Review of efficient recycling and resource utilization for rare earth molten salt electrolytic slag

With the extensive application of rare earth elements (REEs) in electronic information, new energy, aerospace and other high-tech fields, the global demand for rare earth is growing rapidly. The recovery of REEs from secondary resources has become a hot topic of research at a time when the relationship between supply and demand for rare earth is becoming increasingly tight. Currently, more than 90% of the world's rare earth metals (REMs) and alloys are produced by molten salt electrolysis, and a large amount of rare earth molten salt electrolytic slag is generated every year, which contains a high content of REEs and has a significant recovery value. This review provides a systematic summary of the various methods used by researchers in recent years to recover valuable elements from rare earth molten salt electrolytic slag, the classification of these technologies into acid and alkaline methods to their characteristics, and discussing the details of each treatment process. The Gibbs free energy of chemical reactions during the treatment of molten salt electrolytic slag was calculated based on HSC Chemical thermodynamic software to judge the theoretical feasibility of the reactions. In addition, this work presents an idea of the preparation of solid residue from electrolytic slag treatment into glass ceramics, which provides a new view for achieving the green technology of recycling and treating rare earth molten salt electrolytic slag.