A new method for efficient recovery of rare earth resources from NdFeB waste via selective oxidation and supergravity separation

• Selective oxidation in NdFeB waste yields RE oxides , keeping iron metallic. • The selective oxidation can be achieved at 1300 °C with a carbon content of 14 wt% • Recovery of Re from NdFeB waste via selective oxidation and super-gravity. • REEs-rich slag with a rare earth content more than 82 wt% was obtained at 1320 °C. NdFeB waste is both a secondary resource rich in rare earth elements and a hazardous waste, posing significant recycling potential alongside environmental concerns. However, conventional recycling methods face significant challenges due to high separation temperatures and limited product purity. In response to these issues, this study introduces a novel recycling approach that integrates selective oxidation with a supergravity separation technique, enabling the efficient recovery of rare earth resources from NdFeB waste. Experimental results demonstrate that the addition of 14 wt% carbon powder effectively modulates the oxygen partial pressure within the system, facilitating the formation of rare earth oxides while maintaining iron in its metallic state. Following this, supergravity separation is employed within a temperature range of 1260°C to 1350°C to achieve effective segregation of iron from REEs-rich slag. The findings reveal that, when compared to the rare earth slag produced by traditional slag-iron separation methods at 1550°C, the new process at 1320°C yields a REEs-rich slag with a rare earth content increase from 67.3 wt% to 82 wt% and an improvement in the RE extraction rate from 82.7 % to 99.9 %. These results highlight the potential of this low-temperature, highly efficient process for the recovery of high-purity REEs-rich slag, offering a promising technological pathway for the environmentally sustainable recycling of NdFeB waste.