Recovery of rare earth elements from permanent magnet scraps by pyrometallurgical process

In order to recover valuable rare earth elements from Nd–Fe–B permanent magnet scraps, a high-temperature pyrometallurgical process was developed in this work. The magnet scraps were first pulverized and oxidized at 1000 °C in normal atmosphere. The oxidized mixtures were then selectively reduced by carbon in the temperature range of 1400–1550 °C. In this way, the rare earth elements were extracted to the form of oxides, whereas Fe and B were separated to metal phase. For improving the purity of rare earth oxides, the effects of temperature and reaction time on the reduction of B₂O₃ in oxide phase were investigated. It is found that increasing reaction temperature and extending reaction time will help the reduction of B₂O₃ contents in rare earth oxide phase. Almost all rare earth elements can be enriched in the oxide phase with the highest purity of 95 %.