[P1] RE-Fe-B Magnets

[P1-30] Magnetic properties and recovery rate of recycling hundred-kilogram-scale NdFeB sintered magnets with the improved short-loop recycling process

*Chih-Chieh Mo¹, Chih-Cheng Kuan¹, Yung-Hsiang Wang¹ (1. SPIN Sustainable Energy Industry Corporation, Hsinchu Country 30352, Taiwan (Taiwan))

Keywords:

NdFeB Magnet Recycling,Short-Loop Recycling

Recently, the recycling and regeneration of rare-earth magnets has become a significant environmental issue. In this work, the improved short-loop recycling method is used for the recovery and regeneration of hundred-kilogram-scale waste NdFeB sintered magnets in order to enhance the recovery rate. The traditional short-loop recycling for waste sintered Nd-Fe-B magnets adopted hydrogen decrepitation to break NdFeB magnets into powders, followed by separation from the sheet-like electroplated layer. However, some magnet remains adhered by an electroplated layer. If the NdFeB magnets attached to the electroplated layer are discarded along with the layer, the recovery rate of NdFeB material will be reduced. In this work, a rolling process is tried to detach and collect the adhered NdFeB material from the electroplated layer in order to improve the recovery rate of NdFeB magnets in the following 3 cases. For the first case of the discarded magnets applied in VCM of HDD, magnetic properties of recycled magnets made by a traditional method are (BH)max = 47.1 MGOe, iHc = 15.3 kOe, with a lower recovery rate of 64.1%. After adding a rolling process, magnetic properties of the recycled regenerated magnets are similar, that is (BH)max = 47.3 MGOe, iHc = 15.4 kOe. Most importantly, the recovery rate is significantly increased to 82.2%. Besides, For the discarded magnets in wind turbines, magnetic properties of recycled magnets made by using traditional method are (BH)max = 39.4 MGOe, iHc = 17.8 kOe, with a recovery rate of 96.0%. By the improved process, magnetic properties are also similar: (BH)max = 39.0 MGOe, iHc = 17.9 kOe, and a recovery rate could be achieved to 99.1%. In the final case of discarded magnets in HEV motor, similar magnetic properties is found. A recovery rate is also increased effectively from 87.0% to 95.2%. The results of this work indicate the introduction of a rolling process could significantly improve the recovery rate of the recycled NdFeB sintered magnets and provide important information for mass production of the recycled NdFeB sintered magnets.