METHOD OF RECYCLING WASTE GASES, FORMED IN PROCESS OF OBTAINING PYROGENIC SILICON DIOXIDE BY HIGH-TEMPERATURE HYDROLYSIS OF SILICON CHLORIDES Russian patent published in 2012 - IPC C01B33/12 C01B33/18 B01D49/00 

FIELD: chemistry.

SUBSTANCE: invention relates to field of technology of inorganic substances, in particular to methods of recycling of waste gases, formed in process of obtaining pyrogenic silicon dioxide by high-temperature hydrolysis of silicon chlorides. Method of waste gas recycling includes purification of waste gases, containing hydrogen chloride, water vapour, chlorine and silicon dioxide, from hard suspension of silicon dioxide, absorption of hydrogen chloride, obtaining hydrochloric acid, selection and filtration of waste circulating suspension. Purification from fine-grained suspended solids of silicon dioxide is performed by irrigation with circulating flows of silicon dioxide suspension in concentrated ≥31.5 wt % HCl hydrochloric acid. Waste suspension of silicon dioxide in hydrochloric acid with content of silicon dioxide 80-120 g/dm³ is taken from the contour of the first scrubber for filtration. Filtrate is passed into the flow of circulating suspension into the second scrubber, in whose contour concentration of silicon dioxide suspension in hydrochloric acid is supported to 1-10 g/dm³. Consumption of circulating suspension from the contour of the first scrubber is compensated with suspension from the flow of circulating suspension of the second scrubber.

EFFECT: increased efficiency of purification of waste gases from production of pyrogenic silicon dioxide from hard phase, reduction of loss of concentrated hydrochloric acid and consumption of reagent for neutralisation during waste suspension recycling.

3 cl, 1 dwg, 1 ex