Storage

Lead PI

• Greg Dipple, University of British Columbia

Project Investigators

• Ulrich Mayer, University of British Columbia
• Michael Hitch, University of British Columbia
• Gordon Southam, University of Western Ontario

Postdoctoral Fellows

• Ian Power, University of British Columbia
• Sergio Bea, University of British Columbia

Graduate Students

• Anna Harrison, University of British Columbia
• Jiajie Li, University of British Columbia
• Jenine McCutcheon, University of Western Ontario

Goal

Some mine waste has an inherent but untapped capacity to absorb and trap the greenhouse gas carbon dioxide. In mine waste rock and tailings that are rich in magnesium silicate minerals, carbon fixation capacity is much larger than total greenhouse gas production from mine operations. The carbon mineralization project will develop processes for capturing carbon dioxide in mine wastes and fixing the carbon within mineral precipitates for safe long-term storage.

Activities

The project will examine the chemical reactions by which carbon dioxide is trapped and fixed in mineral form through controlled laboratory experiments so that they can be accelerated for enhanced carbon dioxide uptake. The role of biologically mediated reactions in carbon fixation, and the potential for microbially mediated acceleration of carbon uptake will be examined experimentally. The experiments will also be used to calibrate a geochemical model for predicting rates of carbon mineralization at a wide range of reaction conditions and for subsurface reaction in existing mine waste accumulations.

Milestone 1

Experimental work has demonstrated that uptake of CO2 into solution is rate limiting for carbon mineralization in mine tailings. Gas streams ranging in composition from atmospheric (~04%) to 100% CO2 were sparged into alkaline slurries containing brucite, a tailings mineral. Brucite was completely replaced by the magnesium carbonate mineral, nesquehonite, within 75, 12 and 7 hours with 10%, 50% and 10% CO2 gas respectively. Experimental carbon mineralization rates were accelerated by a factor of up to 2200, and exceed that required to carbonate all the brucite produced annually at the Mount Keith Nickel Mine (MKM) in Western Australia.

Milestone 2

Major Canadian industrial emitters of CO2 were compared with bedrock occurrences and mine sites for mafic to ultramafic rocks to access proximities of sources and sinks. Results show there are significant opportunities for CO2 storage in ultramafic rock-hosted mines and bedrock occurrences outside of the sedimentary basis that are optimal for more conventional carbon capture and storage.

Figure 1 shows a comparison of the range of passive annual carbonation rates at Diavik Diamond Mine, Northwest Territories, Canada (Wilson et al 2011), Clinton Creek chrysotile mine, Yukon Territory, Canada (Wilson et al 2009), and the Mount Keith Nickel Mine (MKM), Western Australia (Wilson 2009) with annual greenhouse gas emissions at various mine sites, total sequestration capacity, and potential annual carbonation rates at MKM via accelerated brucite carbonation.