Electrochemical behavior of Nd in its pyrometallurgical recovery from waste magnet

Abstract High‐purity Nd metal was recovered from waste Nd–Fe–B magnet by the molten salt electrowinning process with chemical pretreatment. X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV), chronopotentiometry (CP), and inductively coupled plasma‐atomic emission spectrometer (ICP/AES) were used to characterize the deposit and electrochemical behaviors. The results show that NdF 3 is effectively synthesized from the Nd–Fe–B magnet using HCl solution and NH 4 F. During the chemical treatment of the waste magnet, iron impurity is eliminated as a soluble [NH 4 ] 3 [FeF 6 ] complex. Electrowinning using NdF 3 in LiF molten salt shows that Nd metal is deposited from the electrolyte on the cathode at the reduction potentials ranging from −1.48 to −1.35 V (vs. W) with the concentration change of NdF 3 . The final purity of Nd metal deposit is higher than 99.78 %.