| 摘要 |
2116557 9401364 PCTABS00030 This invention is a process for hydrofluoric acid digestion (20A, 20B, 20C) of an inorganic silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride. A matrix material is reacted with hydrofluoric acid to form silicon tetrafluoride gas and a slurry containing aluminum fluoride, undigested oxides, and both soluble/unsoluble fluoride materials. The silicon tetrafluoride gas is purified by condensing out impurities in cold traps (25) and reacted with aqueous sodium fluoride (30) to form a fluorosilicate salt slurry, which is delivered to a filter press (46) to obtain a powder. The sodium fluorosilicate powder is dried and delivered to a kiln to form silicon fluoride gas and sodium fluoride powder. The aluminum fluoride, undigested oxides, and soluble/unsoluble fluoride materials are recovered by washing, separating using a filter press, and drying in an evaporator while condensing water and excess hydrofluoric acid vapors in a condenser. The aluminum fluorides or metal fluorides are recovered from the dried solution and hydrofluoric acid is collected from the liquid condensate by fractional distillation.
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