Enhanced acid leaching of rare earths from NdCeFeB magnets

Development of the effective technology for recovery of critical rare-earth elements (REEs) from end-of-life permanent magnets is one of the important technological challenges. In this study, chemical and electrochemical leaching of NdCeFeB magnets was investigated in 0.5 mol/L sulfuric acid containing varying concentration of oxalic acid. The influence of H2C2O4 concentration on leaching efficiency and morphological properties of the NdCeFeB surface, as well as on the chemical composition and ζ-potential of the oxalate precipitate particles was discussed. Efficient separation of REEs can be achieved at H2C2O4 concentrations of 0.05–0.20 mol/L and the maximum REE purity was 97.2%. In electrochemical leaching, the leaching rate was substantially higher than in chemical leaching, where blocking of the magnet surface by precipitate layer was observed.