Advanced technology for the manufacture of moltn RE chloride salts

Young-Joon Shin, Ik-Soo Kim, Seung-Chul Oh, Won-Kyung Lee, Sun-Seok Hong

Korea Atomic Energy Research Institute, 150 Duckjin-dong, Yusong-gu, Taejon, Korea

Tel: +82-42-868-8229, Fax: +82-42-868-8370, E-mail: nyjshin@nanum.kaeri.re.kr

  The highly purified rare-earth(RE) elements and compounds used as the raw materials in electronic, optical, super-conductor and catalyst industries were conventionally manufactured by the wet technology such as leaching, solvent extraction , precipitation, ion chromatography, etc. However the application of molten salt technology to purify the rare-earth elements, which is called as the dry technology, seems to achieve competitiveness in economical and environmental aspects when compared with the conventionsal wet method. In the dry process that is composed of several unit processes, the chlorination process of RE oxides is one of the most important unit processes. RE chloride salts were usually obtained by the reaction of RE oxide and Cl2 saturated with CCl4.

  In the present study, the preliminary thermodynamic analysis to determine properly the range of the chlorination temperature for the chemical system of RE2O3, C, and Cl2 has been done. The experiments to determine the optimal chlorination condition have also been done over several conditions of reaction temperature and composition.

  The volatile and hygroscopic characteristics of RE chlorides result in the poor recovery yields of chlorination products if there is not any proper tool. In order to increase the recovery yield, the of-gas ventilation system in the chlorination process has been modified and its effect is discussed.