Extraction of thorium from LiCl–KCl molten salts by forming Al–Th alloys: a new pyrochemical method for the reprocessing of thorium-based spent fuels

Abstract

The co-reduction process of Th(IV) and Al(III) ions in the LiCl-KCl-AlCl3-ThO2 molten salts with different concentrations of AlCl3 was investigated at 800 K on the tungsten electrode. Cyclic voltammetry, square wave voltammetry and open-circuit chronopotentiometry techniques were used to study electrochemical behaviors of Al(III), Th(IV) and Al-Th alloy formation processes. The results showed that five kinds of Al-Th intermetallic compounds could be formed in the AlCl3 poor system, whereas only one kind of Al-Th compound formed in the AlCl3 rich system. Al-Th alloys were obtained by potentiostatic electrolysis on aluminum electrodes and by galvanostatic electrolysis on a tungsten electrode. All the Al-Th alloys were characterized by scanning electron microscopy ( SEM) with energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The XRD results showed that the Al-Th compound prepared in the AlCl3 rich system was