Process for producing sodium fluoride from sodium silicofluoride
AssigneeCentral Glass Company, Limited
InventorsTetsuhiro Ono, Minoru Aramaki, Tamotsu Mizuno, Masao Fujinaga
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Abstract
A process for producing sodium fluoride from sodium silicofluoride in which sodium silicofluoride is added to an ammonium fluoride solution for double decomposition reaction to obtain a slurry containing sodium fluoride as crystals and ammonium silicofluoride in dissolved form, and the solution from which the sodium fluoride crystals have been removed is added with ammonia to decompose the ammonium silicofluoride into silica and ammonium fluoride. The ammonium fluoride obtained by the decomposition is recycled to the double decomposition step. Alternatively, the ammonium fluoride is reacted with a sodium salt for recovery as sodium fluoride.
Claims8
A process for producing sodium fluoride from sodium silicofluoride comprising the steps of adding sodium silicofluoride to an ammonium fluoride solution in an Na.sub.2 SiF.sub.6 /NH.sub.4 F ratio by gram equivalent of 0.01 to 0.4:1 for double decomposition reaction at a temperature ranging from room temperature to 100.degree. C to give a slurry containing sodium fluoride as crystals and ammonium silicofluoride in a dissolved form, separating the sodium fluoride crystals from said slurry, adding ammonia to the separated solution to decompose said ammonium silicofluoride into silica and ammonium fluoride, and recovering said ammonium fluoride in a dissolved form and said silica in the form of crystals.
Dependencies are inferred from the claim text.