Selective Leaching Process for Neodymium Recovery from Scrap Nd-Fe-B Magnet

Neodymium-iron-boron (Nd-Fe-B) magnets were most widely applied to permanent magnetic products in the world due to their high magnetic force. The increasing growth of scrap Nd-Fe-B magnets resulted in disposal problems and the reduction of neodymium (Nd) valuable resources. In this study, we developed a simple hydrometallurgical precipitation process with pH adjustment to separate and recover Nd 100 pct recovery from scrap Nd-Fe-B magnets. Several physical and chemical methods such as demagnetization, grinding, screening, and leaching processes were also adopted to investigate the recovery of Nd and other metals from scrap Nd-Fe-B magnets. The leaching process was carried out with four leaching reagents such as NaOH, HCl, HNO3, and H2SO4. Batch studies were also conducted to optimize the leaching operating conditions with respect to leaching time, concentration of leaching reagent, temperature, and solid/liquid ratio for both HCl and H2SO4 leaching reagents. Nd was successfully separated and recovered with 75.41 wt pct from optimized H2SO4 leaching solution through precipitation. Further, the purity and weight percentage of the obtained Nd product was analyzed using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) analysis. An X-ray diffraction (XRD) study confirmed the obtained product of Nd was in the form of NdOOH and Nd(OH)(3).