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A study on dehydration of rare earth chloride hydrate

염화 희토류 수화물의 탈수화에 관한 연구

  • Received : 2012.03.27
  • Accepted : 2012.05.02
  • Published : 2012.06.30

Abstract

The dehydration schemes of rare earth (La, Ce, Nd, Pr, Sm. Eu, Gd, Y) chloride hydrates was investigated by using a dehydration apparatus. To prevent the formation of the rare earth oxychlorides, the operation temperature was changed step by step ($80{\rightarrow}150{\rightarrow}230^{\circ}C$) based on the TGA (thermo-gravimetric analysis) results of the rare earth chloride hydrates. A vacuum pump and preheated Ar gas were used to effectively remove the evaporated moisture and maintain an inert condition in the dehydration apparatus. The dehydration temperature of the rare earth chloride hydrate was increased when the atomic number of the rare earth nuclide was increased. The content of the moisture in the rare earth chloride hydrate was decreased below 10% in the dehydration apparatus.

염화희토류 수화물($RECl_3{\cdot}xH_2O$) 내 존재하는 수분을 제거하기 위하여 탈수화 장치를 제작하여 8가지(La, Ce, Nd, Pr, Sm. Eu, Gd, Y)$Cl_3{\cdot}xH_2O$에 대한 탈수화 실험을 수행하였다. 탈수화 과정 중 희토류옥시염화물의 형성을 억제하기 위하여 TGA 분석을 바탕으로 하여 단계적인 온도 상승($80{\rightarrow}150{\rightarrow}230^{\circ}C$)구간을 설정하였으며 증발된 수분의 원활한 이동을 위하여 예열된 Ar 가스와 vacuum pump를 이용하였다. 각 온도구간에서의 탈수화 정도를 살펴본 결과 $YCl_3{\cdot}xH_2O$를 제외한 염화희토류 수화물은 원자번호가 높을수록 높은 온도에서 더 많은 탈수화가 일어남을 알 수 있었다. 탈수화 과정 후 희토류옥시염화물의 형성은 보이지 않았으며 염화 희토류 수화물 내 수분을 10%이하로 감소시킬 수 있었다.

Keywords

References

  1. Y. J. Cho, H. C. Yang, H. C. Eun, E. H. Kim, I. T. Kim, "Precipitation of rare earth chlorides in a LiCl-KCl eutectic molten salt", J. Korean Ind. Eng. Chem., 18(4), pp. 361-365 (2007).
  2. H. C. Eun, H. C. Yang, I. T. Kim, H. S. Lee, Y. J. Cho, "Recovery of residual LiCl-KCl eutetics salts in radioactive rare earth precipitates", J. of Korean Radioactive Waste Society, 8(4), pp. 303-309 (2010).
  3. H. C. Eun, H. C. Yang, Y. J. Cho, H. S. Lee, I. T. Kim, "Thermal behavior of PrCl3 in an oxidizing condition", J. of Korean Radioactive Waste Society, 7(4), pp. 207-212 (2009).
  4. J. Sundstrom, " Method for producing anhydrous rare earth chlorides", PCT. Pattent No. WO 97-07057, Feb. 1997.
  5. F. Picard, "Essentially anhydrous admixtures of dehydrated rare earth halides and alkali/alkaline earth metal halides", US. Pattent No. 5178664, Jan. 1993.
  6. J. Sundstrom, O. Wijk, "Investigation of the dehydration schemes of NdCl3.6H2O, TbCl3.$6H_{2}O$ and $DyCl_{3}$.$6H_{2}O$ using a fluidized bed", J. Alloys and compounds., 249, pp. 224-228(1997). https://doi.org/10.1016/S0925-8388(96)02537-6
  7. V. V. Hong, J. Sundstrom, "The dehydration schemes of rare-earth chlorides", Thermochimica Acta., 307, pp. 37-43(1997). https://doi.org/10.1016/S0040-6031(97)00296-7
  8. G. G. PAI, A. A. AUDI, R. V. NAIR, N. R. BHAGOJI, "Process for preraring anhydrous rare earth metal halides", PCT. Patent No. WO 2010/032256, March. 2010.
  9. A. Potapov, V. Khokhlov, Y. Sato, "Viscosity of molten rare earth metal trichlorides I. CeCl3, $NdCl_{3}$, $SmCl_{3}$, $DyCl_{3}$ and $ErCl_{3}$", A. Naturforsch, 58a, pp. 457-463 (2003).
  10. H. Chen, P. Yang, C. Zhou, C. Jiang, "Bridgman growth of LaCl3:Ce3+ crystal on non-vacuum atmosphere", J. Alloys and compounds., 449, pp.172-175 (2008). https://doi.org/10.1016/j.jallcom.2006.02.089
  11. J. Sundstrom, V. V. Hong, "Investigation of the Kinetics of the fluidized bed process for the dehydration of $NdCl_{3}$.$6H_{2}O$, $TbCl_{3}$.$6H_{2}O$ and $GyCl_{3}$.$6H_{2}O$", Thermochimica Acta., 306, pp. 13-21 (1997). https://doi.org/10.1016/S0040-6031(97)00293-1