Efficient separation and recovery of neodymium through volatilization in the recycling process of spent Nd-Fe-B magnets

Abstract

Metal Pb can be used to selectively extract Nd from Nd-Fe-B magnet scraps. However, the separation of Nd from the recycled Pb–Nd alloys has become a new problem. In this work, the separation of Pb from the Pb–Nd alloys by vacuum distillation was investigated. The thermodynamic analysis based on the saturation vapor pressure and separation coefficient indicates that the component Pb is able to be separated from the Pb–Nd alloys by vacuum distillation. The effects of the distillation temperature and duration on the volatilization separation of Pb from the Pb–Nd alloy have been clarified, and the dynamic mechanism of the distillation separation was analyzed. The results show that the increase in the distillation temperature and duration can facilitate the separation between the components Pb and Nd in the Pb–Nd alloys. When the Pb-30 wt%Nd alloy was distilled at 1573 K and 0.1–5 Pa for 210 min, the removal rate of the Pb can reach more than 99.99 %, and the Nd content of the distillation residue was determined to be more than 99.41 wt%. This work provides a new and clean route for the separation and recycling of the rare earth metal Nd in the recycling process of spent Nd-Fe-B magnets.