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A green and efficient technology to recover rare earth elements from weathering crusts

Nature Sustainability volume 6, pages 81–92 (2023)Cite this article

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Abstract

Heavy rare earth elements (HREEs) such as Gd–Lu, Sc and Y are irreplaceable metals for a number of critical (including clean) technologies, but they are scarce. Ion-adsorption deposits, which form within weathering crusts, supply more than 95% of the global HREE demand. However, these deposits are currently mined via ammonium-salt-based leaching techniques that are responsible for severe environmental damage and show low recovery efficiency. As a result, the adoption of such techniques is restricted for REE mining, further exacerbating REE scarcity, which in turn could lead to supply chain disruptions. Here we report the design of an innovative REE mining technique, electrokinetic mining (EKM), which enables green, efficient and selective recovery of REEs from weathering crusts. Its feasibility is demonstrated via bench-scale, scaled-up and on-site field experiments. Compared with conventional techniques, EKM achieves ~2.6 times higher recovery efficiency, an ~80% decrease in leaching agent usage and a ~70% reduction in metallic impurities in the obtained REEs. As an additional benefit, the results point to an autonomous purification mechanism for REE enrichment, wherein the separation process is based on the mobility and reactivity diversity between REEs and metallic impurities. Overall, the evidence presented suggests that EKM is a viable mining technique, revealing new paths for the sustainable harvesting of natural resources.

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Fig. 1: Illustration of IAD mining via EKM and AIP mechanisms.
Fig. 2: Setup for the bench-scale EKM experiments and the obtained results.
Fig. 3: Analysis of precipitates on the cathode plate after EKM treatment.
Fig. 4: Setup for the scaled-up EKM experiments and the obtained results.
Fig. 5: Setup for the on-site field EKM experiment and the obtained results.

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Data availability

All data generated for this study are available in the paper and the Supplementary Information.

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Acknowledgements

We thank J. Liu, Y. Zhu and Y. Xu in our group for their support in the field EKM experiments, discussions and suggestions. This work was supported by the Guangdong Major Project of Basic and Applied Basic Research (grant no. 2019B030302013 to H.H.), the National Key R&D Program of China (grant no. 2021YFC2901701 to H.H.), the National Natural Science Foundation of China (grant nos 41825003 to J.Z. and 42102037 to G.W.), the Guangdong Basic and Applied Basic Research Foundation (grant no. 2019A1515110720 to G.W.), the Guangdong Special Support Program (grant nos 2017TX04Z243 to R.Z. and 2019TX05L169 to J.Z.) and Science and Technology Planning of Guangdong Province, China (grant nos 2017B030314175 and 2020B1212060055). This is contribution no. IS-3245 from GIGCAS.

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Authors and Affiliations

  1. CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Material, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China

    Gaofeng Wang, Jie Xu, Lingyu Ran, Runliang Zhu, Xiaoliang Liang, Shichang Kang, Yuanyuan Wang, Jingming Wei, Lingya Ma, Jianxi Zhu & Hongping He

  2. CAS Center for Excellence in Deep Earth Science, Guangzhou, China

    Gaofeng Wang, Jie Xu, Lingyu Ran, Runliang Zhu, Xiaoliang Liang, Shichang Kang, Yuanyuan Wang, Jingming Wei, Lingya Ma, Jianxi Zhu & Hongping He

  3. University of Chinese Academy of Sciences, Beijing, China

    Gaofeng Wang, Jie Xu, Lingyu Ran, Runliang Zhu, Xiaoliang Liang, Shichang Kang, Yuanyuan Wang, Jingming Wei, Lingya Ma, Jianxi Zhu & Hongping He

  4. Institute of Mechanics, Chinese Academy of Sciences, Beijing, China

    Bowen Ling

  5. School of Civil Engineering, Wuhan University, Wuhan, China

    Yanfeng Zhuang

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Contributions

H.H. and J.Z. led the projects and designed the experiments. G.W. performed the experiments with assistance from J.X., L.R., S.K. and Y.W. H.H., G.W., J.Z., R.Z., X.L., J.W., L.M. and Y.Z. analysed the data. H.H., G.W., R.Z. and B.L. wrote the manuscript, which was revised by all authors.

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Correspondence to Hongping He.

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Nature Sustainability thanks Zongguo Wen and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Texts 1–5, Reactions 1–3, Discussion, Figs. 1–20, Tables 1–10 and References.

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Wang, G., Xu, J., Ran, L. et al. A green and efficient technology to recover rare earth elements from weathering crusts. Nat Sustain 6, 81–92 (2023). https://doi.org/10.1038/s41893-022-00989-3

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