CO₂ mineralization grouting into fractured gangue voids in post-mining goaf

Abstract

The treatment of post-mining goafs presents a significant challenge for the coal industry, grappling with environmental safety and carbon neutrality goals. To address issues such as abandoned goafs, high carbon emissions, and conflicts in backfill operations during coal mining, this study proposes a CO₂ mineralization grouting method that targets voids in post-mining goafs. A two-stage mineralization process was designed with a focus on in-situ goaf grouting using open-pore materials. Grouting materials were prepared from carbide slag and fly ash, with cetyltrimethylammonium bromide (CTAB) as a surfactant and oleic acid acts as a foam stabilizer to regulate the pore structure alongside hydrogen peroxide (H₂O₂) used to regulate the pore structure. Scanning electron microscopy, nuclear magnetic resonance, unconfined compressive strength tests, and random forest regression identified the optimal mix: CTAB = 1.2 g, oleic acid = 5.0 g, H₂O₂ = 1.0 g, water-to-solid ratio = 0.7, Si/Al and Na/Al molar ratios are controlled at 3.0 and 2.7, respectively. Results from custom-built testing devices showed that open-pore materials doubled the mineralization depth compared with closed-pore materials. The method demonstrates technical feasibility and economic viability, while emphasizing the importance of rigorous risk management to ensure environmental and operational sustainability. Compatible with existing green mining systems, it offers economic and environmental benefits, providing a novel approach for low-carbon coal mining.

Keywords

CO₂ storage and utilization / Coal mining goaf treatment / Mineralization grouting / Open pore acceleration / Sustainable mining

References

[1] R.S. Haszeldine, Carbon capture and storage: how green can black be? Science 325 (5948) (2009) 1647-1652.

[2] S.X. Sang, S.Q. Liu, Q.L. Zhu, S.J. Han, S.R. Zhang, K.L. Tan, X.Z. Zhou, S.J. Zheng, X. Wang, T. Liu, Research progress on technical basis of synergy between CO₂ geological storage potential and energy resources , J. China Coal Soc. 48 (7) (2023) 2700-2716.

[3] M.E. Boot-Handford, J.C. Abanades, E.J. Anthony, M.J. Blunt, S. Brandani, N. Mac Dowell, J.R. Fernández, M.C. Ferrari, R. Gross, J.P. Hallett, R.S. Haszeldine, P. Heptonstall, A. Lyngfelt, Z. Makuch, E. Mangano, R.T.J. Porter, M. Pourkashanian, G.T. Rochelle, N. Shah, J.G. Yao, P.S. Fennell, Carbon capture and storage update, Energy Environ. Sci. 7 (1) (2014) 130-189.

[4] C.G. Qian, Z.C. Wang, Y. Wen, Y.X. Mao, C.Q. Li, F. Yuan, Z.M. Sun, Highly efficient CO₂ capture on acid-treated sepiolite impregnated with mixed polyethyleneimine and diethanolamine , Green Smart Min. Eng. 1 (4) (2024) 363-374.

[5] Y.P. Zhang, G.X. Zhan, Z.L. Huang, L. Xing, Y.M. Ying, Z. Chen, J.H. Li, Performance and mechanisms of alkaline solid waste in CO₂ mineralization and utilization , Waste Manag. 175 (2024) 62-72.

[6] T. Teng, S.Q. Yang, Y.X. Zhao, L.F. Cui, J. Zhang, Quantitative determination of CH₄ production and CO₂ storage in coal mine goaf: a CO₂-ECBM recovery model that considers zonal permeability , Green Smart Min. Eng. 2 (2) (2025) 98-108.

[7] A. Sanna, M. Uibu, G. Caramanna, R. Kuusik, M.M. Maroto-Valer, A review of mineral carbonation technologies to sequester CO₂ , Chem. Soc. Rev. 43 (23) (2014) 8049-8080.

[8] M.H. Rasool, M. Ahmad, M. Ayoub, Selecting geological formations for CO₂ storage: a comparative rating system , Sustainability 15 (8) (2023) 6599.

[9] T. Li, Y. Gao, J.R. Zhang, D.X. Li, W. Chen, P. Zhang, B. Li, A.R. Mei, Experimental study on reconstruction of aquiclude by MICP under the background of water preserved coal mining in Northern Shaanxi, J. China Coal Soc. 46 (9) (2021) 2984-2994.

[10] X.B. Su, W.Z. Zhao, Q. Wang, Y.X. Zhou, L.F. Wang, Key technologies of microbial mining residual coal and CO₂-fly ash co-filling in the impacted geological body of coal mining , J. China Coal Soc. 49 (1) (2024) 400-414.

[11] E. Ranaee, R. Khattar, F. Inzoli, M.J. Blunt, A. Guadagnini, Assessment and uncertainty quantification of onshore geological CO₂ storage capacity in China , Int. J. Greenh. Gas Control 121 (2022) 103804.

[12] S. Valluri, V. Claremboux, S. Kawatra, Opportunities and challenges in CO₂ utilization , J. Environ. Sci. 113 (2022) 322-344.

[13] W. Seifritz, CO₂ disposal by means of silicates , Nature 345 (6275) (1990) 486.

[14] L. Ji, Carbon Dioxide Sequestration by Mineralisation of Coal Fly Ash (Dissertation), China University of Mining and Technology (Beijing), Beijing, China, 2018.

[15] K.S. Lackner, D.P. Butt, C.H. Wendt, Progress on binding CO₂ in mineral substrates , Energy Convers. Manag. 38 (1997) S259-S264.

[16] K.S. Lackner, C.H. Wendt, D.P. Butt, E.L. Joyce, D.H. Sharp, Carbon dioxide disposal in carbonate minerals, Energy 20 (11) (1995) 1153-1170.

[17] S.Q. Zhang, T. Zhao, K.Q. Li, W. Ni, H.F. Yang, Z.P. Wu, J. Li, Y. Li, B. Zhang, J.J. Wang, R.S. Xu, X.M. Liu, P.F. Fu, W.H. Cui, J. Yao, Effect of blast furnace slag substitution for cement in carbon-reduced and low-cost solidified/stabilized cementitious materials, Green Smart Min. Eng. 1 (1) (2024) 104-117.

[18] P. Librandi, P. Nielsen, G. Costa, R. Snellings, M. Quaghebeur, R. Baciocchi, Mechanical and environmental properties of carbonated steel slag compacts as a function of mineralogy and CO₂ uptake , J. CO₂ Util. 33 (2019) 201-214.

[19] M. Azadi, M. Edraki, F. Farhang, J. Ahn, Opportunities for mineral carbonation in Australia’s mining industry, Sustainability 11 (5) (2019) 1250.

[20] B.T. Qin, L.L. Feng, X. Shao, Mineralization of CO₂ from power plant flue gas by fly ash: technology and key scientific issues , J. China Coal Soc. 49 (2) (2024) 1161-1173.

[21] S.M. Lee, S.M. Yeon, S.P. Jung, Evaluation of accelerated mineral carbonation efficiency using industrial by-products and estimation of its domestic carbon dioxide reduction potential, J. Korean Soc. Environ. Eng. 44 (1) (2022) 21-30.

[22] J. Kim, H. Jang, Closed-loop recycling of C&D waste: mechanical properties of concrete with the repeatedly recycled C&D powder as partial cement replacement, J. Clean. Prod. 343 (2022) 130977.

[23] Z.M. Chen, R. Li, X.M. Zheng, J.X. Liu, Carbon sequestration of steel slag and carbonation for activating RO phase, Cem. Concr. Res. 139 (2021) 106271.

[24] Y.P. Zhang, L.P. Cui, Y.F. Liu, H.W. Li, Z.Q. Wang, Z.X. Lang, Comparison of three typical industrial solid wastes on the performance of CO₂ mineralization and sequestration , Chin. J. Environ. Eng. 15 (7) (2021) 2344-2355.

[25] G.H. Cao, L.Q. Ma, I. Ngo, A.E. Osemudiamhen, Z.Z. Guo, Experimental investigation on the combination of enzyme-induced calcium carbonate precipitation and organic materials for underground backfilling preparation, Minerals 14 (2) (2024) 153.

[26] J.X. Zhang, N. Zhou, F. Gao, H. Yan, Method of gangue grouting filling in subsequent space of coal mining, J. China Coal Soc. 48 (1) (2023) 150-162.

[27] S.J. Chen, L.B. Zhang, N. Jiang, D.W. Yin, Z.Y. Gao, W.J. Guo, АA. ХOРЕШOК, A case of large buildings construction above oldmine goaf in Shandong Province, J. China Coal Soc. 47 (3) (2022) 1017-1030.

[28] L. Zhu, T.Q. Song, W.Z. Gu, K. Xu, Z.C. Liu, F.Q. Qiu, C.F. Yuan, Experimental study on transportation resistance characteristics of gangue slurry and flow law in goaf, J. China Coal Soc. 47 (S1) (2022) 39-48.

[29] W.Z. Liu, Z.J. Hu, C. Liu, X.P. Huang, J.F. Hou, Mechanical properties under triaxial compression of coal gangue-fly ash cemented backfill after cured at different temperatures, Constr. Build. Mater. 411 (2024) 134268.

[30] K.P. Yu, L.Q. Ma, I. Ngo, J.T. Zhai, Y.J. Xu, Z.Y. Zhao, H. Wang, D.L. Wang, Gangue grouting filling in subsequent space of coal green mining: methodology and case study, Environ. Earth Sci. 83 (7) (2024) 217.

[31] M. Mareya, L. Tchadjie, T. Sithole, Turning fly ash and waste gypsum into a resource for backfilling applications, Case Stud. Constr. Mater. 20 (2024) e02703.

[32] L.J. Guo, X.P. Peng, Q.Q. Wang, Y. Zhao, L.L. Xu, S. Wu, Research progress on carbon dioxide mineralization sequestration technology by tailings, Green Smart Min. Eng. 1 (3) (2024) 307-321.

[33] M. Wang, L. Liu, B. Zhang, X.Y. Zhang, C. Huan, Y.J. Zhao, B.B. Tu, Basic theory of cold load and storage functional backfill in mining, J. China Coal Soc. 45 (4) (2020) 1336-1347.

[34] L. Liu, J. Xin, B. Zhang, X.Y. Zhang, M. Wang, H.F. Qiu, L. Chen, Basic theories and applied exploration of functional backfill in mines, J. China Coal Soc. 43 (7) (2018) 1811-1820.

[35] S.G. Li, J.F. Zhang, H.F. Lin, R.Y. Bao, Y. Ding, Y. Bai, Y.X. Zhou, B. Zhu, Research on the characteristics of CO₂-water interface and the law of dissolution and mass transfer under the condition of carbon sequestration in goaf , J. China Coal Soc. 49 (1) (2024) 513-527.

[36] S.M. Wang, Y.J. Shen, Q. Sun, L. Liu, Q.M. Shi, M.B. Zhu, B. Zhang, S.D. Cui, Underground CO₂ storage and technical problems in coal mining area under the “dual carbon” target , J. China Coal Soc. 47 (1) (2022) 45-60.

[37] L. Liu, S.M. Wang, M.B. Zhu, B. Zhang, D.Z. Hou, C. Huan, Y.J. Zhao, X.Y. Zhang, X.L. Wang, M. Wang, CO₂ storage-cavern construction and storage method based on functional backfill , J. China Coal Soc. 47 (3) (2022) 1072-1086.

[38] H.P. Xie, J.X. Zhang, F. Gao, B.Y. Li, C.B. Li, Y.C. Xie, N. Zhou, Theory and technical conception of carbon-negative and high-efficient backfill mining in coal mines, J. China Coal Soc. 49 (1) (2024) 36-46.

[39] T. Vamsi Nagaraju, S. Mantena, R. Gobinath, S. Bonthu, S.S. Alisha, Geopolymer-stabilized soils: influencing factors, strength development mechanism and sustainability, J. Taibah Univ. Sci. 17 (1) (2023) 2248651.

[40] D. Khale, R. Chaudhary, Mechanism of geopolymerization and factors influencing its development: a review, J. Mater. Sci. 42 (3) (2007) 729-746.

[41] F.A. Shilar, S.V. Ganachari, V.B. Patil, B.E. Bhojaraja, T.M. Yunus Khan, N. Almakayeel, A review of 3D printing of geopolymer composites for structural and functional applications, Constr. Build. Mater. 400 (2023) 132869.

[42] X.J. Du, G.R. Feng, M. Zhang, Z.H. Wang, W.H. Liu, Influence of backfilling rate on the stability of the “backfilling body-immediate roof” cooperative bearing structure, Int. J. Min. Sci. Technol. 32 (6) (2022) 1197-1206.

[43] Z.Y. Fang, Y.H. Gao, W. He, M.B. Zhu, L. Xia, P.Y. Yang, D.S. Liu, J. He, Carbonation curing of magnesium-coal slag solid waste backfill material: study on properties of flow, mechanics and carbon sequestration, Case Stud. Constr. Mater. 20 (2024) e03204.

[44] T.Q. Jiang, X.X. Cao, H.Y. Duan, K.Q. Shu, Recycling efficiency mechanism of recycled concrete aggregate to improve the CO₂ uptake and anti-leakage properties of CO₂ sequestration functional backfills , Constr. Build. Mater. 458 (2025) 139663.

[45] D.M. Huang, X.Z. Wang, X.K. Chang, S.Y. Qiao, H.H. Lu, X. Pan, Evolution law study of pore and fracture of coal gangue cemented filling body under axial compression using PFC2D, Constr. Build. Mater. 411 (2024) 134340.

[46] L.L. Shen, W.N. Lai, J.X. Zhang, Z.H. Sun, M. Li, N. Zhou, Mechanical properties and micro characterization of coal slime water-based cementitious material-gangue filling: a novel method for co-treatment of mining waste, Constr. Build. Mater. 408 (2023) 133747.

[47] C.W. Dong, N. Zhou, G.A. Ferro, H. Yan, J.F. Xu, H.D. Wang, S.X. Liu, Z.G. Zhang, Research on proportion and performance optimization of pure gangue backfilling slurry based on multi-objective differential evolution algorithm, Constr. Build. Mater. 418 (2024) 135432.

[48] C. Li, J.R. Bai, Y. Jiang, H.G. Xiao, W. Wang, F. Xu, Investigating the seepage control and plugging capabilities of polyurethane-cement composites: a comprehensive study on material properties, Constr. Build. Mater. 416 (2024) 135191.

[49] X. Bian, F.Y. Zhao, L.L. Zeng, Z.L. Ren, X.Z. Li, Role of superabsorbent polymer in compression behavior of high water content slurries, Acta Geotech. 19 (9) (2024) 6163-6178.

[50] M. Li, Y.G. Yan, H.Y. Dai, Z.J. Zhang, Study on rock and surface subsidence laws of super-high water material backfilling and mining technology: a case study in Hengjian coal mine, Sustainability 15 (11) (2023) 8713.

[51] H.Z. Li, G.L. Guo, S.C. Zhai, Mining scheme design for super-high water backfill strip mining under buildings: a Chinese case study, Environ. Earth Sci. 75 (12) (2016) 1017.

[52] J.X. Zhang, B.Y. Li, Y.C. Xie, C.B. Li, N. Zhou, Y.M. Guo, Z.J. Li, H.P. Xie, Carbon negative backfill mining in coal mines for carbon neutralization: chemical carbon fixation performances with mineralized gangue, Int. J. Rock Mech. Min. Sci. 186 (2025) 106016.

[53] Y. Ju, X.D. Nie, Y. Zhu, K. Wang, H.W. Zhou, S.R. Ge, Stress distribution and roof subsidence of surrounding strata considering in situ coal conversion and CO₂ mineralization backfilling: photoelastic experiments using 3D-printed models of mining faces and goafs , Sci. Total Environ. 912 (2024) 169368.

[54] Z.S. Tian, C.Q. Fu, H.L. Ye, How does carbonation of alkali-activated slag and Portland cement systems impact steel corrosion differently? Cem. Concr. Res. 181 (2024) 107528.

[55] K. Lyu, N. Jiang, D.W. Yin, S.Y. Meng, Z.Y. Gao, T. Lyu, Deterioration of compressive properties of coal rocks under water and gas coupling, J. Cent. South Univ. 31 (2) (2024) 477-495.

[56] S.T. Ji, X.P. Lai, F. Cui, Y. Liu, R.K. Pan, J. Karlovšek, The failure of edge-cracked hard roof in underground mining: an analytical study, Int. J. Rock Mech. Min. Sci. 183 (2024) 105934.