Selective electrodeposition of dysprosium in LiCl-KCl-GdCl3-DyCl3 melts at magnesium electrodes: Application to separation of nuclear wastes

The electrochemical behaviour and extraction efficiency of DyCl3 and GdCl3 solutions were studied by cyclic voltammetry, square wave voltammetry and open-circuit chronopotentiometry in the eutectic LiCl-KCl at 773 K using inert and reactive electrodes, i.e. W and Mg, respectively. On W and Mg electrodes, Dy(III) ions are reduced to metallic dysprosium through two consecutive steps. The selective electrodepositing of dysprosium in a form of Mg-Dy alloys can be easier than that in a pure metallic form, without reduction of the extraction yield. Potentiostatic electrolysis experiments were performed to extract Dy from GdCl3 and DyCl3 mixtures at magnesium electrodes. XRD patterns of deposit indicated that Mg3Dy phase was formed. Scanning electron microscope (SEM) images with Energy dispersive X-ray Spectroscopy (EDS) showed the grain size was refined with a greater content of Dy in alloys