Process for the preparation of crystalline potassium tantalum fluoride

摘要

Potassium tantalum fluoride substantially free from compounds of silicon and niobium is prepared from a crude tantalum-niobium salt solution by use of aqueous hydrofluoric acid having a dissolved content of a silicon compound by mixing the salt solution with a water-insoluble organic solvent for said salts; extracting the organic phase with aqueous medium; mixing the organic phase with silicon-contaminated aqueous hydrofluoric acid; mixing the organic phase with a hot silicon-free solution of an ionizable potassium compound, and separating and cooling the aqueous phase thereby precipitating potassium tantalum fluoride. The phases are separated between steps.