Bayer Aktiengesellschaft

Wolf Becker

Wolfgang Weiss

Heinz Jonas

Recovery of hydrofluoric acid from aqueous fluosilicic acid by treating said aqueous fluosilicic acid at a temperature of from 100.degree. to 300.degree.C. and under a pressure of from 3 to 80 atmospheres and separating resulting hydrogen fluoride containing aqueous phase and silicon tetrafluoride containing gaseous phase and optionally hydrolyzing the silicon tetrafluoride containing gaseous phase in aqueous medium and recycling the aqueous fluosilicic acid to the process as starting material.

Recovery of hydrofluoric acid from aqueous fluosilicic acid

A process which comprises reacting at a temperature above 100.degree.C. a metal oxide, hydroxide or a mixture thereof with aqueous fluosilicic acid, said fluosilicic acid having a concentration of about 10 to 45% by weight, to form gaseous silicon tetrafluoride and the corresponding metal fluoride and recovering said metal fluoride from the reaction medium.

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Cologne, Germany

Wolf Becker