Department of Engineering Science, Parks Road, University of Oxford, Oxford, United Kingdom.
Department of Engineering Science, Parks Road, University of Oxford, Oxford, United Kingdom.
Sci Total Environ. 2022 Feb 20;808:152111. doi: 10.1016/j.scitotenv.2021.152111. Epub 2021 Dec 4.
Chemically reactive mine tailings are a potential resource for drawing down carbon dioxide out of the atmosphere in mineral weathering schemes. Such carbon dioxide removal (CDR) systems, applied on a large scale, could help to meet internationally agreed targets for minimising climate change, but crucially we need to identify what materials could react fast enough to provide CDR at relevant climate change mitigation timescales. This study focuses on a range of silicate-dominated tailings, calculating their CDR potential from their chemical composition (specific capacity), estimated global production rates, and the speed of weathering under different reaction conditions. Tailings containing high abundances of olivine, serpentine and diopside show the highest CDR potential due to their favourable kinetics. We conclude that the most suitable tailings for CDR purposes are those associated with olivine dunites, diamond kimberlites, asbestos and talc serpentinites, Ni sulphides, and PGM layered mafic intrusions. We estimate the average annual global CDR potential of tailings weathered over the 70-year period 2030-2100 to be ~93 (unimproved conditions) to 465 (improved conditions) Mt/year. Results indicate that at least 30 countries possess tailings materials that, under improved conditions, may offer a route for CDR which is not currently utilised within the mining industry. By 2100, the total cumulative CDR could reach some 33 GtCO, of which more than 60% is contributed by PGM tailings produced in Southern Africa, Russia, and North America. The global CDR potential could be increased by utilization of historic tailings and implementing measures to further enhance chemical reaction rates. If practical considerations can be addressed and enhanced weathering rates can be achieved, then CDR from suitable tailings could contribute significantly to national offset goals and global targets. More research is needed to establish the potential and practicality of this technology, including measurements of the mineral weathering kinetics under various conditions.
化学反应性矿山尾矿是从大气中提取二氧化碳的潜在资源，在矿物风化方案中。这种碳去除（CDR）系统，如果大规模应用，可以帮助实现国际上减少气候变化的目标，但至关重要的是，我们需要确定哪些材料可以足够快地反应，以在相关的气候变化缓解时间内提供 CDR。本研究集中在一系列硅酸盐占主导地位的尾矿上，根据其化学成分（比容量）、估计的全球生产速度以及在不同反应条件下的风化速度来计算其 CDR 潜力。含有高丰度橄榄石、蛇纹石和透辉石的尾矿由于其有利的动力学特性显示出最高的 CDR 潜力。我们得出的结论是，最适合 CDR 目的的尾矿是那些与橄榄石橄榄岩、金刚石金伯利岩、石棉和滑石蛇纹岩、镍硫化物和 PGM 层状镁铁质侵入体有关的尾矿。我们估计，在 2030-2100 年的 70 年期间风化的尾矿的年平均全球 CDR 潜力约为 93（未改进条件）至 465（改进条件）Mt/年。结果表明，至少有 30 个国家拥有尾矿材料，在改进条件下，这些尾矿材料可能为采矿行业目前未利用的 CDR 提供途径。到 2100 年，总累计 CDR 可能达到 330 亿吨左右，其中超过 60%来自南非、俄罗斯和北美的 PGM 尾矿。如果能够解决实际问题并进一步提高化学反应速率，那么利用历史尾矿和实施措施来提高全球 CDR 潜力是可能的。如果能够解决实际问题并进一步提高化学反应速率，那么利用合适的尾矿进行 CDR 可能会对国家抵消目标和全球目标做出重大贡献。需要进行更多的研究来确定这项技术的潜力和实用性，包括在各种条件下测量矿物风化动力学。
