Adsorption of rare earth elements in regolith-hosted clay deposits

Anouk Margaretha Borst, Martin P. Smith, Adrian A. Finch, Guillaume Estrade, Cristina Villanova-de-Benavent, Peter Nason, Eva Marquis, Nicola J. Horsburgh, Kathryn M. Goodenough, Cheng Xu, Jindřich Kynický, Kalotina Geraki

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Abstract

Global resources of heavy Rare Earth Elements (REE) are dominantly sourced from Chinese regolith-hosted ion-adsorption deposits in which the REE are inferred to be weakly adsorbed onto clay minerals. Similar deposits elsewhere might provide alternative supply for these high-tech metals, but the adsorption mechanisms remain unclear and the adsorbed state of REE to clays has never been demonstrated in situ. This study compares the mineralogy and speciation of REE in economic weathering profiles from China to prospective regoliths developed on peralkaline rocks from Madagascar. We use synchrotron X-ray absorption spectroscopy to study the distribution and local bonding environment of Y and Nd, as proxies for heavy and light REE, in the deposits. Our results show that REE are truly adsorbed as easily leachable 8- to 9-coordinated outer-sphere hydrated complexes, dominantly onto kaolinite. Hence, at the atomic level, the Malagasy clays are genuine mineralogical analogues to those currently exploited in China.
Original languageEnglish
Article number4386
Number of pages15
JournalNature Communications
Volume11
DOIs
Publication statusPublished - 1 Sept 2020

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  • Coordination State of Metals in Mineral Systems

    Borst, A. M. (Creator), Finch, A. A. (Creator), Friis, H. (Creator), Horsburgh, N. (Creator), Gamaletsos, P. (Creator), Goettlicher, J. (Creator), Steininger, R. (Creator), Geraki, K. (Creator), Smith, M. P. (Creator), Estrade, G. (Creator), Villanova-de-Benavent, C. (Creator), Nason, P. (Creator), Marquis, E. (Creator), Goodenough, K. M. (Creator), Xu, C. (Creator) & Kynicky, J. (Creator), University of St Andrews, 10 Aug 2020

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