Turning Nd-Fe-B Swarf Into High-Value Bulk Feedstocks via Sustainable Hydrogen Plasma: From Rare-Earth Oxides to Metals and Hydrides.

Rare-earth permanent magnets (REPMs) are crucial for electric vehicles, wind turbines, and other high-efficiency electric motor systems. However, their production is energy-intensive, and global recycling rates are below 0.2%. Machining swarf is the main industrial waste from REPMs production. Despite its high rare-earth elements (REEs) content (∼20 wt.%), it has received limited attention for sustainable recycling. We introduce hydrogen plasma reduction (HPR) as a new environmentally friendly method to recover REEs from REPM swarf. By tuning the hydrogen content and treatment time, we achieve phase separation into metallic Fe and a Nd2O3-rich rare-earth fraction, providing a concentrated intermediate for subsequent REPM production. The process also enables direct rare-earth hydride formation, confirming the plasma-assisted partial rare-earth metallization in the molten state. This procedure turns REPM swarf into separated, high-value, high-purity feedstock in a single, acid-free step. Against the ∼70 kg CO2-eq kg-1 footprint of conventional REPM production, this recycling route offers a pathway toward substantially lower-emission magnet production while reducing reliance on primary REE supply.