deposits formed from each of these by weathering. Guano and guano-derived deposits Guano deposits are formed from the excreta of sea birds and from the excreta of bats in caves. Guano derived deposits are formed when the soluble phosphate in guano is dissolved by ground water and reacts with the underlying rocks to form apatite when the rock is limestone or to form iron and aluminum phosphates when igneous rocks underlie the guano.
About 5 percent of the world's production of phosphate is from guanoderived deposits, and a very small amount is from deposits of guano (table 1). Guano contains from less than 0.001 to about 0.003 percent U (Altschuler, and others, 1958), but guano-derived deposits contain as much as 0.008 percent (Davidson and Atkin, 1953). Recent analytical data (U.S. Geological Survey Denver Laboratory: E. J. Fennelly and Johnnie Gardner, analysts) show that guano-derived phosphate from Curacao contains 0.002 percent U, and that from Nauru contains 0.005 percent. The higher uranium contents (0.005-0.008 percent) are from those samples that are also high in fluorine, that is, in which the phosphate mineral is a carbonate fluorapatite, rather than a hydroxyapatite. The samples are from tidal zones where fluorine and uranium were added from sea water. Igneous apatite deposits Apatite deposits of igneous origin occur as intrusive masses, as veins, as marginal differentiates, or as pegmatites. The largest deposits are intrusive masses associated with alkalic rocks, such as carbonatite, nepheline syenite, pyroxenite, and ijolite. The apatite mineral is a fluorapatite, and ranges in amount from a few percent as an accessory mineral to as much as 80 percent in some pipes and sheets. The apatitic masses range in size from a few square metres to tens of square kilometres and the amounts of apatite present range from a few tons to hundreds of millions of tons. The largest deposits include those from the Kola Peninsula (USSR), Palabora and eastern Uganda (Africa) and Araxa (Brazil). In 1970, about 17 percent of the world's production of phosphate came from igneous apatite deposits, and about 80 percent of this production was from the deposits of the Kola Peninsula. The uranium content of primary fluorapatite of igneous rocks typically ranges from 0.001 to 0.010 percent (Altschuler, and others, 1958; Davidson and Atkin, 1953), although individual samples may contain as much as 0.079 percent U (table 2). Thorium is not usually present, except in very minute amounts, but an apatite sample from a pegmatite from Bahia, Brazil contained 0.005 percent U and 1500 ppm Th (thorium analysis by Nancy Conklin, and uranium analysis by E. J. Fennelly, U.S. Geol. Survey).
Table 1.--Guano and guano-derived phosphate: reserves, production and uranium content. Reserves Production Uranium Location (metric tons) (metric tons per yr) content (percent) Bird guano Peru--Pacific Coast Limited, 0.1 x 106 renewable Chile-Pacific small Coast 0.01x 106 Cave (bat guano) <0.001-0.003 Mexico Very small, total Philippines is about 0.02-0.04 x 106 Africa Guano-derived (calcium phosphate minerals) Nauru Island 100 x 106 1.8 x 106 0.005-0.007 Christmas Island 0.7 x 106 Makatea Island Ocean Island 0.001-0.002 Curacao Anguar Guano-derived (iron and aluminum phosphate Malpelo Island, Colombia 0.4 x 106 None No data Trauira Island, Brazil None No data Saldanha Bay, South Africa 0.3 x 106 None No data Kito-Daito-Jima Ryukyu Islands None No data, ' Only the largest of the aluminum and iron phosphate deposits are listed. Others are known, but reserves are limited and none are being mined today. The deposits of Kito-Daito-Jima have been mined. Uranium contents of these deposits are not known, but are thought to be small, of the order of magnitude of 0.001 percent.
Table 2.--Igneous apatite: reserves, production and uranium content. Production2 Uranium Location Reservesl (metric tons content3 (metric tons) per year) (in percent) Kola Peninsula--USSR 0.001-0.003 Palabora-South Africa 0.4 x 109 0.6 x 106 0.003-0.004 North Korea 0.1 x 109 0.2 x 106 No data. Brazil 0.15 x 109 0.2 x 106 (carbonatites) Dorowa-Southern 0.1 x 109 0.1 x 106 No data. Rhodesia Uganda 0.2 x 109 0.01 x 106 50.013-0.030 Antofagasta-Chile 0.02 x 109 0.01 x 106 No data. Mineville district Very small None New York, USA 1 1n metric tons of total rock containing more than 10 percent P205. 2In metric tons of apatite concentrate containing at least 25 percent P205. 3In percent, of the apatite concentrate. 40ne sample, from Araxa. A sample of apatite from a pegmatite in Bahia, ,Brazil, contained 0.010 percent eU, 0.005 percent U, and 1500 ppm Th. 5Percent U308, from Davidson and Atkin, 1953.
Marine phosphorite Marine phosphorite deposits are known throughout the world and in all geologic ages from Precambrian to Holocene. The richest of these deposits form in basins away from abundant sources of clastic material in warm latitudes in areas of upwelling water. The deposits may be very large--reserves in individual deposits are billions of tons; total reserves aggregate scores of billions of tons, and resources are proportionately larger (Cathcart and Gulbrandsen, 1973). About 84 percent of the world production of phosphate comes from marine phosphorites; from 1970 through 1972 production in the United States has been about 40 million tons per year; 83 percent from Miocene and Pliocene deposits in Florida and North Carolina, 11 percent from the Permian deposits of the western states, and 6 percent from Ordovician deposits in Tennessee and Alabama. Some production from the Miocene of California is included in the total for the western states. Every deposit that has been analyzed contains uranium, in amounts that typically range from 0.005 to 0.030 percent, while the average uranium content for most deposits is in the range from 0.005 to 0.010 percent (table 3). The relative uniformity of the analytical data indicate strongly that deposits for which data are not available almost certainly contain similar amounts of uranium--that is, ranging from about 0.005 to 0.020 percent and averaging about 0.006-0.008 percent uranium. Uranium is associated with the apatite mineral (carbonate fluor apatite), and most workers agree that uranium as replaces calcium in the apatite structure (Altschuler and others, 1958). The uranium-apatite association is clearly demonstrated by several lines of evidence, for example, chemical analyses of the minerals associated with apatite in the Florida deposits show that they contain virtually no uranium; in a general way, uranium varies directly with P205 content (Cathcart, 1956, Thompson, 1953 and 1954); and the amount of uranium dissolved on acidulation of phosphate rock varies directly with the amount of phosphate dissolved (Igelsrud and others, 1948).
Table 3.--Marine phosphorite: reserves, production, and uranium content. Location Reserves' Production' Uranium content2 United States Central Florida 2.1 x 109 0.003-0.030, average concentrate 0.011, average pebble 0.015. North Florida 0.3 x 109 0.004-0.011, average South Georgia 0.006. North Carolina 0.004-0.011, average 0.006. North Georgia (Savannah River) South Carolina (Beaufort County) (Charleston area) Reserves not measured; resources are billions of production 0.005-0.037 Florida-Georgia tons 0.003-0.008, average (Hawthorn Formation) 0.005. Idaho, Montana, Utah, 0.002-0.021, average Wyoming (Phosphoria) 0.009 Utah (Brazer 1st) Measured re 0.001-0.006 Alaska (Permian) Others (Ala. Ark., Ky., Iowa, Kans., Okla., Calif., Nevada) serves are small; re sources, particularly in Alaska are billions of production 0.001-0.024, average 0.008. Rock: 0.001-0.014; nodules: 0.0090.030 in black shale and limestone. tons Africa Algeria 0.1 x 106 0.011-0.014 Angola No data. Morocco 0.007-0.023 Senegal /20 x 109 0.7 x 106 0.012-0.018 Togo No data. Tunisia 0.004-0.009 U.A.R. (Egypt) 0.6 x 106 0.007-0.012 Spanish Sahara 0.005-0.011
Table 3.--Marine phosphorite--Continued: Location Reserves) Production) Uranium content2 Asia China No data. Laokay-North Vietnam 0.1 x 109 No data. India 0.1 x 109 0.1 x 106 0.003-0.100 Iran 0.05 x 109 No data. Iraq 0.1 x 109 No data. Israel 0.1 x 109 0.002-0.020 Jordan 0.1 x 109 0.5 x 106 No data. Mongolia No data. No data. Saudi Arabia 0.2 x 109 None 0.002-0.011 average =0.006. Turkey 0.2 x 109 None Australia None 0.001-0.013 average =0.009 Europe USSR O. 05-0.010 Others (Belgium, Small 0.1 x 106 0.001-0.021 average Germany, France =0.006 England, Spain) Latin America Mexico 0.15 x 109 No data. Colombia 0.2 x 109 Production is a few tens of 0.004-0.012 average =0.008. Venezuela 0.1 x 109 thousands 0.005 Peru (Sechura) 1+ x 109 of tons per yr. Brazil (Bambui) Small 0.001-0.005 average =0.002 lin metric tons of recoverable phosphate product containing at least 24 per cent P205. 2Uranium in percent, of the phosphate product, except as noted.
The syngenetic character of uranium in marine phosphate is well demonstrated in the distribution in the Florida phosphate deposits. Primary phosphate pellets in the Hawthorn Formation are low in uranium content--average about 0.005 percent. The phosphate pellets in the overlying Bone Valley Formation were reworked from the Hawthorn Formation in a marine environment, and the concentrate size particles (the pellets) contain an average of 0.011 percent U (table 3). The pebble fraction (+1 mm) contains an average of 0.015 percent U, and the coarse pebbles that show evidence of several cycles of reworking in the marine environment contain as much as 0.05 percent U (Cathcart, 1956, Altschuler and others, 1958). Thus, primary pellets contain the least amount of uranium, pellets reworked once in a marine environment contain much more uranium, and pebbles reworked several times contain the most uranium. That uranium was not emplaced by ground waters percolating through the deposits is indicated by the fact that the fine-grained pellets, highest in P205 content, always contain less uranium than the lower-P205-content pebble fraction even in deposits that contain 90 percent fine phosphate pellets and only 10 percent pebble size. Uranium in solution in ground water is taken up by apatite, and phosphatic bones, concretions, pellets and pebbles may be strongly enriched in uranium. Thus, isolated bones may contain up to 0.83 percent uranium (Altschuler and others, 1958), individual concretions and nodules as much as 0.1 percent (Davidson and Atkin, 1953), and individual samples of pellets from Florida as much as 0.5 percent. These abnormally high contents of uranium are cited to indicate the amount of enrichment that can be accomplished under special conditions. Under normal marine conditions, the extremely small amount of uranium in sea water probably accounts for the low, rather uniform content of uranium in these apatites.
Secondary deposits Uranium is readily leached from apatite during weathering and under acid ground water conditions both apatite and uranium are dissolved. The end products of weathering and the distribution of uranium in the products depend on the type of source rock and the length and severity of the weathering. When the original rock is a phosphatic limestone, weathering removes calcite, leaving a residually enriched phosphorite. In the case of the residual "brown rock" deposits of Tennessee, both the uranium and the P205 contents are increased in the residual material by the same factor--there is no preferential enrichment of uranium. When calcite is gone, the apatite goes into solution and moves downward where it replaces the under lying limestone. In replacement deposits there tends to be a preferential enrichment in uranium, and uranium contents of as much as 0.1 percent have been noted in the secondary apatite hardpan on the Cooper Marl of South Carolina (Altschuler and others, 1958). Replacement type deposits are known in many parts of the world. Individual deposits tend to be small, irregular in shape, and high in P205 content. Uranium contents typically range from 0.001 to 0.017 percent (table 4), although much higher contents are known. Measured reserves are small, but total resources may be fairly large. Intensive weathering by acid ground water of sandy phosphorites produces irregular zones of porous, vesicular, light-colored, and light weight rocks characterized by aluminum phosphate minerals. These zones have been described from Florida, Nigeria, Senegal, and Siberia (Altschuler, 1973). All of the deposits are similar and are characterized by the change of apatite to crandallite or millisite and to wavellite as an end product. These changes are accompanied by the change of the original clay minerals (montmorillonite or illite) to kaolinite. Uranium is enriched in these deposits, and it is associated almost entirely with the phosphate minerals, and preferentially with the calcium aluminum phosphate minerals--crandallite and millisite, or with the calcium phosphate mineral apatite. The uranium minerals autunite (from
Table 4. Secondary phosphate deposits; reserves, production, uranium content Location Reserves Production Uranium content Replacement deposits--calcium phosphate Florida-hardrock 0.05 x 10 none 0.001-0.017; -200 mesh from 0.001-0.023. Tennessee "whiterock" small none South Carolina "phosphatic v. small none 0.035-0.12 hardpan" Venezuela Riecito area 0.01 x 10 "few thousand tons per year' no data Russia no data no data 0.001-0.01011 Residual deposits--calcium phosphate Tennessee "brown rock" 0.08 x 10 0.001-0.003Aluminum phosphate deposits Florida landpebble district 0.05 x 10 none 0.004-0.0401 Senegal 0.05 x 10 no data Nigeria v. small none 0.004-0.011 Siberia-USSR no data, small(?) none no data lfUranium analyses by E. J. Fennelly and Johnnie Gardner, U.S. Geol. Survey, Denver 3/Unaltered limestone from which the residual deposits formed contains 0.0004 percent U. --/Typical range in uranium contents. Individual samples may contain as much as 0.3 percent U.
Florida) and torbernite (from Morocco) have been reported from the aluminum phosphate zones, but only in trace amounts and only in limited areas within the deposits. Uranium is highest and most enriched in the porous, partly leached apatite pebbles at the base of the zone of leaching, and amounts of uranium are as high as 0.3 percent in these pebbles. Concentrates of the calcium aluminum phosphate minerals crandallite and millisite contain as much as 0.05 percent uranium (Altschuler, 1973), but concentrates of the aluminum phosphate mineral wavellite contain almost no uranium, probably averaging only about 0.003 percent. In Florida, the total zone of aluminum phosphate alteration may be enriched in uranium, as much as 2 to 4 times over the original, unaltered calcium phosphate zone from which it was derived. Uranium is liberated during the solution of the apatite, remains soluble in the descending acid solutions and enriches the crandallite and the partly leached apatite pebbles at the base of the section. Because wavellite is continuously formed from crandallite in the middle parts of the zone, the uranium in the crandallite goes into solution and moves downward to further enrich the underlying apatite, accounting for the abnormally high uranium contents in some of this apatite. Other deposits Lake beds Tertiary lake beds in Wyoming and Nevada contain some beds of uraniferous phosphate. Lake beds near Tonopah, Nevada, contain 6.7 and 11.0 percent P205 and 0.10 and 0.12 percent eU (unpublished analyses, U.S. Geological Survey, by Carmen Johnson and Maryse Delevaux). Lake beds of Eocene age in Wyoming and Utah contain as much as 0.27 percent U and 19 percent P205, although average contents of both are much less (Love, 1964). Many very thin beds containing the phosphate and uranium are present; the beds average less than a foot in thickness. The uraniferous phosphate beds are thought to be syngenetic, and although these occurrences are not economic, they indicate the possiblity that in other, similar lake
basins, economic beds of uraniferous phosphate might be present. Tonnages are not known; they may be large in aggregate because of the extent of the beds, but tons per unit area are probably small. Offshore deposits Phosphate nodules and pellets are present on the floors of the modern oceans and have been investigated on the west coast of North America from Monterey Bay south to Baja, California, on the east coast of the United States from North Carolina to Florida, and along the west coast of Africa. Some of the nodules are thought to be forming in the modern oceans (as those of offshore California); others are thought to be reworked from older phosphatic sediments (those of offshore North Carolina and the west coast of Africa). Amounts of pellets and nodules in the modern sediments range from traces to as much as 60 percent by volume, but probably average between 5 and 10 percent, and resources probably aggregate billions of tons although adequate measurements of reserves have not been published. Uranium contents range from 0.001 to 0.012 percent (Altschuler and others, 1958), and a single sample from offshore California contained 26.4 percent P205 and 0.021 percent U (U.S. Geological Survey analysis by M. Finch, C. Angelo, and P. Schuch). The analytical data are similar to data from older marine phosphorites, and there is no reason to believe that other deposits, not analyzed, will contain very different amounts of either uranium or phosphate.
Phosphate and uranium resources Phosphate reserves, defined as identified mineral deposits whose grade and tonnage are reasonably evaluated and may be economically re coverable under present conditions, along with their uranium contents are given in tables 1 through 5. All reserves are in metric tons of mineral that contains at least 24 percent P205. The uniformity of uranium content of marine phosphorites (0.006-0.010 percent) is striking and indicates that average U content and total resources are probably reason able numbers. Data on phosphate resources of the world are given by Cathcart and Gulbrandsen (1973) and these data are summarized and brought up to date (July 1974) in table 6. Average uranium content and total uranium resources are also indicated in the table. Uranium has been recovered as a byproduct only in the manufacture of phosphoric acid by the wet process. Newspaper articles (early 1974) indicate that plans are being made to again recover uranium from phos phoric acid by the same process, but which has been technically improved. Available data clearly indicate that uranium is recoverable only from phosphoric acid. Thus, of the total amount of uranium present in the phosphate resources (table 6), from one-third to one-half, is potentially recoverable because these fractions are being and will be made into phosphoric acid. The latest available data show that about 15 million tons, about one-third of the total production of phosphate rock in the United States, went into the manufacture of wet process phosphoric acid (Stowasser, 1972). The phosphate rock used in phosphoric acid production probably contained an average of 0.010 percent U, and, therefore, contained 1500 tons of uranium. Projections for the future are speculative, but the needs of an increasing population for fertilizer indicate that the production of phosphate will increase in the future. Latest figures for planned in creases in capacity indicate that by 1980 the United States will have the capacity to produce almost 60 million tons per year of rock phosphate, an increase of about 50 percent from the production of about 40 million tons of rock in 1973. World capacity by 1980 should be 160 million tons
Table 5.--Other phosphate deposits: reserves, production, uranium content. Location Nevada (Tertiary) Wyoming, Utah (Eocene) California (Monterey Bay to Baja, Calif.) Florida, Georgia, South and North Carolina South Africa Capetown Northwest Africa Rabat to Mauritania Reserves Lake beds Probably small Area is large, but beds range from 3" to 6' in thickness Offshore Large Large No data, maximum apatite con tent is 15 percent No data, apatite content 10-60 percent, re worked from older beds Production None None None None None None Uranium content 0.10, 0.12 0.001-0.29 average 0.001-0.021 No data, probably average 0.005. No data. No data, but U con tent should be the same as the deposits of North Africa, from which these deposits probably were derived.
Table 6.--Resources of uranium in sedimentary phosphorites. [Modified from table 106 Cathcart and Gulbrandsen (1973). In metric tons of rock containing 20 percent or more P205.] Identified Hypothetical Percent31 Total tog resources— / resources uranium— uranium i United States 3,150,000 Africa 8,500,000 Near East and Asia 1,600,000 Latin America 800,000 Australia 780,000 Pacific Islands 15,000 1/Identified resources are defined as identified mineral deposits that may or may not be evaluated as to extent and grade, and whose contained minerals may or may not be profitably recovered with existing technology. !Hypothetical resources are defined as undiscovered mineral deposits, whether or recoverable or subeconomic grade, that are geologically predictable as existing in known districts. 3/Percent uranium is a reasonable average taken from tables 1, 2, and 3 in this report. AiTotal tons of uranium is metric tons present in the identified plus hypothetical resources.
as compared with 110 million in 1972. At a production of 60 million tons per year, reserves in Florida and North Carolina will last until about 2000, after which the production rate from this area will decrease, and the slack will have to be taken up by the western deposits. If these numbers are correct, by 1980, the United States will be using 20 million tons of phosphate rock per year for making phosphoric acid. If demand for phosphate rock continues to increase, the United States in the year 2000 will use about 50-60 million tons of phosphate rock per year for making phosphoric acid (F. E. McGinley, USAEC, written commun., 1974). The amount of uranium in phosphoric acid in the United States, then, will increase from 1500 tons per year in 1972 to 2000 tons per year by 1980, and potentially to as much as 6000 tons per year by 2000. If the rate of increase is uniform, by the year 1980 13,400 tons of uranium could be pro duced from phosphoric acid, and by the year 2000, more than 95,000 tons could be produced. These figures assume that production of uranium will be from all of the phosphoric acid made. Certainly, production will not be this high, and McGinley (written commun., 1974) estimated that produc tion recovery from acid would be about 90 percent, and that about 70 per cent, of the total acid produced would be treated in uranium recovery plants by 2000. The totals would then be reduced to about 60,000 tons of uranium that might be recovered in the years 1975-2000. The very large amounts of phosphate projected for use by the year 2000 are in excess of what can be produced in the eastern United States, unless there is added production from the north Florida-south Georgia area, the Savannah River area of north Georgia, the North Carolina field, and possibly the southern extension of the Bone Valley district of central Florida. It seems probable that imports of phosphate rock and production from the western United States will have to increase drastically before the end of this century to take care of potential demands for phosphate rock. A substantial portion of the total production of phosphate rock is exported (about one-third in 1973), but planned increases in capacity throughout the world indicate that our exports will decrease in the future.
The total tonnage of uranium present in the phosphorites of the United States, particularly the large hypothetical resource, might lead to misapprehension as to the total amount of uranium that can be recovered from this source. First, much of the hypothetical resource is probably not minable, for a variety of reasons. Second, uranium can be recovered only from phosphoric acid made by the wet process--i.e., by treating phosphate rock with sulfuric acid. Projections for the near future- capacity increases to 60 million tons of rock that could be mined, and 20 million tons used to make phosphoric acid by 1980, are realistic--they are based largely on announced increases, and there is little chance that these numbers can be substantially increased because, for example, of difficulties in obtaining special steels needed for chemical plants, draglines, and so on. The longer range projections are based on what seem to be realistic guesses on amounts of phosphate rock that will be needed to satisfy the demands for phosphate fertilizer. If all phosphate rock mined were to be converted to phosphoric acid, the total amount of uranium that could be recovered would, of course, be doubled or tripled, but this is not believed possible--first, because of vastly increased amounts of sulfur required, and second, beause it would entail the use of vast amounts of phosphate rock for purposes other than fertilizer, and phosphate as a fertilizer is necessary for food production. It might be argued that the phosphoric acid could be stored until needed as a fertilizer material (a difficult proposition, because of its corrosive nature), but it must be mixed with ground phosphate rock (in about equal amounts) to make one of the most used fertilizers--treble superphosphate, or mixed with aqueous ammonia to make diammonium phosphate. The manufacture of ammonia requires abundant natural gas as a source of hydrogen, and vastly increased amounts of ammonia would be needed if this use is contemplated. Other needs for natural gas, and its overall shortage, would seem to preclude this use for the material. In short, it is most probable that the projected tonnages for re coverable uranium from phosphate rock are about maximum possible, consid ering all factors.
References Altschuler, Z. S., 1973, The weathering of phosphate deposits--geochemical environmental aspects, in Griffith, E. J., Beeton, A., Spencer, J. M., and Mitchell, D. J., eds., Environmental Phosphorus Handbook: John Wiley & Sons, New York, p. 33-96. Altschuler, Z. S., Clarke, R. S., Jr., and Young, E. J., 1958, Geochemistry of uranium in apatite and phosphrite: U.S. Geol. Survey Prof. Paper 314-D, 90 p. Altschuler, Z. S., Jaffe, E. B., and Cuttitta, Frank, 1956, The aluminum phosphate zone of the Bone Valley Formation, Florida, and its uranium deposits: U.S. Geol. Survey Prof. Paper 300, p. 495-504. Bliskovskiy, V. Z., and Smirnov, A. I., 1966, Radioactivity of phosphorites: Geokhimiya no. 6, p. 744-747. Cathcart, J. B., 1956, Distribution and occurrence of uranium in the calcium phosphate zone of the land-pebble district of Florida: U.S. Geol. Survey Prof. Paper 300, p. 489-494. Cathcart, J. B., and Gulbrandsen, R. A., 1973, Phosphate deposits: U.S. Geol. Survey Prof. Paper 820, p. 515-525. Cook, P. J., 1972, Petrology and geochemistry of the phosphate deposits of northwest Queensland, Australia: Econ. Geology, v. 67, p. 1193-1213. Davidson, C. F., and Atkin, D., 1953, On the occurrence of uranium in phosphate rock: Internat. Geol. Cong., 19th, Algiers 1952, Comptes Rendus Sec. 11, pt. 11, p. 13-31. Gulbrandsen, R. A., 1966, Chemical composition of phosphorites of the Phosphoria Formation: Geochim. et Cosmochim. Acta, v. 30, p. 769-778. Hebert, Claude, 1947, Contribution a l'etude dela chimie de phosphates de calcium: Anales des mines, Memoirs, v. 136, no. 4, p. 5-93. Igelsrud, Iver, Stephen, E. F., Chocholak, John, Schwartz, C. M., and Austin, A. E., 1948, Chemical process to recover uranium from phos phate rock: U.S. Atomic Energy Comm., BMI-JDS-126, 29 p. Love, J. D., 1964, Uraniferous phosphatic lake beds of Eocene age in inter mountane basins of Wyoming and Utah: U.S. Geol. Survey Prof. Paper 474-E, 66 p.
McKelvey, V. E., 1956, Uranium in phosphate rock: U.S. Geol. Survey Prof. Paper 300, p. 477-481. 1967, Phosphate deposits: U.S. Geol. Survey Bull. 1252-D, 21 p. McKelvey, V. E., and Carswell, L. D., 1956, Uranium in the Phosphoria Formation: U.S. Geol. Survey Prof. Paper 300, p. 483-488. McKelvey, V. E., Everhart, D. L., and Garrels, R. M., 1955, Origin of uranium deposits: Econ. Geology 50th Ann. Vol., Pt. 1, p. 464-533. Patton, W. W., Jr., and Matzko, J. J., 1959, Phosphate deposits in northern Alaska: U.S. Geol. Survey Prof. Paper 302-A, 17 p. Rasakov, V. P., 1933, 0 soderzhanii radiya i torija v fosforitakh [Radium and thorium contents of phosphorites]: Akad. Nauk SSSR, LeningradMoscow, Doklady, Series A, no. 3, p. 25-33. Saraswat, A. C., Varada Rajo, H. N., Taneja, P. C., Bargaja, V. B., and Sankaran, A. V., 1972, Geochemical data on the uraniferous phos phorites of Musoorie, Dehra Dun district, Uttar Pradesh, India: ECAFE-UNESCO document 13 p. Sheldon, R. P., 1959, Geochemistry of uranium in phosphorites and black shales of the Phosphoria Formation: U.S. Geol. Survey Bull. 1084-D, p. D83-D115. Stowasser, W. F., 1972, Phosphate rock crop year annual: U.S. Bureau of Mines, Mineral Industry Surveys, 6 p. Strutt, R. J., 1908, On the accumulation of helium in geologic time: Royal Soc. London Proc., ser. A, vol. 81, p. 272-277. Thompson, M. E., 1953, Distribution of uranium in rich phosphate beds of the Phosphoria Formation: U.S. Geol. Survey Bull. 988-D, p. D45-D67. 1954, Further studies of the distribution of uranium in rich phosphate beds of the Phosphoria Formation: U.S. Geol. Survey Bull. 1009-D, p. D107-D123. Wells, R. C., 1929, Age of minerals and rocks on the basis of radioactive disintegration: in Tekhnisheskaya Entsiklopediya, Sporavochnik fizicheskikhi khimicheskikha i technologkheskikh velichin, v. 2, p. 60-63. Wurzburger, U. S., 1968, A survey of phosphate deposits in Israel: U.N. Mineral Res. Series no. 32, p. 152-165.
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