Method for producing highly pure battery grade lithium carbonate by using lithium sulfate solution
The invention discloses a method for producing highly pure battery grade lithium carbonate by using a lithium sulfate solution. The method comprises the following steps: 1, carrying out lithium sulfate solution salt crystallization refining: adding sodium hydroxide to the lithium sulfate solution used as a raw material, cooling to precipitate sodium sulfate decahydrate, separating out sodium sulfate decahydrate, and complexing calcium, magnesium and other impurities in the salt crystallized lithium solution by using EDTA; 2, carbonizing and precipitating lithium: carrying out a carbonizing and lithium precipitating reaction at a relatively constant high temperature to obtain the highly pure battery grade lithium carbonate product and a lithium precipitation mother liquor; and 3, recovering the mother liquor: neutralizing the generated lithium precipitation mother liquor with sulfuric acid, concentrating the neutralized lithium precipitation mother liquor, and returning the concentrated mother liquor to the lithium sulfate solution raw material for recycling. The battery grade lithium carbonate produced through the method is highly pure, and lithium carbonate produced by using the lithium sulfate solution recovered through the treatment technology of the lithium precipitation mother liquor still is highly pure battery grade lithium carbonate, so all of the produced lithium carbonate is the highly pure battery grade lithium carbonate.