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Quantifying the mineral carbonation potential of mine waste material : a new parameter for geospatial estimation Jacobs, Anthony David

Abstract

Direct aqueous mineral carbonation is a CO₂ sequestration method that can trap anthropogenic carbon dioxide as a thermodynamically stable carbonate. Ultramafic rocks considered waste at mining operations are targeted as the substrate source for carbonation in this research. Using mining waste to permanently fix CO₂ is a motivating factor for promoting industrial mineral carbonation as a viable carbon sequestration option. Experimental direct aqueous mineral carbonation was carried out on proposed Turnagain waste rock, a low-grade, high tonnage nickel sulphide deposit in northern British Columbia. 45 % magnesium silicate to magnesium carbonate conversion was achieved in two hours. The successful sequestration of CO₂ using mining waste rock and the opportunity of shared mining and mineral processing costs of a dual mining/mineral carbonation operation can aid in reducing economic and energy requirements, identified as key inhibiting factors of industrial mineral carbonation. The heterogenous mineralogy of ultramafic deposits commonly hosting mining operations makes quantifying the mineral carbonation potential (MCP) of the waste rock challenging. The MCP calculator, a novel Microsoft Excel™ spreadsheet program was developed to estimate the modal mineral abundance of ultramafic rocks for use in MCP estimation. The calculator is intended for use by the mining industry utilising abundant lithogeochemical data as a cost-effective tool in evaluating their deposit as a supplier of substrate material for industrial mineral carbonation operation. The calculator can be tailored to estimate MCP values based on a site specific mineral assemblage. MCP values generated represent composited sample length intervals along exploration drill holes. Estimation techniques traditionally used by the mining industry for resource estimation were evaluated as methods of geospatially interpolating MCP values. Both inverse distance and ordinary kriging were successful in interpolating MCP values. A capacity of 75 million tonnes of CO₂ within the proposed 28 year surface mine design at Turnagain was calculated. This capacity is significantly lower than the theoretical maximum capacity of 538 million tonnes calculated assuming all MgO within the waste rock is capable of sequestering CO₂ as magnesite (MgCO₃). The research highlights the importance of understanding and quantifying the mineralogy of ultramafic deposits when estimating their potential for mineral carbonation.

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Attribution-NonCommercial-NoDerivs 2.5 Canada