Abstract
Ultramafic and mafic mine tailings are a valuable feedstock for carbon mineralization that should be used to offset carbon emissions generated by the mining industry. Although passive carbonation is occurring at the abandoned Clinton Creek asbestos mine, and the active Diavik diamond and Mount Keith nickel mines, there remains untapped potential for sequestering CO2 within these mine wastes. There is the potential to accelerate carbonation to create economically viable, large-scale CO2 fixation technologies that can operate at near-surface temperature and atmospheric pressure. We review several relevant acceleration strategies including: bioleaching of magnesium silicates; increasing the supply of CO2 via heterotrophic oxidation of waste organics; and biologically induced carbonate precipitation, as well as enhancing passive carbonation through tailings management practices and use of CO2 point sources. Scenarios for pilot scale projects are proposed with the aim of moving towards carbon-neutral mines. A financial incentive is necessary to encourage the development of these strategies. We recommend the use of a dynamic real options pricing approach, instead of traditional discounted cash-flow approaches, because it reflects the inherent value in managerial flexibility to adapt and capitalize on favorable future opportunities in the highly volatile carbon market.
Highlights
Mines that generate ultramafic and mafic mine wastes have the capacity to more than offset their greenhouse gas (GHG) emissions by sequestering carbon dioxide (CO2) via carbon mineralization to create an environmental benefit while utilizing a waste product
Carbonation of ultramafic mine wastes could be accelerated by implementing strategies that enhance mineral dissolution, increase CO2 supply, and facilitate carbonate precipitation at near-surface conditions using Tailings storage facilities (TSFs) design strategies that promote carbonation
Passive carbonation under normal mining conditions is limited by the supply of CO2 [11,16]; conditions could arise in an acceleration scenario in which mineral dissolution or carbonate precipitation become rate limiting
Summary
Mines that generate ultramafic and mafic mine wastes (e.g., tailings) have the capacity to more than offset their greenhouse gas (GHG) emissions by sequestering carbon dioxide (CO2) via carbon mineralization to create an environmental benefit while utilizing a waste product. Mg-silicates; increasing the supply of CO2 via heterotrophic oxidation of waste organics, altering tailings management practices, and use of point sources with elevated CO2 partial pressures (pCO2); and biologically induced carbonate precipitation. These strategies have proven effective in laboratory-scale studies (e.g., [13,15,19,28,32,33]), pilot projects are crucially needed to evaluate strategies for accelerating carbon mineralization, which if successful and cost effective could be incorporated into TSF design with the purpose of sequestering CO2. We provide estimates of the operational costs of the proposed scenarios on a dollar per tonne of CO2 basis and recommend the use of a real options valuation model (comparable to what one might use to price a biotechnology start-up) to better assess the potential of carbon mineralization strategies
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