Electrochemical Extraction of Nd from NaCl-KCl Melt by Formation of Cu-Nd Alloys

Electrochemical behavior of Nd was studied in NaCl-KCl melt on W and Cu electrodes via cyclic voltammetry and chronopotentiometry. Generally, the reduction of Nd 3+ takes place in two consecutive steps in molten chlorides, such as LiCl-CaCl 2 , LiCl-BaCl 2 , CaCl 2 -NaCl, LiCl-KCl melts. However, the reduction of Nd 3+ ions was found to be through a one-step process: Nd 3+ + 3e − → Nd. The co-reduction behavior of Nd 3+ and Cu 2+ ions and the mechanisms of alloy formation were investigated in NaCl-KCl melt on W electrodes at 988 K (715 °C). Four potential plateaus corresponding to four different kinds of Cu-Nd intermetallic compounds were detected. Cu-Nd alloys were prepared on Cu electrodes at 988 K (715 °C) and 1143 K (870 °C). At 988 K (715 °C), Cu 5 Nd phase was identified by X-ray diffraction. The morphology and micro-zone chemical analysis of the alloys were characterized by scanning electron microscopy equipped with energy-dispersive spectrometry. The alloy film was observed on the Cu electrodes. Moreover, at 1143 K (870 °C), a globate bulk Cu-Nd alloy with Cu 5 Nd, Cu 4 Nd, Cu 2 Nd, CuNd, and Cu phases, as liquid in the melt, was obtained at the bottom of the crucible.