Global Carbon Dioxide Removal Potential of Waste Materials From Metal and Diamond Mining
Liam A. Bullock, Rachael H. James, Juerg Matter, Phil Renforth, D.A.H. Teagle
Abstract
There is growing urgency for CO 2 removal strategies to slow the increase of, and potentially lower, atmospheric CO 2 concentrations. Enhanced weathering, whereby the natural reactions between CO 2 and silicate minerals that produce dissolved bicarbonate ions are accelerated, has the potential to remove substantial CO 2 on decadal to centennial timescales. The global mining industry produces huge volumes of fine wastes that could be utilised as feedstock for enhanced weathering. We have compiled a global database of the enhanced weathering potential of mined metal and diamond commodity tailings from silicate-hosted deposits. Our data indicate that all deposit types, notably mafic and ultramafic rock-hosted operations and high tonnage Cu-hosting deposits, have the potential to capture ~1.1–4.5 Gt CO 2 annually, between 31 and 125% of the industry's primary emissions. However, current knowledge suggests that dissolution rates of many minerals are relatively slow, such that only a fraction (~3–21%) of this potential may be realised on timescales of <50 years. Field trials in mine settings are urgently needed and, if this prediction is confirmed, then methodologies for accelerating weathering reactions will need to be developed.