Highly Efficient and Precise Electrolysis Separation of Dysprosium from Neodymium for Magnet Scrap Recycling in Molten Salt

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Because the use of Dy-containing heat-resistant Nd magnets for electric vehicles is dramatically increasing, an environmentally friendly recycling method for rare-earth (RE) elements with high-precision separation of Dy and Nd from end-of-life magnets is necessary to realize a sustainable society in the future. In this study, we developed a novel method for the separation and recycling of RE by electrochemical manufacturing of RE–Ni alloys in molten salt, which has a high processing rate and high Dy/Nd separation ratio. The experiments were conducted in the molten CaCl 2 –NdCl 3 (1.0 mol %)–DyCl 3 (1.0 mol %) system at 1123 K. RE–Ni alloys were electrochemically formed on Ni cathodes at various potentials, and both the alloy formation rate and the Dy/Nd ratio were investigated. We observed a specific phenomenon: a high Dy/Nd ratio and a high alloy formation rate were obtained simultaneously by adding a small amount of F – to the system, which enables highly efficient and precise RE separation. In previous studies, it was difficult to obtain high values for these two factors simultaneously. The reason for this specific phenomenon is explained by the change in the coordination state of RE 3+ .