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Show 103 The U. S. is a net importer of sodium sulphate and there are no government incentives or procurement programs. Uses are varied and a long- term growth rate of three percent per annum has been forecast. Potassium Sulphate ( Potash) Large amounts of schoenite or leonite may be precipitated from the Lake by solar evaporation. Schoehite contains both potassium sulphate and magnesium sulphate. Because magnesium sulphate is more soluble than potassium sulphate, the magnesium sulphate can be leached from schoenite with fresh water, leaving part of the potassium sulphate as a solid. This solid sodium sulphate can then be filtered or centrifuged, washed, dried, and screened. These last processing steps are similar to those for sodium sulphate produced by leaching astrakanite. The percentage potassium is the chief criterion of the suitability of brine for producing potassium salts. Pre- causeway brines had about 0.20 to 0.45 percent potassium. Post- fill South Arm shallow brines have potassium percentages ranging from about 0.30 to 0.55; South Arm deep brines from about 0.45 to 0.60; and North Arm brines from about 0.60 to 0.80. Great Salt Lake Minerals and Chemicals Corporation, the only producer of potassium salts from the Lake, utilizes North Arm brines. Their plant, located west of Ogden, will produce about 240,000 tons of potassium sulfate and 150,000 tons of sodium sulfate. They will have a capability of producing 500,000 tons of magnesium chloride and 4 to 5 million tons of salt annually. The process uses a preconcentration pond, chiefly for holding; salt ponds in which sodium chloride begins to crystallize; and |