METHOD FOR PRODUCING HIGH-PURITY LITHIUM HYDROXIDE MONOHYDRATE FROM MATERIALS CONTAINING LITHIUM CARBONATE OR LITHIUM CHLORIDE Russian patent published in 2021 - IPC C01D15/02 C01D15/04 C25B1/34 

FIELD: chemical industry.

SUBSTANCE: to obtain high-purity lithium hydroxide monohydrate, a solution of lithium chloride is prepared by dissolving materials containing lithium chloride in water or materials containing lithium carbonate in hydrochloric acid. The lithium chloride solution is purified from calcium and magnesium using a lithium hydroxide solution, and the solid phase is separated from the lithium chloride solution. The electrochemical conversion of the purified lithium chloride solution to the lithium hydroxide solution is carried out by membrane electrolysis. The anolyte circulating in the anode circuit of the membrane electrolysis plant is acidified with hydrochloric acid to pH of 1-3. The concentration of lithium chloride in the anolyte is maintained at the level of 50-300 g/l, and the concentration of the resulting lithium hydroxide solution is in the range of 40-80 g/l. The alkali solution formed in the electrolyzer is partially removed from the process and sent to the evaporation stage for the crystallization of lithium hydroxide monohydrate. The pulp of lithium hydroxide monohydrate is centrifuged, the resulting crystals are sent for washing, dehydration and drying to obtain the final product.

EFFECT: invention makes it possible to involve materials containing lithium carbonate or lithium chloride in the production to produce lithium hydroxide monohydrate of a high degree of purity using minimum amount of reagents, eliminating the waste formation.

5 cl, 3 ex