Extraction of rare earth, lithium and fluorine by acid leaching of roasted product of rare earth electrolytic molten salt slag

Rare earth electrolytic molten salt slag was activated by coordinated roasting with calcium oxide and aluminum sulfate, and sulfuric acid leaching was used to extract the rare earth, lithium, and fluorine in the slag. The effects of different acid leaching conditions on their leaching rates were investigated. For the leachate under the optimal acid leaching conditions, the rare earth compound salt was precipitated with sodium sulfate to realize the separation of rare earth. The results showed that the optimal acid leaching condition was sulfuric acid concentration 4 mol/L, liquid-solid volume ratio 10:1 (unit: mL/g), leaching temperature 90℃, leaching time 4 h. The leaching rates of gadolinium, lithium, and fluorine were 95.83%, 96.55%, 93.06%, 95.52% and 94.85%, respectively. The precipitation purity of rare earth complex sulfate precipitation was high, and the yield of rare earth could reach over 99.3%. The method could be used to recover rare earth, lithium, and fluorine from rare earth molten salt electrolysis slag and was of great significance for improving its utilization of all components.