Challenges in electrolysis of neodymium in chloride melts at 500 °C

This work is concerned with the electrolysis of neodymium chloride produced in hydro- or pyrometallurgical recycling processes of NdFeB magnets. Due to the high temperature, the energy consumption is huge in today's industrial reduction processes. In a LiCl-KCl electrolyte with approx. 2 wt% NdCl3, neodymium can be electrolyzed at a moderate temperature of 500 °C. The deposition of a solid layer of neodymium from similar electrolytes has already been described for very small amounts of deposited neodymium. In continuing electrolysis, instead of a thick layer of neodymium at the cathode, fine neodymium crystals were found inside the electrolyte. The results were attributed to a change in reaction mechanism from electrodeposition to the disproportionation of intermediate Nd2+.