Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
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Heat Balance during the Electrowinning of Neodymium Metal in Molten Salt

네오디뮴 금속의 전해 채취 중의 열수지

  • Cho, Sung-Wook (Resources Utilization Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Yu, Jeong-Hyun (Resources Utilization Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Choi, Ho-Gil (Department of Materials Science and Engineering, Seoul National University)
  • 조성욱 (한국지질자원연구원 자원활용연구본부) ;
  • 유정현 (한국지질자원연구원 자원활용연구본부) ;
  • 최호길 (서울대학교 재료공학부)
  • Received : 2022.05.15
  • Accepted : 2022.06.24
  • Published : 2022.06.30
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Abstract

Energy consumption per unit weight of metal (kwh/kg of metal) is one of the most important economic indicators in the process of molten salt electrolysis. It is related to the heat loss of salt bath and the current efficiency of the process. The current efficiency is highly dependent on electrolysis temperature. On the other hand, the temperature of salt bath may increase significantly due to the difference (larger energy input than consumption) in heat balance at the beginning of electrolysis, which may cause different electrolysis temperature from an initially targeted value. This results in a bad effect on current efficiency. Therefore, it will be helpful to the reduction of energy consumption to compare the calculated and measured values of the temperature change of salt bath through the heat balance review at the early stage of electrolysis and to evaluate the energy loss to outside. In this study, based on the authors' experimental data, the heat balance was reviewed at the beginning of the electrolysis, and it was possible to evaluate the energy loss to the outside and the increase of the temperature of the salt bath quantitatively. Through such a method, heat loss reduction plan can be derived and current efficiency can be improved so that energy consumption can be reduced.

용융염 전해 채취 공정에서 가장 중요한 경제 지표 중 하나는 에너지 원단위(kwh/kg of metal)이다. 이는 외부로 손실되는 에너지와 전류 효율에 관련된다. 전류 효율은 전해온도에 의해 크게 좌우된다. 한편 염욕의 온도는 전해 초기에 염욕의 열수지 차이로 인해 급격히 상승하여 처음에 목표했던 전해온도와 상이해질 수 있다. 염욕의 의도치 않은 온도 변화는 전류 효율에 악 영향을 미친다. 따라서 전해 초기를 대상으로 열수지 검토를 통해 염욕의 온도 변화에 대한 계산치와 실측치를 비교해 보고 외부로 손실되는 에너지를 평가하는 것은 에너지 원단위를 줄이는 데 도움이 될 것이다. 본 논문에서는 저자들의 실험 데이터를 이용하여 용융염 전해 채취 중의 열수지에 대해 검토하였으며 이를 통해 외부로의 열 손실과 염욕의 온도 상승을 정량적으로 평가할 수 있었다. 이와 같은 방법을 통하면 열 손실을 줄일 수 있는 방안을 도출하고 전해온도를 제어하여 전류 효율을 제고시킴으로써 에너지 원단위를 줄일 수 있다.

Keywords

Acknowledgement

본 연구는 국가과학기술연구회에 의해 지원된 창조형 융합연구사업 "국내산 함희토류광으로부터 희토류소재 제조기술 개발"의 일환으로 수행되었습니다.

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