AlCl3 and liquid Al assisted extraction of Nd from NaCl–KCl melts via intermittent galvanostatic electrolysis

Abstract

The electrochemical reduction of Nd(III) was investigated on an inert W and a liquid Al electrode in molten NaCl–KCl eutectic salt. On both W and liquid Al electrodes, the reduction of Nd(III) ions to Nd(0) metal occurred in a single reaction step, which avoids the corrosion reaction: 2Nd(III) + Nd → 3Nd(II). Therefore, corrosion of Nd metal in this molten chloride media is not expected. The co-reduction behavior of Nd(III) and Al(III) ions was studied on a W electrode in NaCl–KCl–AlCl₃–NdCl₃ melts. Five kinds of Al–Nd intermetallic compound were detected via cyclic voltammetry and open circuit chronopotentiometry. Intermittent galvanostatic electrolysis was employed on liquid Al electrodes to extract Nd in the form of Al–Nd alloys in NaCl–KCl–NdCl₃ melts. Nd, AlNd₃, Al₂Nd, and AlNd phases were identified by X-ray diffraction (XRD). With the increase of electrolytic time, the content of Nd-rich Al–Nd intermetallic compounds in the Al–Nd alloy increased. The morphology and micro-zone chemical analysis of the deposits were characterized by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), and the Al₁₁Nd₃ phase was confirmed by EDS analysis.