Systemic and Direct Production of Battery-Grade Lithium Carbonate from a Saline Lake

A process was developed to produce battery-grade lithium carbonate from the Damxungcuo saline lake, Tibet. A two-stage Li 2 CO 3 precipitation was adopted in a hydrometallurgical process to remove impurities. First, industrial grade Li 2 CO 3 was obtained by removing Fe 3+, Mg 2+, and Ca 2+ from a liquor containing lithium. Second, industrial grade Li 2 CO 3 was treated by CO 2 to get the more soluble bicarbonates. EDTA-Li (lithium 2-carboxyhydrazine-1,1,2-tricarboxylate) was added to chelate Ca 2+ and Mg 2+ . The decomposition of LiHCO 3 produced insoluble Li 2 CO 3 at 85 °C. The final precipitation yielded a high purity (99.6%) and homogeneous Li 2 CO 3 . Some factors affecting the production efficiency were investigated. The results showed that an L/S mass ratio of 30:1 favored the formation of a Li 2 CO 3 slurry; a molar ratio of EDTA-Li to (Ca+Mg) 1.05:1 and hot water washing precipitate (L/S mass ratio 1:1) promoted ions removal; a cyclic use of filtrate improved the recovery of lithium.