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TitleCharacterization of Uranium and Rare Earth Element mobility downstream of a tailings impoundment near Bancroft, Ontario
AuthorLaidlow, A; Parsons, M; Jamieson, H
SourceProceedings of the 10th International Conference on Acid Rock Drainage (ICARD) and International Mine Water Association (IMWA) Conference; 2015 p. 1-10
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140272
Meeting10th International Conference on Acid Rock Drainage (ICARD) and International Mine Water Association (IMWA), 2015 Conference; Santiago; CL; April 21-24, 2015
Mediaon-line; digital
File formatpdf
Lat/Long WENS -78.0000 -77.5000 45.2500 45.0000
Subjectsenvironmental geology; geochemistry; Archean; greenstone belts; tailings; tailings geochemistry; tailings analyses; uranium; rare earths; rare earths geochemistry; heavy metals contamination; pollutants; x-ray diffraction; x-ray diffraction analyses; petrography; Bicroft Mine
Illustrationslocation maps; plots; pie charts
ProgramEnvironmental Geoscience, Tools for environmental impacts and adaptation for metal mining
AbstractAttenuation of uranium (U) and rare earth elements (REEs) has been observed in stream and wetland sediments, but the geochemical and mineralogical processes involved in sequestering these elements in natural systems are not fully understood. The decommissioned Bicroft Uranium Mine near Bancroft, ON, operated from 1957 to 1963, and processed approximately 2,284,421 tonnes of low-grade, disseminated U ore hosted by pegmatite dykes in amphibolite gneiss. During operations, the mine used two tailings impoundments and a modified stream and wetland system to reduce the concentrations of U, other metals, and radionuclides in tailings effluent to levels below the Provincial Water Quality Objectives. Since mine closure, the streams and wetland have continued to operate as a passive treatment system for tailings effluent, demonstrating the potential viability and longevity of natural attenuation to sequester U and REEs. In this study, we used tangential flow filtration, ICP-ES/MS, scanning electron microscopy, and synchrotron techniques (bulk- and micro-XANES, -XRF, and -XRD) to characterize processes controlling U and REE mobility and attenuation in tailings, sediment, and colloid samples. Results of this study indicate that Fe- and Mn-(oxyhydr)oxides, including goethite [?-FeO(OH)] and birnessite (?-MnO2), are the main mineral hosts for U and REEs in colloids and sediments. In addition, detrital grains of U- and REE-bearing minerals were found >200 m downstream in colloids and sediments, showing the potential for long-range transport of colloids and fine particulates in the stream system. While natural attenuation exhibits great potential to reduce U- and REE- concentrations, seasonal influences on the stability of trace metals in sediments were observed and may demonstrate the limitations of streams and wetlands as a viable method of attenuation. The results of this study are intended to aid development of more effective passive treatment systems and improve environmental monitoring strategies for U and REEs.
Summary(Plain Language Summary, not published)
The release of uranium (U) and rare earth elements (REEs) from mining wastes into surface waters is of concern for water quality, and the health of humans, organisms, and the surrounding environment. This study uses novel surface water filtration methods and cutting-edge mineralogical analyses to characterize the key processes that control the release, transport and fate of U and REEs from tailings at an abandoned U mine near Bancroft, Ontario. The results of this research will help to develop more effective water treatment systems and better environmental monitoring strategies for future U and REE developments.