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Molybdenum speciation in uranium mine tailings using X-ray absorption spectroscopy.
Joseph Essilfie-Dughan1, Ingrid J Pickering, M Jim Hendry
1Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada. joe377@mail.usask.ca
Environmental Science & Technology
|December 15, 2010
Summary
Molybdenum in uranium mine tailings exists as molybdate (+6 oxidation state). Its speciation, including NiMoO(4) and CaMoO(4) complexes, depends on the original ore
Area of Science:
- Environmental Science
- Geochemistry
- Nuclear Science
Background:
- Uranium mill tailings in Saskatchewan contain high molybdenum (Mo) concentrations.
- Long-term Mo mobilization from tailings to groundwater is an environmental concern.
Purpose of the Study:
- Characterize the long-term stability of Mo in tailings.
- Determine the chemical speciation of Mo in tailings samples from the Deilmann Tailings Management Facility (DTMF).
Main Methods:
- X-ray absorption spectroscopy (XAS) was employed to analyze Mo speciation.
- Mo K-edge XAS spectra were compared to reference compounds.
- Principal component analysis and linear combination fitting were used to identify Mo species.
Main Results:
- Mo in tailings is primarily in the molybdate (+6 oxidation state).
- Key Mo species identified include NiMoO(4), CaMoO(4), and molybdate adsorbed onto ferrihydrite.
- Mo speciation is influenced by Fe/Mo and Ni/Mo molar ratios, suggesting dependence on original ore chemistry.
Conclusions:
- The chemical speciation of Mo in uranium mine tailings is complex and influenced by mineralogy.
- Understanding Mo speciation is crucial for assessing the long-term environmental risks associated with uranium mill tailings.
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