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Show 11.0 man- hours per ton, associated employment could reach 242 in 1975, 606 in 1980, and 1,350 in 1990. L i th ium As solar evaporation progresses and the brines become more and more concentrated, the rate of evaporation becomes lower. Brines which are concentrated to the point that solar evaporation no longer takes place are called bitterns. Evaporating 90 percent of the water by solar evaporation would raise the concentration of lithium in the bitterns from 50 parts per million to several hundred parts per million which is comparable to that of lithium ores. Lithium, which is an alkali metal, makes up 0.015 weight percent of dissolved solids in Great Salt Lake, which is 30 times greater than the weight percent of lithium in dissolved solids of the oceans. Because Great Salt Lake brines are more concentrated than oceanic brines, the absolute enrichment is 150 to 300 times that of the oceans ( Whelan, 1973). Lithium is found in the magnesium bitterns after solar evaporation. Therefore, producers of magnesium metal or magensium chloride, N. L. Industries and Great Salt Lake Minerals and Chemicals Corporation, have the potential to produce lithium chloride and to process this chloride into lithium carbonate or metal. At present, Foote Mineral Company is producing lithium at Silver Park, Nevada, by solar evaporation of subsurface brines containing about 0.4 weight percent lithium. Great Salt Lake brines contain only 0.006 percent. Thus, the concentration of lithium from the Lake brines for commercial purposes depends upon a successful magnesium or potassium |