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 degrees C in normal atmosphere. The oxidized mixtures were then selectively reduced by carbon in the temperature range of 1400-1550 degrees 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 %.

Automated summary

A high-temperature pyrometallurgical process was developed to recover valuable rare earth elements from Nd-Fe-B permanent magnet scraps. By pulverizing and oxidizing the magnet scraps, the rare earth elements were extracted as oxides while separating Fe and B as metal phase. Temperature and reaction time were found to be crucial for improving the purity of rare earth oxides.