METHOD OF PRODUCING SODA-SULPHATE MIXTURE FROM RECYCLED SODA-SULPHATE SOLUTIONS OF GAS CLEANING OF ALUMINIUM ELECTROLYZERS Russian patent published in 2024 - IPC C01D5/00 C01D7/00 C02F103/16 B01D53/78 

FIELD: non-ferrous metallurgy.

SUBSTANCE: invention can be used to obtain commercial products from wastes formed during wet gas cleaning of exhaust gases from residues of hydrogen fluoride and sulphur dioxide from electrolysis buildings of aluminium production. Method involves defluorination of the solution with extraction of secondary cryolite, its further clarification with a reagent to reduce suspension of fluorides and gas cleaning sludge to obtain a clarified solution. Evaporation of the clarified solution until a solid phase appears and the obtained pulp of the soda-sulphate mixture is filtered. Clarification is carried out with a synthetic flocculant, and filtration of the soda-sulphate mixture pulp is combined with its washing with cold process water with separation of the filtrate and sediment of the soda-sulphate mixture, which is sent for drying, wherein the dried residue of the soda-sulphate mixture is ground to a size of minus 200 mcm to increase the whiteness factor.

EFFECT: obtaining a soda-sulphate mixture with high whiteness coefficient and low yellowness index.

5 cl, 1 dwg, 3 tbl