Engineered carbon mineralization in ultramafic rocks for CO2 removal from air: Review and new insights

Kelemen, P. B.; McQueen, Noah; Wilcox, Jennifer; Renforth, Phil; Dipple, Gregory M.; Vankeuren, Amelia Paukert

doi:10.1016/j.chemgeo.2020.119628

Cited by 140 publications

(112 citation statements)

References 199 publications

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“…We see that increasing the feed gas CO 2 concentration from 410 ppm to even 0.5% reduces the energy and water consumption by 80%, and raising it again to 5% causes a further halving (Figure 11c,d). These results confirm the suggestion of Keleman et al 38 that reaction times would be significantly reduced when utilizing air enriched to a few percent in carbon dioxide to sparge through reacting alkaline rock.…”

Section: Resultssupporting

confidence: 90%

Enhanced weathering to capture atmospheric carbon dioxide: Modeling of a trickle‐bed reactor

2021

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Enhanced weathering (EW) of alkaline minerals can potentially capture CO2 from the atmosphere at gigaton scale, but the reactor design presents great challenges. We model EW with fresh water in a counter‐current trickle flow packed bed batch of 1–10 mm calcite particles. Weathering kinetics are integrated with the mass transfer of CO2 incorporating transfer enhancement by chemical reaction. To avoid flooding, flow rates must be reduced as the particles shrink due to EW. The capture rate is mainly limited by slow transfer of CO2 from gas to liquid although slow dissolution of calcite can also play a role in certain circumstances. A bed height of at least 7–8 m is required to provide sufficient residence time. The results highlight the need to improve capture rate and reduce energy and water consumption, possibly through enriching the feed with CO2 and further chemical acceleration of the mass transfer.

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Section: Resultssupporting

confidence: 90%

Enhanced weathering to capture atmospheric carbon dioxide: Modeling of a trickle‐bed reactor

2021

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“…5, and dissolution time trajectories calculated using a shrinking grain model (following Kelemen et al, 2020) for 1 t of mineral of a uniform grainsize (50, 100 and 500 µm) using W r for near-neutral pH conditions (log W Fo r = −9.3; W En r = −11; W An r = −12, after Bandstra et al, 2008). Finer grains dissolve more quickly and alkalinity production would increase by approximately one order of magnitude if a more realistic grainsize distribution is used (as shown in Kelemen et al, 2020). Only relatively fine-grained olivine (100 µm or less) weathers completely on decadal time scales (<50 years).…”

Section: Efficacy Of Enhanced Weathering Of Mine Wastesmentioning

confidence: 99%

“…Enhanced weathering is a CDR strategy based on accelerating rock dissolution that sequesters CO 2 through alkalinity production (Lackner et al, 1995;Hartmann et al, 2013;Renforth and Henderson, 2017;Alcalde et al, 2018;Andrews and Taylor, 2019;Li et al, 2019;Renforth, 2019;Beerling et al, 2020;Kelemen et al, 2020). The essence of the strategy is to mimic and accelerate natural chemical weathering, whereby minerals dissolve and react with atmospheric CO 2 and water (H2CO3 carbonic acid; reaction 1) to form bicarbonate solutions stabilised by solubilised cations (e.g., Ca2+, Mg2+; reactions 2 and 3).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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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.

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“…The most abundant mineral in all samples was anorthite, an aluminosilicate in the plagioclase feldspar mineral group. Although this mineral group is not typically viewed as ideal for carbon mineralization due to its low reactivity [34,35], its high abundance (comprising 39% of Earth's crust [36]) might still present volumes large enough for climate relevance.…”

Section: Silicate Groupmentioning

confidence: 99%

Carbon Mineralization with North American PGM Mine Tailings—Characterization and Reactivity Analysis

Woodall

Dipple

et al. 2021

Minerals

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Global efforts to combat climate change call for methods to capture and store CO2. Meanwhile, the global transition away from fossil energy will result in increased production of tailings (i.e., wastes) from the mining of nickel and platinum group metals (PGMs). Through carbon mineralization, CO2 can be permanently stored in calcium- and magnesium-bearing mine tailings. The Stillwater mine in Nye, Montana produces copper, nickel, and PGMs, along with 1 Mt of tailings each year. Stillwater tailings samples have been characterized, revealing that they contain a variety of mineral phases, most notably Ca-bearing plagioclase feldspar. Increases in inorganic carbon in the tailings and ion concentration in the tailings storage facilities suggest carbonation has taken place at ambient conditions over time within the tailings storage facilities. Two experiments were performed to simulate carbon mineralization at ambient temperature and pressure with elevated CO2 concentration (10% with N2), revealing that less than 1% of the silicate-bound calcium within the tailings is labile, or easily released from silicate structures at low-cost ambient conditions. The Stillwater tailings could be useful for developing strategies of waste management as production of nickel and PGM minerals increases during the global transition away from fossil energy, but further work is needed to develop a process that can realize their full carbon storage potential.

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Engineered carbon mineralization in ultramafic rocks for CO2 removal from air: Review and new insights

Cited by 140 publications

References 199 publications

Enhanced weathering to capture atmospheric carbon dioxide: Modeling of a trickle‐bed reactor

Enhanced weathering to capture atmospheric carbon dioxide: Modeling of a trickle‐bed reactor

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

Carbon Mineralization with North American PGM Mine Tailings—Characterization and Reactivity Analysis

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