Laboratory core investigations of sandstone-hosted uranium for in situ recovery

ABSTRACT

Several core plugs from a 1243 m-deep borehole penetrating the Westwater Canyon Member of the Morrison Formation in New Mexico (USA) have been investigated by various petrophysical methods to evaluate the potential of extracting deeply buried sandstone-hosted uranium deposits by in situ recovery (ISR). Petrophysics and mineralization patterns of the host rock in the target aquifer are crucial parameters for ISR amenability and were determined according to the ISR feasibility criteria. Mineralogical investigations revealed a secondary uranium mineralization mainly coating the silica grains of the arkosic sandstone and some interstitial pore fillings. The differences between mineralized and non-mineralized sandstone plugs are highlighted by nuclear magnetic resonance (NMR), X-ray microcomputed tomography, and spectral induced polarization (SIP). The NMR results show a doubling of the clay- and capillary-bound water and a decease of free-fluid porosity of mineralized samples. A correlation of mineralization grade and polarization is observed through the SIP investigations.

KEYWORDS:

• In situ recovery
• laboratory core analysis
• uranium
• petrophysics
• NMR
• SIP
• µCT
• leaching feasibility

Acknowledgements

The authors would like to thank Dr Raphael Dlugosch (LIAG Hannover) for his support with the NMR measurements. Dr Wolfgang Debschütz (TU Clausthal) for the support with the nitrogen adsorption method. Marcus Liebner (UIT Dresden) for his support with the laboratory experiments and Dr Horst Märten (UIT Dresden) for his guidance. Special thanks goes to the reviewers whose constructive contributions are much appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.