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

• Published in: Journal of hazardous materials 2008-12, Vol.160 (2), p.634-637
• Main Authors: Eun, Hee Chul, Yang, Hee Chul, Cho, Yung Zun, Lee, Han Soo, Kim, In Tae
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Dechlorination; Distillation; Electrorefining process; Exact sciences and technology; Hypochlorous Acid - chemistry; Lithium Chloride - analysis; Metals, Rare Earth - chemistry; Oxidation; Oxidation-Reduction; Pollution; Potassium Chloride - analysis; Rare-earth oxidative precipitates; Reactors; Temperature; Vacuum distillation; X-Ray Diffraction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2008.03.079

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.