United States Patent Office Patented Sept
3,000,702 United States Patent Office Patented Sept. 19, 196 2 since potassium fluoride is very soluble. In this case, a 3,000,702 MANUEFACTURE OF SODIUM FLUOR DE double or complex salt is formed in the melt between George L. Cunningham, Burtonsville, Md., assignor to potassium fluoride and the calcium salt and that is slowly W. R. Grace & Co., New York, N.Y., a corporation extracted with water in spite of the great solubility of of Connecticut potassium fluoride in water. The corrosion of the molten No Drawing. Filed May 23, 1958, Ser. No. 737,196 melt is also a considerable problem although suitable 4. Claims. (CI. 23-88) ceramic materials have been discovered for constructing the fusion vessel. This invention relates to a process for the manufac Processes have been devised for the production of so ture of sodium fluoride relatively low in silica content. 10 dium fluoride based on the thermal decomposition of More particularly, this invention relates to a cyclic proc sodium silicofluoride to sodium fluoride and silicon tetra ess whereby sodium fluoride, relatively low in silica con fluoride (U.S. 1,896,697, U.S. 2,588,786, 1,730,915, tent and ammonium chloride, may be manufactured from 2,602,726, and U.S. 1,664,348). These processes are cheap and readily available raw materials. faulty in that relatively high temperatures are required to As manufactured at the present time, technical sodium 15 decompose the sodium silicofluoride and thus it is very fluoride contains 94% to 97% NaF and 1.5% to 5.0% difficult to carry the reaction to completion.
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