Reactive transport modelling of porewater geochemistry and sulfur isotope fractionation in organic carbon amended mine tailings

Craig, Andrew T.; Shkarupin, Alexi; Amos, Richard T.; Lindsay, Matthew B.J.; Blowes, David W.; Ptacek, Carol J.

doi:10.1016/j.apgeochem.2021.104904

Cited by 5 publications

(1 citation statement)

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“…Numerous studies have investigated the addition of organics including compost, biosolids, and organic-rich sludge to tailings for the purpose of mine reclamation, technosol formation, phytostabilization, and rehabilitation. − The addition of organics to mine tailings has also been shown to induce biogeochemical processes such as sulfate reduction, which can immobilize elements of concern (e.g., As) through the precipitation of sulfide minerals . In this study, coupling organic and inorganic carbon cycling dramatically accelerated brucite carbonation, which is often limited by CO 2 supply.…”

Section: Resultsmentioning

confidence: 89%

Carbonation, Cementation, and Stabilization of Ultramafic Mine Tailings

Power

Paulo

Long

et al. 2021

Environ. Sci. Technol.

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Tailings dam failures can cause devastation to the environment, loss of human life, and require expensive remediation. A promising approach for de-risking brucite-bearing ultramafic tailings is in situ cementation via carbon dioxide (CO 2 ) mineralization, which also sequesters this greenhouse gas within carbonate minerals. In cylindrical test experiments, brucite [Mg(OH) 2 ] carbonation was accelerated by coupling organic and inorganic carbon cycling. Waste organics generated CO 2 concentrations similar to that of flue gas (up to 19%). The abundance of brucite (2−10 wt %) had the greatest influence on tailings cementation as evidenced by the increase in total inorganic carbon (TIC; +0.17−0.84%). Brucite consumption ranged from 64−84% of its initial abundance and was mainly influenced by water availability. Higher moisture contents (e.g., 80% saturation) and finer grain sizes (e.g., clay-silt) that allowed for a better distribution of water resulted in greater brucite carbonation. Furthermore, pore clogging and surface passivation by Mg-carbonates may have slowed brucite carbonation over the 10 weeks. Unconfined compressive strengths ranged from 0.4−6.9 MPa and would be sufficient in most scenarios to adequately stabilize tailings. Our study demonstrates the potential for stabilizing brucite-bearing mine tailings through in situ cementation while sequestering CO 2 .

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