Sustainable Mining and Metallurgy

Aiming at the problems of long recovery process, high lithium loss rate and low purity in the traditional method of lithium recovery from waste ternary power battery black powder, a process of priority extraction of lithium by sulfation roasting was proposed. In this paper, the thermodynamic feasibility of lithium extraction by sulfation roasting was analyzed. The effects of different sulfate, concentrated sulfuric acid addition, calcination temperature and calcination time on lithium extraction were studied. The results of sulfation roasting experiments of different sulfates show that the lithium yield is about 95% when concentrated sulfuric acid, sodium bisulfate and ammonium sulfate are used for sulfation roasting. The roasted material obtained by adding sodium bisulfate is harder; the roasted material obtained by adding concentrated sulfuric acid is fluffy and honeycomb-like; the material after roasting with ammonium sulfate is powder, which is easy to break, but will produce ammonia gas. Lithium phosphate can not be obtained by roasting with the same amount of sodium sulfate, so concentrated sulfuric acid is selected for sulfation roasting. The optimum conditions for the preferential extraction of lithium are as follows: the amount of concentrated sulfuric acid is 105% of the theoretical amount, the calcination temperature is 600℃, and the calcination time is 2h. Under these conditions, the lithium yield can be as high as 95.2%. The prepared lithium carbonate and lithium phosphate have low impurity concentration and high purity.