Work

Sustainable recycling of end-of-life Nd-Fe-B permanent magnets through hydrogen based plasma reduction

Year: 2026

Type: preprint

Abstract: Nd–Fe–B permanent magnets are essential for multiple energy, mobility, safety, and decarbonization-related technologies, yet rising demand, environmental impacts, and limited sustainable recycling options increase their material criticality. Herein, we propose Hydrogen Plasma Smelting Reduction (HPSR) as a novel composition-independent recycling strategy, applied for the first time to end-of-life (EoL) Nd–Fe–B magnets, enabling the universal treatment of mixed-quality magnetic scrap. The maximum oxygen content reduction of 66% is realized within tHPSR = 2.5 min of processing, reaching ~810 ppm while preserving the overall alloy stoichiometry, including critical rare-earth elements (REEs = Nd, Pr, and Dy). HPSRrecycled powders present higher remanent polarization (Jr = 0.54 – 0.66 T), intrinsic coercivity (Hcj = 1.02 – 1.45 T), maximum energy product (BH)max = 53.5 – 72.4 kJ m-3) and improved thermal stability, surpassing the magnetic properties of the starting scrap material without the addition of primary elements (Jr = 0.56; Hcj = 0.93 T, (BH)max = 46.5 kJ m-3). Under intentional contamination from the coating material (Ni), the reduction in the overall extrinsic magnetic properties is observed, as expected. These findings establish a foundation for the first fully sustainable and composition-independent so-called intermediate recycling loop for mixedquality REE-based magnet waste.

Source: ChemRxiv

DOI: 10.26434/chemrxiv.15008192/v1