Recovery of Rare Earth from Nd-Fe-B Magnets by Chlorination

In order to obtain fundamental data for developing an efficient recovery process of rare earth elements from Nd-Fe-B magnets, the release behavior of Nd, Pr and elements was investigated under the conditions of heating rate of 30 degrees C/min and terminal temperatures from 100 to 1000 degrees C in a Cl(2) gas stream. Fe and B volatilizedin the low temperature region, while Nd and Pr were concentratedin the solid phase by the chlorination. Nd-Fe-B samples werepre-oxidized by heating at 500 degrees C in air to prevent spontaneous combustion of the fine magnet powder. While Fe and Co in the oxidized magnet were volatilized during the chlorination, the rare earth elements and B mostly remained in the solid phase as water-insoluble forms. When carbon and SiC powders were added to the oxidized sample, Fe, Co and B were completely volatilized at 1000 degrees C by carbochlorination. Nd and Pr were concentrated in the residue of the oxidized magnet sample. It was also found that Nd and Pr could be selectively recovered by leaching with water from the residue, because these elements formed chlorides by the carbochlorination.