Work

Organic-inorganic carbon cycling: Implications for CO2 mineralization of brucite-bearing mine tailings

Year: 2026

Type: article

Abstract: Enhanced weathering and mineralization of ultramafic tailings permanently stores carbon dioxide (CO2) within stable carbonate minerals. Brucite [Mg(OH)2], a minor phase (up to ~13 wt.%) of ultramafic tailings, offers substantial potential for CO2 sequestration, yet its carbonation is limited by CO2 supply. Here, we propose coupling organic and inorganic carbon cycling to accelerate brucite carbonation by amending ultramafic tailings with waste organics, a strategy often employed for remediation. This study aimed to understand the influence of tailings grain size and organics content on brucite carbonation and tailings cementation. Column experiments (~20 cm height, 10 weeks) involved layering waste organics and brucite-bearing tailings (2 wt.%) of different grain sizes (<63, 63–125, and 125–250 μm) and were compared to controls of organics and tailings only. Average carbonation rates for amended columns (102 kg CO2/t tailings/yr) were ~8× faster than tailings controls (13 kg CO2/t tailings/yr) that were only exposed to laboratory CO2 concentrations. Reacted tailings had depleted 13C compositions (δ13C = −10.9‰ to −9.9‰ VPDB) relative to initial tailings (−6.4‰), indicating incorporation of respired CO2. Cylindrical tests using compacted mixtures of tailings and organic matter exhibited 16–63% brucite carbonation along with unconfined compressive strengths of 0.08–0.51 MPa, a co-benefit of brucite carbonation. Our study demonstrates that using waste organics significantly accelerates brucite carbonation, which has implications for the remediation of ultramafic tailings. While this approach results in CO2 avoidance rather than removal of atmospheric CO2, this passive system exploits an inexpensive CO2 source for rapid carbonation.

Source: International journal of greenhouse gas control

DOI: 10.1016/j.ijggc.2026.104591

Authors: Justin A. Lockhart, Ian M. Power, Kwon Rausis, Shaheen Akhtar, Robert Caldwell, David French

Institutions: Trent University, SGS (Canada)

Language: English

Topic: CO2 Sequestration and Geologic Interactions

Subfield: Environmental Engineering

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Climate action

Open Access status: hybrid

Estimated APC paid: $4,100