Global Carbon Dioxide Removal Potential of Waste Materials From Metal and Diamond Mining

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.