Neodymium recovery from scrap magnet using ammonium persulfate
This study proposes a novel leaching methodology to recover neodymium from scrap magnet using ammonium persulfate ((NH4)2S2O8) solutions. The NdFeB magnets from obsolete Hard-Disk-Drives were physically treated by thermal demagnetization (400 °C, 45 min) and mechanical crushing (< 420 μm). The chemical composition of the ground sample was Nd: 31.5 wt%, Fe: 64.8 wt%, Co: 1.9 wt%, Ni: 0.6 wt%. Diagrams of equilibrium phases (Eh vs. pH) were designed to determine the predominance of the formed species in the (NH4)2S2O8 system.