METHOD OF PROCESSING HEXAFLUOROSILICIC ACID TO OBTAIN HYDROGEN FLUORIDE Russian patent published in 2019 - IPC C01B7/19 

FIELD: chemistry.

SUBSTANCE: invention relates to processing aqueous solutions of hexafluorosilicic acid, which are formed, in particular, in the process of producing orthophosphoric acid. Method of processing hexafluorosilicic acid to obtain hydrogen fluoride involves alkaline neutralization carried out in two steps. At the first step, the aqueous solution of hexafluorosilicic acid is neutralized with an alkaline agent in ratio of 1.8–2 mol NaOH, KOH, NH₄OH, NH₃ per 1 mol of hexafluorosilicic acid, or 0.9–1 mol of Na₂CO₃, K₂CO₃, CaO, Ca(OH)₂ per 1 mol of hexafluorosilicic acid to obtain suspension of corresponding hexafluorosilicate in water, after which water is removed from the suspension by filtration or centrifugation. At the second neutralization step, the solid hexafluorosilicate is treated with ammonium or an aqueous solution thereof to obtain an aqueous solution of ammonium fluoride. Solid products are filtered, then water solution of ammonium fluoride is preliminarily subjected to evaporation to produce ammonium bifluoride. Obtained ammonium bifluoride is fed for combustion in an oxygen-containing oxidant, hydrogen fluoride and water are condensed from the combustion products, from which hydrogen fluoride is extracted.

EFFECT: disclosed is a method of processing hexafluorosilicic acid to obtain hydrogen fluoride.

1 cl, 1 dwg