METHOD FOR OBTAINING CRYSTALLINE SODIUM SULFATE FROM LIQUID WASTE OF ELECTROLYTIC ALUMINUM PRODUCTION Russian patent published in 2021 - IPC C01D5/00 C01D5/16 C01D5/18 B01D9/02 

FIELD: chemical industry.

SUBSTANCE: invention relates to the electrolytic production of aluminum and in particular to the technology for processing liquid waste generated in the purification of gases, and can be used in the crystallization of sodium sulfate from solutions of gas purification of electrolytic aluminum production. The method involves cooling the clarified sulfate-containing solution, pre-purified from carbon-containing suspensions, initially to a temperature not less than 10°C in a mixer tank 1, taken outside the building, in the intensive continuous mixing mode, with the formation of finely dispersed sodium sulfate crystals, and then cooling to a temperature of +4-(-1)°C in a thickener separator 3, placed inside the building, in the intensive continuous mixing mode, by pumping cold atmospheric air through the entire volume of the solution under pressure, with the formation of large crystals of sodium sulfate transported for filtration 6 and drying, and the desulfurized solution directed to the reactor for cooking secondary regenerative cryolite.

EFFECT: reduction of solution cooling time and energy costs in the process of crystallization of sodium sulfate, increase in the productivity of the process, obtaining a marketable product with the content of the main substance, crystalline sodium sulfate, from 95.3 to 96.9, wt. % , and the insignificant content of impurities: fluorine less than 0.4, wt. %, solid residue no more than 0.9, wt. %.

4 cl, 1 dwg, 3 tbl, 2 ex