Adsorption of rare earth elements in regolith-hosted clay deposits

DOI: 10.1038/s41467-020-17801-5

Authors: Anouk M. Borst (University of St. Andrews) , Martin P. Smith (University of Brighton) , Adrian Finch (University of St. Andrews) , Guillaume Estrade (GET, CNRS, IRD, UPS, University of Toulouse) , Cristina Villanova-de-benavent (University of Brighton) , Peter Nason (University of Brighton) , Eva Marquis (University of Brighton) , Nicola J. Horsburgh (University of St. Andrews) , Kathryn M. Goodenough (British Geological Survey) , Cheng Xu (Guilin University of Technology) , Jindřich Kynický (Mendel University; BIC Brno Spol. s.r.o.) , Kalotina Geraki (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 11

State: Published (Approved)
Published: December 2020
Diamond Proposal Number(s): 14793 , 15903

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.

Journal Keywords: Energy supply and demand; Environmental sciences; Geochemistry; Geology; Mineralogy

Subject Areas: Earth Science


Instruments: I18-Microfocus Spectroscopy

Documents:
s41467-020-17801-5.pdf