Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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A study on the Separation/recovery of Rare Earth Elements from Wast Permanent Magnet by a Fractional Crystallization Method and Sulfuric Acid Leaching

폐영구자석 황산침출과 분별결정법에 의한 희토류 분리·회수에 대한 연구

  • Kim, Dae-Weon (Advanced Materials and Processing Center, Institute for Advanced Engineering(IAE)) ;
  • Kim, Hee-Seon (Advanced Materials and Processing Center, Institute for Advanced Engineering(IAE)) ;
  • Kim, Boram (Advanced Materials and Processing Center, Institute for Advanced Engineering(IAE)) ;
  • Jin, Yun-Ho (Advanced Materials and Processing Center, Institute for Advanced Engineering(IAE))
  • 김대원 (고등기술연구원 신소재공정센터) ;
  • 김희선 (고등기술연구원 신소재공정센터) ;
  • 김보람 (고등기술연구원 신소재공정센터) ;
  • 진연호 (고등기술연구원 신소재공정센터)
  • Received : 2022.03.08
  • Accepted : 2022.04.01
  • Published : 2022.06.30
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Abstract

Nd-Fe-B waste permanent magnet contains about 20~30% rare earth elements and about 60~70% iron elements, and the rare earth and iron components were recovered through sulfuric acid leaching and fractional crystallization. Oxidation roasting was not performed for separation and recover of the rare earth and iron elements. The leaching characteristics were confirmed by using as variables the sulfuric acid concentration and the mineral solution concentration ratio. Sulfuric acid leaching was carried out for 3 hours for each sulfuric acid concentration. The leached solid phase was characterized for its crystalline phase, composition, and quantitative components by XRD and XRF analysis, and the filtrate was analyzed for components by ICP analysis. With sulfuric acid leaching at 3M sulfuric acid concentration, neodymium compounds were formed, the iron content was the least, and the recovery rate was high. After the filtrate remaining after sulfuric acid leaching was subjected to fractional crystallization through evaporation and concentration, the neodymium component was found to be concentrated 7.0 times and the iron component 2.8 times. In this study, the recovery rate of waste permanent magnets through sulfuric acid leaching and a fractional crystallization method without an oxidation and roasting process was confirmed to be about 99.4%.

Nd-Fe-B 폐영구자석 스크랩에는 희토류가 약 20~30% 함유되어 있고 철이 약 60~70% 함유되어 있으며, 황산침출 및 분별결정법을 통하여 희토류 및 철 성분을 회수하고자 하였다. 희토류와 철을 분리·회수하기 위하여 산화배소를 하지 않고 황산농도 및 광액농도비를 변수로 하여 침출특성을 확인하였다. 황산침출은 농도별로 3시간 동안 침출을 진행하였고 침출된 고상을 X-ray diffraction (XRD) 및 XRF (X-ray florescence spectrometry) 분석으로 결정상 및 조성 및 정량적 성분을 확인하였으며, 여액은 ICP 분석을 시행하였다. 3M 황산농도에서 침출했을 경우 네오디뮴 황산화물로 형성되었고 철 성분이 가장 적으며 회수율이 높았다. 남은 여액은 증발농축을 통하여 분별결정법을 하였으며 네오디뮴 성분은 7.0배 농축되었고 철 성분은 2.8배 농축되었다. 본 논문에서 폐영구자석의 산화배소 공정단계 없이 황산침출 및 분별결정법을 통한 희토류 성분의 회수율은 약 99.4%로 확인되었다.

Keywords

Acknowledgement

본 연구는 2021년도 산업통상자원부의 재원으로 한국산업기술평가관리원의 지원을 받아 수행한 연구 과제입니다(클린팩토리 기술개발사업 No. 20015769).

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