METHOD OF PRODUCING HYDROGEN FLUORIDE FROM HEXAFLUOROSILICIC ACID Russian patent published in 2019 - IPC C01B7/19 

FIELD: chemistry.

SUBSTANCE: invention relates to processing solutions of hexafluorosilicic acid formed during production of orthophosphoric acid. Method of producing hydrogen fluoride from aqueous solution of hexafluorosilicic acid involves neutralization of a solution of hexafluorosilicic acid with an alkaline agent in ratio 1.8–2 mol of NaOH, KOH, NH₄OH, NH₃ per 1 mol of hexafluorosilicic acid or 0.9–1 mol Na₂CO₃, K₂CO₃, CaO, Ca(OH)₂ per 1 mol of hexafluorosilicic acid. Then, the formed hexafluorosilicates are recovered from the suspension, treated in a flame of hydrogen-containing fuel and an oxygen-containing oxidant, cooling of combustion products, removal of silicon dioxide therefrom and condensation of hydrogen fluoride and water with subsequent extraction of hydrogen fluoride.

EFFECT: extraction of fluorine in the form of hydrogen fluoride from water solution of hexafluorosilicic acid at reduction of total energy intensity of the process and reduction of formation of difficult-to-utilize sulfuric wastes contaminated with fluorine-ion.

1 cl, 1 dwg