524 



UNITED STATES MINERAL RESOURCES 



and yttrium) form a solid solution in the structure 

 of apatite and make up from 0.01 to 0.1 percent by 

 weight of marine apatite. Vanadium probably is 

 concentrated in the organic material associated with 

 phosphorites; the average vanadium content of 

 phosphate rock in the Phosphoria Formation is 

 about 0.03 percent and in Florida phosphate is 0.01 

 percent or less. 



All these minor elements, except scandium, have 

 been or are being recovered from phosphoric acid 

 made by the wet process, and vanadium is now re- 

 covered in the course of thermal processing. Because 

 only about one-fourth of the phosphate rock mined 

 is made into phosphoric acid, the maximum recovery 

 of the minor elements can only be about 25 percent. 

 The probability of the recovery of scandium from 

 this source seems remote. Research is needed to de- 

 velop better methods of recovery of all these ele- 

 ments. 



Recovery of some of the elements is related to 

 reduction in air and water pollution. Fluorine, re- 

 leased in part as a gas in the chemical processing, 

 cannot be allowed to escape in the effluent. Fluorine 

 in the gas effluents is being controlled, but not all is 

 being recovered. Research on methods of recovery 

 of byproducts may lead to cleaner air and water 

 effluents. 



Solid wastes formed in processing, particularly 

 the slime ( — 200 mesh) fraction from the deposits 

 on the Atlantic Coastal Plain, cannot be dumped 

 into streams and are currently impounded in dams. 

 Breaks do occur, causing water pollution. The slime 

 fraction is a potentially valuable fertilizer, and re- 

 search on control, disposal, and possible utilization 

 of the slime fraction is of utmost importance. 



All open-pit mining, chemical processing, and dis- 

 posal of mining and chemical wastes are now and 

 will be increasingly regulated by clean air and water 

 laws and by land reclamation laws. The phosphate 

 mining and processing companies are reclaiming 

 land in Florida and Tennessee and are working to 

 solve problems of air and water pollution, but addi- 

 tional research is certainly needed. If there is any 

 significant air or water pollution or ruining of land 

 by mining in the future, legislation could force phos- 

 phate mining companies out of business and dras- 

 tically change the export-import balance of phos- 

 phate trade. 



Mining of phosphate rock is geared to shallow 

 open pits and to underground mining above entry 

 level. To utilize much of the hypothetical resources 

 in the United States, new or different mining meth- 

 ods will have to be devised, and processing methods 

 to recover the phosphate particles will also have to 



be changed. Much of the hypothetical resource is 

 carbonate rock containing phosphate pellets, and the 

 recovery methods currently used are not effective. 

 Although minable reserves are sufficient for many 

 years, the beginning of research on mining and 

 processing problems should not wait until these re- 

 serves are nearly exhausted, but should be started 

 promptly. 



An additional set of chemical problems has to do 

 with the amount and kind of trace metals present 

 in phosphate rock. Certain minor elements are neces- 

 sary for plant growth ; among these are boron, 

 copper, manganese, molybdenum, and zinc. These 

 elements are all present in marine phosphorites, but 

 are removed during chemical processing, only to be 

 readded to the chemical fertilizer in about the same 

 amount that was removed. Research is needed on 

 methods of retaining these minor elements in 

 chemical processing of phosphate rock. 



Geologic problems are related particularly to the 

 discovery of new ore deposits of high grade. The 

 hypothesis that marine phosphorites were deposited 

 in miogeosynclines at some distance from the 

 source of clastic sediment and only at low latitudes 

 has proved workable. Each miogeosynclinal basin 

 should be investigated particularly with respect to 

 plate tectonics and the paleolatitude of the basin at 

 the time of phosphate deposition. Thus, a knowledge 

 of paleogeography, paleolatitude, paleocurrents and 

 wind directions, and structure within the basin at 

 the time of deposition is all important in determin- 

 ing the locus of possible phosphorite deposition. 



For deposits on the east coasts of continents — 

 the Florida-type deposits — again a knowledge of 

 structure, geography, and current and wind direc- 

 tions is important. These deposits are likely to be 

 buried, and any geologic parameters that might be 

 used to reduce the size of the target area to be 

 drilled are of great importance. 



Much remains to be learned about the chemistry 

 of deposition of marine phosphorites. Phosphate 

 may be precipitated chemically and biologically. The 

 source of the phosphate might be ocean water itself, 

 rivers entering the ocean, estuaries, the phosphatic 

 bodies of fish and animals, or volcanic emanations 

 onto the ocean floor, or some combination of all of 

 these. The marine phosphorites are large ; they con- 

 tain billions of tons of phosphorus, and whatever 

 the source, the phosphorus has to be available over 

 long periods of time. 



Problems of reserves would not appear to be im- 

 portant, in view of the extremely large identified 

 tonnages, but phosphate is a low-unit-value com- 

 modity and shipping costs can put the material out 



