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Chemical Stability Evaluation of Ceramic Materials for Liquid Cadmium Cathode

액체카드뮴음금용 세라믹 소재의 화학적 안정성 평가

  • Received : 2012.10.31
  • Accepted : 2012.11.27
  • Published : 2013.03.30

Abstract

LCC (Liquid cadmium cathode) is used for electrowinning in pyroprocessing to recover uranium and transuranic elements simultaneously. It is one of the core technologies in pyroprocessing with higher proliferation resistance than a wet reprocessing because LCC-cell does not separate TRU from uranium. The crucible which holds the LCC is technically important because it should be nonconducting material to prevent deposition of metallic elements on the crucible outer surface. The chemical stability is also crucial factor to choose crucible material due to the strong reactivities of TRU and possible incorporation of Li metal during the operation. In this study, the chemical stabilities of four kinds of representative ceramic materials such as $Al_2O_3$, MgO, $Yl_2O_3$ and BeO were thermodynamically and experimentally evaluated at $500^{\circ}C$ with simulated LCC. The contact angle of LCC on ceramic materials was measured as function of time to predict chemical reactivity. $All_2O_3$ showed poorest chemical stability and the pores in BeO contributed to a decreases in contact angle. MgO and $Y_2O_3$ have superior chemical stability among the materials.

경제적이고 우수한 핵확산저항성을 갖는 파이로공정의 핵심 단위공정인 전해제련 공정에서 U와 TRU를 동시에 회수하기 위해 환원전극으로써 LCC가 사용된다. 한가지 원소만을 회수하는 금속음극과는 달리 LCC는 전기화학적으로 U와 TRU의 선택적 분리가 어려워 핵확산저항성을 높이는 기술의 핵심이라고 할 수 있다. LCC를 담아놓는 LCC 도가니는 U나 TRU로만 전착되어야하기 때문에 도가니는 전기적으로 절연되어야 한다. LCC와의 안정성과 회수된 TRU 및 용융염과의 화학적 안전성은 물론 공정 중 전착될 수 있는 금속 Li과의 반응성도 고려되어야하므로 LCC 도가니의 소재 특성은 매우 중요하다. 본 연구에서는 $Al_2O_3$, MgO, $Y_2O_3$, BeO 네 가지 대체 세라믹 소재의 화학적 안정성을 $500^{\circ}C$에서 모의 LCC로 열역학적 및 실험적으로 평가하였다. 세라믹 기판 위의 LCC 접촉각은 화학적 반응성을 예측하기 위해 시간에 따라 측정하였다. $Al_2O_3$는 가장 낮은 화학적 안정성 갖고 BeO는 재료 내에 존재하는 기공은 접촉각감소에 영향을 주었다. MgO, $Y_2O_3$는 우수한 화학적 안정성을 나타내었다.

Keywords

References

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