Selective Extraction of Iron and Rare‐Earth Elements From Neodymium–Iron–Boron Leaching Residues Using Magnetic Separation and Sulfation Roasting

Neodymium–iron–boron (NdFeB) leaching residues (NLR) was a major byproduct generated during the recycling of end‐of‐life NdFeB magnets. Owing to its nearly 50 wt% Fe content, NLR represented a promising secondary source of iron. However, its complex composition, together with the energy‐intensive nature of conventional recycling methods, hindered the efficient recovery of valuable metals. This study employed a novel strategy that integrated biochar‐mediated reduction with magnetic separation to recover iron‐rich concentrates (IRC) from NLR. The Fe content in IRC exceeded 58 wt%, which met the requirements for direct utilization in blast‐furnace ironmaking. The separation efficacy was demonstrated by a high Fe recovery of ~95.61%, and an effective rejection of nonmagnetic by ~77.82% into the tailings. Subsequent sulfation roasting and leaching of IRC under optimal conditions achieved high extraction efficiencies (Fe: ~97.7%, Nd: ~98.2%, Pr: ~95.9%, Al: ~81.8%). Importantly, biochar‐mediated prereduction enhanced the reactivity of iron oxides, thereby lowering both acid consumption and reaction temperature. This integrated strategy provided a closed‐loop valorization pathway for NLR, enabling the simultaneous recovery of Fe and critical metals with minimal energy input. By converting hazardous waste into high‐value products, the approach offered both economic viability and environmental sustainability within the rare‐earth circular economy.