Neodymium electrowinning into copper-neodymium alloys by mixed oxide reduction in molten fluoride media

Abstract : The possibility of neodymium electrowinning from neodymium oxide using a reducing agent (RA) produced in-situ by solvent reduction was investigated in molten LiF⿿CaF2⿿Li2O between 900 °C and 1040 °C. Nd2O3 galvanostatic electrolyses were performed and reaction products were analyzed by SEM, XRD and electron-probe microscopy. Metallic neodymium was not directly obtained, due to several limitations for Nd2O3 reduction: low electrical conductivity, unfavourable Pilling⿿Bedworth coefficient and formation of a dense insulating CaO layer on the sample surface. Consequently, the reduction of a pellet made of a neodymium oxide-metallic oxide mixture was carried out as an alternative pathway. Nd2O3-CuO reduction led to metallic neodymium production in the form of liquid Cu-Nd alloys. A reaction mechanism was proposed based on these experimental results: