Vacuum distillation of a mixture of LiCl–KCl eutectic salts and RE oxidative precipitates and a dechlorination and oxidation of RE oxychlorides

Abstract

In this study, a vacuum distillation of a mixture of LiCl–KCl eutectic salt and rare-earth oxidative precipitates was performed to separate a pure LiCl–KCl eutectic salt from the mixture. Also, a dechlorination and oxidation of the rare-earth oxychlorides was carried out to stabilize a final waste form. The mixture was distilled under a range of 710–759.5 Torr of a reduced pressure at a fixed heating rate of 4 °C/min and the LiCl–KCl eutectic salt was completely separated from the mixture. The required time for the salt distillation and the starting temperature for the salt vaporization were lowered with a reduction in the pressure. Dechlorination and oxidation of the rare-earth oxychlorides was completed at a temperature below 1300 °C and this was dependent on the partial pressure of O 2. The rare-earth oxychlorides (NdOCl/PrOCl) were transformed to oxides (Nd 2O 3/PrO 2) during the dechlorination and oxidation process. These results will be utilized to design a concept for a process for recycling the waste salt from an electrorefining process.