Selective Recovery of Rare Earth Elements from Dy containing NdFeB Magnets by Chlorination

To develop an effective recovery process of rare earth metals from Dy containing Nd2Fe14B magnets (NdFeB-Dy), the release behavior of rare earth metals (Nd and Dy) and coexisting elements (Fe, B, Co, Cu, Zr) from the magnets during chlorination are investigated under the conditions at rate of 30 degrees C/min and predetermined temperatures from 100 to 1000 degrees C in a Cl-2 gas stream. Although coexisting elements volatilize from NdFeB-Dy in the low temperature region, Nd and Dy condense in the chlorination residue obtained up to 1000 degrees C. NdFeB-Dy is preoxidized by heat treatment up 350, 600, and 900 degrees C in air to represent demagnetized and decarbonized samples. While Fe, Co, and Cu in oxidized sample volatilize during chlorination, Zr and B remain with rare earth metals in the oxidation samples during chlorination temperature up to 1000 degrees C. When carbon is added to the oxidation samples, all of the elements, except Nd and Dy, volatilize until 1000 degrees C, thus the rare earth chlorides can be concentrated in the residue after carbochlorination. The rare earth chlorides in the chlorination residues containing carbon can be modified by heat treatment up to 1000 degrees C under steam to recover rare earth oxides.