Electroextraction of samarium from Sm2O3 in chloride melts

This work firstly presents an electrochemical study of samarium extraction from Sm2O3 in the LiCl-KCl-AlCl3 melts. Gibbs energy calculation shows that AlCl3 can favorably chloridize Sm2O3 and release Sm3+ ions under this condition. The electrochemical behaviors of Al3+, Sm3+ and the mechanisms of alloy formation were investigated using a series of electrochemical techniques on a molybdenum electrode. Two typical signals corresponding to different kinds of Sm-Al alloys were observed in the cyclic voltammetry and square wave voltammetry. The transformation process from one AlxSmy biphasic phase to another was revealed by open circuit chronopotentiometry. The Sm-Al alloy samples were prepared by potentiostatic and galvanostatic electrolysis on an aluminium electrode. SEM-EDS and XRD analysis demonstrated that a layer of SmAl3 can be formed by potentiostatic electrolyses, whereas two kinds of intermetallic compounds of SmAl4 and SmAl3 can be formed by galvanostatic electrolysis. In addition, the electroextracti on of samarium by co-reduction with Al3+ on the aluminium electrode has been performed with extraction efficiency of 88.7% for potentiostatic electrolysis and 94% for galvanostatic electrolysis, respectively. (C) 2014 Elsevier Ltd. All rights reserved.