Enhanced acid leaching of rare earths from NdCeFeB magnets

Abstract

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 H[2]C[2]O[4] 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 H[2]C[2]O[4] 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.