Mineral-water interactions in CO2 sequestration and mining environments

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Carbon management and sequestration are emerging areas in geoscience research that are motivated by concerns over the impacts of climate change, and the increasing financial incentives of carbon pricing. Contemporaneous to the need to reduce greenhouse gas (GHG) emissions, the generation of mine wastes, such as tailings (fine-grained waste rock), is escalating due to the increasing demand for resources. Consequently, the mining industry must develop more secure and cost-effective tailings management practices while improving environmental performance. The long-term goal of the proposed research is to understand fundamental geochemical, mineralogical, and geobiological processes at Earth's surface conditions and apply this knowledge to address environmental challenges. This research comprises three themes: (1) CO2 sequestration in mine wastes, (2) natural analogues for CO2 sequestration, and (3) tailings weathering and cementation. Weathering of mine tailings can result in the formation of carbonate minerals that store CO2, a key GHG. Through this process, certain mines have the capacity to more than offset the GHG emissions of mining, yet technologies need to be developed to take advantage of this capacity (Theme 1). Fieldwork conducted at mines in Canada, South Africa, and Botswana will determine CO2 sequestration capacities, while laboratory experiments will determine the extent and rates of CO2 sequestration within mine tailings. Study of natural weathering of rock with similar composition to the mine tailings will provide insights regarding the drivers and limitations of chemical weathering at Earth's surface that regulates atmospheric CO2 concentrations over geologic time (Theme 2). Lastly, beneficial weathering processes in tailings will be studied in the laboratory (Theme 3). These processes include cementation and surface passivation through mineral precipitation that can help limit metal release and improve tailings stability. The proposed research will advance our understanding of carbon cycling, weathering, and mine waste management while training a new generation of scientists to tackle pressing environmental issues. Students will acquire the knowledge and skills to launch their professional careers and become leaders in their chosen field. This research will make major contributions to the sustainable development of mineral resources and devise novel processes for CO2 sequestration to facilitate society's transition to a low-carbon economy. Research outcomes will help guide mining companies to utilize their mineral wastes to reduce GHG emissions, limit the costs of carbon pricing, improve tailings management, and benefit their social license to operate. Developing and implementing new technologies for reducing GHG emissions will create employment opportunities for Canadians in the emerging sectors of carbon management and sequestration.