METHOD OF PRODUCING SODIUM SILICOFLUORIDE Russian patent published in 2013 - IPC C01B33/10 

FIELD: chemistry.

SUBSTANCE: invention relates to production of fluorine compounds and can be used in production of sodium silicofluoride. Sodium silicofluoride is obtained by neutralising hydrofluorosilicic acid with soda in the presence of a sodium salt at pH 0.2-3 for 0.25-1 h, settling the obtained crystals, separation thereof and drying, wherein the sodium salt used is a sodium fluoride precipitate separated from the reaction mixture, which is obtained by decomposing a calculated amount of hydrofluorosilicic acid with sodium hydroxide solution at pH 11.5-12.5 and temperature 85-95°C, and a calculated amount of hydrofluorosilicic acid fed for decomposition to obtain a sodium fluoride precipitate is determined based on concentration of acid C_H2SiF6 and content of silicon dioxide C_siO2 in the initial hydrofluorosilicic acid using the formula: N=C_siO2×M_H2SiF6/C_H2SiF6×M_siO2=2.4×C_SiO2/C_H2SiF6, where M_M2SiF6 is the molecular weight of hydrofluorosilicic acid, which is equal to 144.09 g/mol, M_SiO2 is the molecular weight of silicon dioxide, which is equal to 60.085 g/mol.

EFFECT: invention enables to obtain an easily filtered end product - sodium silicofluoride with high content of the basic substance.

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