Separation of uranium from lanthanides (La, Sm) with sacrificial Li anode in LiCl-KCl eutectic salt

Abstract

In the electrorefining process, the existence of cyclic electrolysis will lead to a low current efficiency. In order to eliminate the cyclic electrolysis, we explored a sacrificial Li metal anode for separating uranium (U) and lanthanides in this work. Electrochemical technique as well as electronic absorption spectroscopy (EAS) were employed to study the U species during the separation process. After potentiostatic deposition separation, the recovery efficiency of U reached 99%, and the main products were Al3U and Al4U. At the same time, the successful separation of U and lanthanides was achieved, and the separation factors for La and Sm were SFU/La = 2251, SFU/Sm = 4662, respectively. The results of EAS showed that both U and Sm remained in the lower valence states U(III) and Sm(II) during the separation process, indicating that the cyclic electrolysis was suppressed. Finally, the use of Li anode to suppress cyclic electrolysis has achieved a current efficiency of 93%. It is of great significance to improve current efficiency in the pyrochemical processing of spent nuclear fuel by molten salt electrolysis.