25-27 November 2015
National Centre for Synchrotron Science
Australia/Melbourne timezone

Uranium speciation and mineralogy within an organic-rich ore deposit (Mulga Rock, WA); implications for U mobility and extraction

26 Nov 2015, 13:30
Exhibition space (National Centre for Synchrotron Science)

Exhibition space

National Centre for Synchrotron Science

Australian Synchrotron 800 Blackburn Road Clayton VIC 3168
Board: EM-17
Poster Energy Materials Poster Session 1


Susan Cumberland (Australian Synchrotron)


Uranium (U) is internationally important as a low carbon energy source, however, its extraction and radioactive waste legacies require continuing research into the factors controlling U mobility. Uranium mobility is strongly influenced by its oxidation state: U(VI) (e.g., U(VI)-carbonate) is more soluble than U(IV), which mineralises as coffinite [USiO4] or uraninite [UO2]. By identifying the U-species present in natural systems, insights can be gained into ore formation, U extractability (e.g. in-situ leaching) and contaminated site management. The influence of U by organic matter (OM) on both uranium mobility and fixation is interesting, as within deposits higher U concentrations often coincide with OM-rich zones. Alternatively, OM may also inhibit sorption of U via formation of soluble complexes. Analytical challenges include identifying U-species within OM-rich samples. Synchrotron radiation, in particular X-ray Absorption Spectroscopy (XAS) and X-ray fluorescence microscopy (XFM), have proven advantageous in studying oxidation state and coordination. Here, we present the results of XAS analyses of Mulga Rock cores, an OM-hosted U-deposit in WA. We show that within OM, uranium is finely dispersed displaying simple monomeric structures analogous to uranyl silicate, suggesting potential for U extractability. However, where uranium is locally concentrated, coffinite predominates. Results of XFM-XANES and XRD transects also document a redox gradient of U(IV) to U(VI) across a U-pyrite boundary.
Keywords Uranium, organic matter, mobility, XAS, XFM, Mulga Rock deposit

Primary author

Susan Cumberland (Australian Synchrotron)


Daryl Howard (Australian Synchrotron) Dr Grant Douglas (CSIRO, Land and Water, Wembley 6913, Perth, Western Australia) Dr John Moreau (School of Earth Sciences, University of Melbourne, Parkville 3010, Victoria) Dr Katy Evans (School of Applied Geology, Curtin University, Bentley 6845, Perth, Western Australia) Dr Louise Fisher (CSIRO, Mineral Resources, CSIRO, Bentley 6102, Perth, Western Australia) Dr Martin de Jonge (Australian Synchrotron) Dr Peter Kappen (Australian Synchrotron)

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