Recovery and separation of rare earth elements by molten salt electrolysis

With the increasing demand of rare earth metals in functional materials, recovery of rare earth elements (REEs) from secondary resources has become important for the green economy transition. Molten salt electrolysis has the advantages of low water consumption and low hazardous waste during REE recovery. This review systematically summarizes the separation and electroextraction of REEs on various reactive electrodes in different molten salts. It also highlights the relationship between the formed alloy phases and electrodeposition parameters, including applied potential, current, and ion concentration. Moreover, the feasibility of using LiF-NaF-KF electrolyte to recover REEs is evaluated through thermodynamic analysis. Problems related to REE separation/recovery the choice of electrolyte are discussed in detail to realize the low-energy and high current efficiency of practical applications.