Preparation method of lithium carbonate from lithium-ion secondary battery recovered material
View Patent ↗A preparation method of lithium carbonate, in recovering valuable resources of a lithium-ion battery, reducing impurities from lithium carbonate, having a pretreatment process, comprising: a first step cleaning an organic phase containing nickel and lithium prepared by a solvent extraction by use of a sulfuric acid solution containing nickel and enriching lithium in the cleaning solution; a second step extracting a residual nickel only by an organic solvent from a post-cleaning solution in which the lithium is enriched; and a third step controlling pH of the post-extraction solution containing the lithium by ammonia water or lithium hydroxide.
1. A preparation method of lithium carbonate, comprising:
a first step of providing a cleaning solution, and extracting nickel and lithium into an organic phase by solvent extraction, cleaning the organic phase with a sulfuric acid cleaning solution containing nickel, wherein lithium in the organic phase is transferred to the sulfuric acid cleaning solution, thereby obtaining a post-cleaning solution where lithium is enriched;
a second step of extracting residual nickel from the post-cleaning solution obtained in the first step by solvent extraction with an organic solvent from the post-cleaning solution, while controlling a pH of the post-cleaning solution by adding an alkaline agent; and
a third step of precipitating and recovering lithium carbonate by injecting carbon dioxide gas or adding other carbonation agents, while controlling the pH of the post-cleaning solution by adding a second alkaline agent, thereby recovering lithium carbonate.
2. The preparation method of claim 1 , further comprising a fourth step of cleaning the recovered lithium carbonate.
3. The preparation method of claim 1 , wherein the organic solvent used in the second step is a carboxylic acid system extract agent.
4. The preparation method of claim 1 , wherein an equilibrium pH of the post-cleaning solution in the first step is 2 to 4.
5. The preparation method of claim 1 , wherein the pH of the post-cleaning solution in the third step is controlled to 8 to 11.
6. The preparation method of claim 2 , wherein the lithium carbonate is cleaned at 60 to 95° C. in the fourth step.
7. The preparation method of claim 1 , wherein a concentration of sodium in the recovered lithium carbonate is less or equal to 700 mass ppm.
8. The preparation method of claim 1 , wherein the alkaline agent used in the second step is aqueous ammonia or lithium hydroxide.