SODIUM HYDROSULFITE PRODUCTION PROCESS Russian patent published in 2006 - IPC C01B17/32 

FIELD: production of inorganic compounds.

SUBSTANCE: sodium hydrosulfite, which is starting material in production of soda ash, polysulfide plastics, in pulp-and-paper industry, in ore mining and processing enterprises, and in leather industry, is obtained by reaction of sodium sulfide with hydrogen sulfide. The former is preliminarily obtained through reduction of sodium sulfate in presence of calcium sulfate at molar ratio Na₂SO₄:CaSO₄ equal to 1:(0.5÷1.25), after which resulting melt is leached and filtered. Filtrate containing sodium sulfide is brought into interaction with hydrogen sulfide formed when filtration slime is treated with hydrochloric acid solution followed by separation of resulting calcium chloride solution from slime, while excess hydrogen sulfide is absorbed by alkali absorbent.

EFFECT: reduced production cost due to utilization of inexpensive and accessible raw material and additionally producing commercially important calcium chloride.

2 cl, 3 ex