METHOD OF PRODUCTION OF HYDROFLUORIC ACID AND SILICON DIOXIDE Russian patent published in 2001 - IPC

FIELD: methods of production of hydrofluoric acid and silicon dioxide; processing of industrial gases containing silicon tetrachloride and hydrogen fluoride. SUBSTANCE: gas to be processed is subjected to plasma chemical hydrolysis in flow of vapor-and-water plasma; gas delivered to hydrolysis stage has temperature below dew point of hydrogen fluoride contained in it; hydrolysis is performed at temperature of 2000 to 2500 K; hydrolysis products are subjected to hardening at rate of 10³-10⁴ K/s, silicon dioxide is separated and hydrofluoric acid is condensed. Starting flow of vapor-and-water plasma before mixing with gas to be processed has average mass temperature of 2600- 3000 K. Hydrofluoric acid thus produced contains up to 50 mas. % of HF; it is free from admixtures of nitric acid; silicon dioxide is just ultra-dispersed powder at amorphous structure of tridynamite and bulk density of 0.05-0.07 g/cu.cm. EFFECT: enhanced efficiency. 2 cl, 2 tbl