Study of Neodymium Extraction in Molten Fluorides by Electrochemical Co-Reduction with Aluminium

Abstract

This work concerns the co-deposition process of Al-Nd alloys in LiF-CaF2 medium (79-21% mol.) on tungsten electrode at 860 °C using electrochemical techniques: cyclic and square wave voltammetries and potentiostatic electrolyses. Specific peaks of Al-Nd alloys formation were observed in cyclic voltammograms between the reduction waves of Nd(III) and Al(III), in a fluoride melt containing neodymium and aluminium ions. The difference of potential measured between solvent reduction and the alloys formation allows expecting an extraction efficiency of 99.99% by the use of the co-reduction process. The intermetallic compounds (Al11Nd3, Al3Nd, AlNd2 and AlNd3) were obtained and characterised by Scanning Electron Microscopy with EDS probe. The validity of the process was tested by carrying neodymium extraction in the form of Al-Nd alloy; the extraction efficiency was more than 95%.