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<p>CO<sub>2</sub> mineralization in coal-based solid waste cemented backfill offers a promising solution for simultaneous solid waste utilization and long-term CO<sub>2</sub> sequestration. The migration and diffusion behavior of CO<sub>2</sub> within cemented backfill directly affect the efficiency of CO<sub>2</sub> mineralization and sequestration. The mineralization reaction between coal-based solid waste and CO<sub>2</sub> modifies the pore structure of cemented backfill, thereby affecting CO<sub>2</sub> migration and storage capacity. Therefore, elucidating the evolution of porosity in coal-based solid waste cemented backfill during CO<sub>2</sub> mineralization is of significant importance. In this study, X-ray computed tomography (CT) was employed to investigate the pore structure evolution of coal-based solid waste cemented backfill. A self-developed CO<sub>2</sub> mineralization curing system for coal-based solid waste cemented backfill was established. High-resolution CT scanning coupled with three-dimensional fracture reconstruction was used to systematically quantify the effects of curing time and gangue particle size gradation on pore structure evolution throughout the curing process, and the structural evolution of pore throats was further elucidated. The results indicate that the porosity of the backfill initially increased slightly from 0.82 to 0.87% and then gradually decreased to 0.71% with increasing curing time, accompanied by a continuous decrease in pore throat radius and an initial increase followed by a decrease in tortuosity and coordination number. As the gradation coefficient increased, the fractal dimension of the pore structure continuously increased, whereas the porosity decreased significantly from 0.82 to 0.68%, together with decreases in pore throat radius and coordination number and an increase in tortuosity. Furthermore, the interaction mechanism between CO<sub>2</sub> diffusion pathways and the deposition of mineralization products during the curing process was elucidated from a micro-to-mesoscale perspective. These findings provide a theoretical basis for optimizing the engineering design of CO<sub>2</sub> mineralization and sequestration in coal-based solid waste cemented backfill.</p>

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Pore Structure Evolution in CO2-Mineralized Coal-Based Solid Waste Cemented Backfill Based on X-Ray CT: Effects of Curing Time and Particle Size Gradation

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Hao Yan,
  • Rang Chen,
  • Jixiong Zhang,
  • Weihang Mao,
  • Haoran Wang,
  • Nan Zhou

摘要

CO2 mineralization in coal-based solid waste cemented backfill offers a promising solution for simultaneous solid waste utilization and long-term CO2 sequestration. The migration and diffusion behavior of CO2 within cemented backfill directly affect the efficiency of CO2 mineralization and sequestration. The mineralization reaction between coal-based solid waste and CO2 modifies the pore structure of cemented backfill, thereby affecting CO2 migration and storage capacity. Therefore, elucidating the evolution of porosity in coal-based solid waste cemented backfill during CO2 mineralization is of significant importance. In this study, X-ray computed tomography (CT) was employed to investigate the pore structure evolution of coal-based solid waste cemented backfill. A self-developed CO2 mineralization curing system for coal-based solid waste cemented backfill was established. High-resolution CT scanning coupled with three-dimensional fracture reconstruction was used to systematically quantify the effects of curing time and gangue particle size gradation on pore structure evolution throughout the curing process, and the structural evolution of pore throats was further elucidated. The results indicate that the porosity of the backfill initially increased slightly from 0.82 to 0.87% and then gradually decreased to 0.71% with increasing curing time, accompanied by a continuous decrease in pore throat radius and an initial increase followed by a decrease in tortuosity and coordination number. As the gradation coefficient increased, the fractal dimension of the pore structure continuously increased, whereas the porosity decreased significantly from 0.82 to 0.68%, together with decreases in pore throat radius and coordination number and an increase in tortuosity. Furthermore, the interaction mechanism between CO2 diffusion pathways and the deposition of mineralization products during the curing process was elucidated from a micro-to-mesoscale perspective. These findings provide a theoretical basis for optimizing the engineering design of CO2 mineralization and sequestration in coal-based solid waste cemented backfill.