METHOD FOR SYNTHESIS OF SODIUM SILICOFLUORIDE Russian patent published in 2011 - IPC C01B33/10 

FIELD: chemistry.

SUBSTANCE: invention can be used in processing fluorine-containing gases from production of wet-process phosphoric acid and fertiliser. Gases are absorbed with water. The obtained hydrofluorosilicic acid is then neutralised with soda at pH 0.2-3 for 0.25-1 hour in the presence of sodium sulphate. Weight ratio of soda to sodium sulphate equals 1 : (0.1-0.4).

EFFECT: invention increases output of sodium silicofluoride to 98,5 wt % and reduces residual content of fluorine in waste water.

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