Abstract
Due to the increasing demands and supply shortages for rare earth elements (REEs), the recovery of REEs from discarded NdFeB with high REE content has become extremely important. In this paper, a hydrometallurgical coupling process involving mechanical activation and selective acid leaching was proposed for the recovery of REEs from discarded NdFeB magnets. The effects of ball milling activation speed, hydrochloric acid concentration, and solid–liquid ratio on the leaching efficiencies of REEs in NdFeB magnets were studied. The results indicated that the ball milling activation method could enhance the reactivity of the samples through the action of mechanical force, which promoted the leaching efficiency and leaching speed of REEs. Under the optimum conditions (650-rpm activation speed, 0.4 M hydrochloric acid, 100 g/L solid–liquid ratio), the leaching efficiency of REEs increased up to 99% with low hydrochloric acid consumption and the leaching speed of REEs was triple than that of without activation. The final purity of recovered rare earth oxides reached up to 99.9%. All results demonstrated that ball milling activation coupled with selective leaching of hydrochloric acid could be an effective and environment-friendly strategy to achieve the recovery of REEs.
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Funding
This study was financially supported by the National Key Research and Development Project (2019YFC1906900) and the Guangdong Science and Technology Project (2020B121201003 and 2017A020216013).
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Fulin Mao: conceptualization, methodology, writing—original draft, investigation, writing—review & editing. Nengwu Zhu: conceptualization, supervision, validation. Wen Zhu: data curation, resources. Bowen Liu: writing—review & editing. Pingxiao Wu: writing—review & editing. Zhi Dang: writing—review & editing.
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Mao, F., Zhu, N., Zhu, W. et al. Efficient recovery of rare earth elements from discarded NdFeB magnets by mechanical activation coupled with acid leaching. Environ Sci Pollut Res 29, 25532–25543 (2022). https://doi.org/10.1007/s11356-021-17761-3
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DOI: https://doi.org/10.1007/s11356-021-17761-3