Recovering and Purifying Neodymium and Dysprosium from Simulated Leaching Solution of Spent NdFeB Magnets via Ion Exchange Processes

As critical rare earth elements (REEs), the industrial demand for neodymium (Nd) and dysprosium (Dy) increases rapidly due to their specific physical and chemical properties. Recycling these REEs from secondary resources such as spent NdFeB magnetic materials is an efficient approach for sustainable production. However, the separation of neodymium and dysprosium in aqueous solutions is an arduous task because of their close chemical properties. Recovering and purifying neodymium and dysprosium from a simulated leaching solution of spent NdFeB magnets were conducted by employing selective ion exchange resins. It was found that Purolite S950 PLUS resin functionalized with aminophosphonic groups demonstrated selective adsorption toward Nd3+ and Dy3+ while maintaining low affinity for Fe(II) at low pH (i.e., 0.65), which could realize efficient iron removal from the solution. Purolite MTX7010 resin impregnated with di-(2-ethylhexyl) phosphoric acid (D2EHPA) had a strong adsorption preference for Dy3+ over Nd3+, which is highly suitable for Dy separation from their mixed solutions under optimized conditions. By employing a multistage adsorption–elution process analogous to distillation, a prospective purity of 98.51% for Dy and a purity over 99.90% for Nd were realized with high metal recoveries from the synthetic leaching solution of spent NdFeB magnets. This research demonstrates that recovery and purification of single REEs from leaching solutions containing mixed REEs and other metals can be achieved with selective resin adsorption processes analogous to distillation despite large concentration differences in the metals in the solutions, which presents a new approach.