Spatial distribution of CeBi2 in Bi-Ce alloy facilitating density-based separation between actinides and lanthanides

Abstract

This study presents the spatial distribution of CeBi2 in Bi-Ce alloys formed in various conditions to investigate density-based separation using liquid Bi between the intermetallic compound of actinides and lanthanides in used molten salt from pyroprocessing. It was experimentally identified that CeBi2 clearly formed and floated at the top of Bi-Ce alloy. Four Bi-Ce alloys were metallurgically prepared to investigate the feasibility of floating intermetallic compounds with the consideration of Ce concentrations in the liquid Bi alloy and cooling rates. Cyclic voltammetry (CV) of CeCl3 in LiCl-KCl was conducted to examine the electrochemical behavior of Ce ion on liquid Bi pool electrode at 500 °C. The Bi-Ce alloy formed by the galvanostatic electrolysis of LiCl-KCl-CeCl3 on Bi cathode at 500 °C. The applied cathodic current was determined to be 20 mA/cm2 based on the CV results. The spatial distribution of intermetallic compounds was obtained by scanning electron microscope images which focused on the vertically entire cross sections of all Bi-Ce alloys. The intermetallic phase was characterized by both energy dispersive spectroscopy and X-ray diffractometry. From the experimental results, we suggest the feasibility of the density-based separation process and its flowsheet for the application to pyroprocessing technology.