METHOD OF CRYSTALLIZATION OF SODIUM SULPHATE FROM GAS CLEANING OF ALUMINUM PRODUCTION Russian patent published in 2019 - IPC C01D5/00 C01B9/08 B01D9/02 

FIELD: metallurgy.

SUBSTANCE: invention can be used in metallurgy. Method of crystallization of sodium sulfate from the gas cleaning solutions of the electrolytic production of aluminum involves saturating the gas cleaning solutions with sodium sulfate prior to the crystallization process, separating and dewatering the resulting precipitate. Crystallization process is carried out by injection of sodium sulfate in vacuum crystallizers to a concentration of 40–120 g/l while creating a vacuum of 0.3–0.5 at and maintaining the temperature from 50 to 60 °C. Concentrated solution is incubated for 20–25 minutes with the formation of double salt NaF⋅Na₂SO₄, that is thickened and filtered.

EFFECT: invention makes it possible to increase the completeness of the release of sodium sulfate from waste soda solutions of gas cleaning electrolytic production of aluminum, to reduce the loss of sodium sulfate and sodium fluoride in the form of deposits in pipelines and apparatus.

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