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

Abstract

There is growing urgency for CO2 removal strategies to slow the increase of, and potentially lower, atmospheric CO2 concentrations. Enhanced weathering, whereby the natural reactions between CO2 and silicate minerals that produce dissolved bicarbonate ions are accelerated, has the potential to remove substantial CO2 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 CO2 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.

Toward Sustainable Reprocessing and Valorization of Sulfidic Copper Tailings: Scenarios and Prospective Lca

“…Other breakthrough technologies beyond our analysis might penetrate the market and become commercialized, amplifying the GHG reduction potential through improved energy and resource intensity. For example, various types of tailings have been regarded as promising storage for the carbonation process, enabling CO 2 capture for emissions offset (Bullock et al, 2021;Wilson et al, 2014). Such solutions should also be assessed with LCA to complement the present study.…”

Carbonate Coprecipitation for Cd and Zn Treatment and Evaluation of Heavy Metal Stability Under Acidic Conditions

“…Despite these environmental concerns, some combustion, mining, and other alkaline industrial wastes can provide environmental benefits because of their cation content, − mainly in the form of Ca 2+ , Mg 2+ , and Fe 2+ , which can precipitate as carbonate minerals, thereby acting as a sink for CO 2 gas in the Earth′s atmosphere. For example, the global annual potentials for CO 2 capture were found to be 4.5 Gt for ultramafic mine tailings and 0.2 Gt for coal ash, suggesting that alkaline wastes may contribute significantly to achieving net negative emissions . A wealth of literature has quantified the kinetics of carbonation reactions, availability of waste materials, economic feasibility, and heat potentials − in the context of CO 2 sequestration efforts.…”

“…For example, the global annual potentials for CO 2 capture were found to be 4.5 Gt for ultramafic mine tailings and 0.2 Gt for coal ash, suggesting that alkaline wastes may contribute significantly to achieving net negative emissions . A wealth of literature has quantified the kinetics of carbonation reactions, availability of waste materials, economic feasibility, and heat potentials − in the context of CO 2 sequestration efforts. It remains to be seen whether engineered carbon mineralization processes can offer permanent and simultaneous sequestration of both CO 2 and heavy metals.…”

Quantification of CO2 removal in a large-scale enhanced weathering field trial on an oil palm plantation in Sabah, Malaysia

“…To date, the potential of enhanced weathering for removing atmospheric CO 2 has principally been estimated using modeling studies (e.g., Renforth, 2012;Taylor et al, 2016;Beerling et al, 2020;Bullock et al, 2021), or based on results from small-scale mesocosm or laboratory experiments (e.g., Renforth et al, 2015;Amann et al, 2020;Kelland et al, 2020;Pogge von Strandmann et al, 2021). Most mesocosm and laboratory studies to date have focused on amending soils with relatively fast weathering silicate minerals, notably olivine, or fast weathering silicate rocks, such as dunite that contains a high proportion of olivine.…”