In-situ cementation backfill of alkali-inspired ultrafine copper tailings: Performance and principles

Abstract

Ultrafine copper tailings (UTCT) are a type of bulk solid waste containing heavy metals, discharged from copper refining industries. Large stockpiles of these tailings pose significant environmental risks and lead to the wastage of valuable mineral resources. To address this issue, this study has developed a backfill material (solidified ultrafine copper tailings, S-UTCT) for mine shaft rehabilitation. This material utilizes waste alkali exciters and UTCT as base components. The primary process involves thoroughly mixing the alkali exciter with UTCT, followed by injection into a mold or pit for curing. The optimized process parameters are as follows: UTCT solid content of 50wt%–60wt%, mixing duration of 6–8 min, alkali activator dosage of 30wt%–35wt%, water-to-solid weight ratio of 0.2, mixing speed of 400 r/min, and curing period of 28 d. Mechanistic analysis revealed that the alkali activator induces mineral phase reconstruction and morphological reconfiguration of UTCT, driven by mechanochemical activation during ball milling. This results in improved compressive strength and effective immobilization of heavy metals. This paper presents a novel cement-free and burn-free method for preparing cementitious materials for recycling resources in mines.

Keywords

Ultrafine copper tailings / Alkali activation / Waste alkali / Cementitious material / Mine rehabilitation

References

[1] L.R. Adrianto, L. Ciacci, S. Pfister, S. Hellweg, Toward sustainable reprocessing and valorization of sulfidic copper tailings: scenarios and prospective LCA, Sci. Total Environ. 871 (2023) 162038.

[2] L.R. Adrianto, S. Pfister, Prospective environmental assessment of reprocessing and valorization alternatives for sulfidic copper tailings, Resour. Conserv. Recycl. 186 (2022) 106567.

[3] L.R. Adrianto, S. Pfister, S. Hellweg, Regionalized life cycle inventories of global sulfidic copper tailings, Environ. Sci. Technol. 56 (7) (2022) 4553-4564.

[4] B.D. Chen, Y.G. Zhu, J. Duan, X.Y. Xiao, S.E. Smith, Effects of the arbuscular mycorrhizal fungus Glomus mosseae on growth and metal uptake by four plant species in copper mine tailings, Environ. Pollut. 147 (2) (2007) 374-380.

[5] F. Chen, L.L. Liu, J.J. Chen, W.W. Li, Y.P. Chen, Y.J. Zhang, J.H. Wu, S.C. Mei, Q. Yang, H.Q. Yu, Efficient decontamination of organic pollutants under high salinity conditions by a nonradical peroxymonosulfate activation system, Water Res. 191 (2021) 116799.

[6] W. Chen, S.H. Yin, G.M. Zhou, Z.K. Li, Q. Song, Copper recovery from tailings through bioleaching and further application of bioleached tailings residue: comprehensive utilization of tailings, J. Clean. Prod. 332 (2022) 130129.

[7] R. Dandautiya, A.P. Singh, Utilization potential of fly ash and copper tailings in concrete as partial replacement of cement along with life cycle assessment, Waste Manag. 99 (2019) 90-101.

[8] J.R. Lan, Y. Sun, H. Tian, W. Zhan, Y.G. Du, H.P. Ye, D.Y. Du, T.C. Zhang, H.B. Hou, Electrolytic manganese residue-based cement for manganese ore pit backfilling: performance and mechanism, J. Hazard. Mater. 411 (2021) 124941.

[9] C.Y. Du, S.J. Yang, D.H. Ding, T.M. Cai, R.Z. Chen, Origin of synergistic effect between Fe/Mn minerals and biochar for peroxymonosulfate activation, Chem. Eng. J. 453 (2023) 139899.

[10] J.R. Lan, S.S. Zhang, Y.Q. Dong, J.H. Li, S.Y. Li, L. Feng, H.B. Hou, Stabilization and passivation of multiple heavy metals in soil facilitating by pinecone-based biochar: mechanisms and microbial community evolution, J. Hazard. Mater. 420 (2021) 126588.

[11] J.R. Lan, S.S. Zhang, T. Mei, Y.Q. Dong, H.B. Hou, Mechanochemical modification of electrolytic manganese residue: ammonium nitrogen recycling, heavy metal solidification, and baking-free brick preparation, J. Clean. Prod. 329 (2021) 129727.

[12] P.J. Duan, X. Xu, K.Y. Guo, Q.Y. Yue, B.Y. Gao, Peroxymonosulfate activation on a chainmail catalyst via an electron shuttle mechanism for efficient organic pollutant removal, Appl. Catal. B Environ. 316 (2022) 121695.

[13] J.Q. Liu, R.Y. Zhou, J.X. Yu, L. Guo, X.D. Li, C.Q. Xiao, H.B. Hou, R. Chi, G.Q. Feng, Simultaneous removal of lead, manganese, and copper released from the copper tailings by a novel magnetic modified biosorbent, J. Environ. Manag. 322 (2022) 116157.

[14] K. Ibebunjo, Y.El Ouardi, J.K. Bediako, A. Iurchenkova, E. Repo, Functionalization of recycled polymer and 3D printing into porous structures for selective recovery of copper from copper tailings, Chem. Eng. Sci. 286 (2024) 119664.

[15] C. Pan, Y. Sun, Y.Q. Dong, H.B. Hou, M.F. Kai, J.R. Lan, Efficient carbamazepine degradation by modified copper tailings and PMS system: performance evaluation and mechanism, J. Hazard. Mater. 465 (2024) 133198.

[16] B. Fränkle, T. Sok, M. Gleiß, H. Nirschl, Copper tailings filtration: Influence of filter cake desaturation, Miner. Eng. 217 (2024) 108952.

[17] H.S. Meng, C. Chen, Z.R. Yan, X.Y. Li, J. Xu, G.P. Sheng, Co-doping polymethyl methacrylate and copper tailings to improve the performances of sludge-derived particle electrode, Water Res. 165 (2019) 115016.

[18] C.L. Chen, H. Liu, Y. Zhang, G.H. Gu, J.Y. Hu, Micro-assessment of heavy metal immobilization within alkali-activated copper tailings-slag geopolymer, Cem. Concr. Compos. 149 (2024) 105510.

[19] F. Vargas, M. Lopez, Development of a new supplementary cementitious material from the activation of copper tailings: mechanical performance and analysis of factors, J. Clean. Prod. 182 (2018) 427-436.

[20] Y.D. Dong, Y. Zeng, Z.B. Hua, C.W. Wang, T. Yue, W. Sun, H.H. Tang, Enhancing solid-liquid separation performance of copper tailings by regulating settling floc properties, J. Clean. Prod. 460 (2024) 142610.

[21] F. Vargas, M. Lopez, L. Rigamonti, Environmental impacts evaluation of treated copper tailings as supplementary cementitious materials, Resour. Conserv. Recycl. 160 (2020) 104890.

[22] W. Xu, Y.Y. Zhang, J. Yan, Z.F. Chen, Q. Wei, H.Y. Wang, Y. Lu, Microstructure and properties of high-strength lightweight ceramsites customised with ultra-fine copper tailings, Constr. Build. Mater. 429 (2024) 136433.

[23] K.S. Al-Jabri, M. Hisada, A.H. Al-Saidy, S.K. Al-Oraimi, Performance of high strength concrete made with copper slag as a fine aggregate, Constr. Build. Mater. 23 (6) (2009) 2132-2140.

[24] A.X. Wu, Y. Wang, Z.E. Ruan, B.L. Xiao, J.D. Wang, L.Q. Wang, Key theory and technology of cemented paste backfill for green mining of metal mines, Green Smart Min. Eng. 1 (1) (2024) 27-39.

[25] W.H. Choi, S.R. Lee, J.Y. Park, Cement based solidification/stabilization of arsenic-contaminated mine tailings, Waste Manag. 29 (5) (2009) 1766-1771.

[26] A. Frýbort, D. Všianský, J. Štulířová, J. Stryk, M. Gregerová, Variations in the composition and relations between alkali-silica gels and calcium silicate hydrates in highway concrete, Mater. Charact. 137 (2018) 91-108.

[27] Y. Kuwahara, A. Hanaki, H. Yamashita, A direct conversion of blast furnace slag to a mesoporous silica-calcium oxide composite and its application in CO₂ captures , Green Chem. 22 (12) (2020) 3759-3768.

[28] Z.H. Wu, Z. Feng, S.Y. Pu, C. Zeng, Y. Zhao, C. Chen, H.L. Song, X.H. Feng, Mechanical properties and environmental characteristics of the synergistic preparation of cementitious materials using electrolytic manganese residue, steel slag, and blast furnace slag, Constr. Build. Mater. 411 (2024) 134480.

[29] Y. Li, D. van Zyl, Experimental study on the overall settling behavior of copper tailings suspension, Miner. Eng. 208 (2024) 108580.

[30] S.W. Zhou, Y.G. Wei, S.Y. Zhang, B. Li, H. Wang, Y.D. Yang, M. Barati, Reduction of copper smelting slag using waste cooking oil, J. Clean. Prod. 236 (2019) 117668.

[31] Z.H. Zhang, H.J. Zhu, C.H. Zhou, H. Wang, Geopolymer from kaolin in China: an overview, Appl. Clay Sci. 119 (2016) 31-41.

[32] Y. Li, D. van Zyl, Study on segregation-impacted hindered settling of fine copper tailings using a modified Kynch’s approach, Miner. Eng. 206 (2024) 108507.

[33] Y.W. Xiang, J.R. Lan, Y.G. Cai, Y. Wang, Y.Q. Dong, H.B. Hou, Preparation of nickel-cobalt tailings-based cementing materials by mechano-chemical activation: performance and mechanism, Constr. Build. Mater. 408 (2023) 133836.

[34] A. Vigneshwari, J. Jayaprakash, A review on 3D printable cementitious material containing copper and iron ore tailings: material characterization, activation methods, engineering properties, durability, and microstructure behavior, Innov. Infrastruct. Solut. 9 (3) (2024) 74.

[35] L.X. Zhang, L.S. Liang, Y. Li, J. Chen, Z.Y. Cui, J.Y. Qiao, Z.Y. Zhang, Z.M. Wang, Q. Xu, C. Zhao, Preparation of lightweight foam glass-ceramics from copper slag tailings: secondary aluminum slag as pore-forming agent, Ceram. Int. 50 (21) (2024) 43699-43709.

[36] C. Naber, F. Bellmann, J. Neubauer, Influence of w/s ratio on alite dissolution and C-S-H precipitation rates during hydration, Cem. Concr. Res. 134 (2020) 106087.

[37] G.K. Sun, J.F. Young, R.J. Kirkpatrick, The role of Al in C-S-H: NMR, XRD, and compositional results for precipitated samples, Cem. Concr. Res. 36 (1) (2006) 18-29.

[38] C.L. Qu, Y.C. Wang, K. Yu, J.P. Zhao, Chemically modified copper tailings doped anti-UV ageing coating for flame retarding plywood through catalytic charring, Constr. Build. Mater. 425 (2024) 135957.

[39] J. Chang, A.F. Pan, Y.Z. Ma, Y. Sun, Enrichment of valuable metals from silver tailings using the alkali roasting-leaching method, Sep. Purif. Technol. 350 (2024) 127938.

[40] H. Zhou, H. Basarir, T. Poulet, W. Li, R.A. Kleiv, A. Karrech, Life cycle assessment of recycling copper slags as cement replacement material in mine backfill, Resour. Conserv. Recycl. 205 (2024) 107591.

[41] R. Hari, Y. Zhuge, K.M. Mini, Performance assessment of pervious concrete incorporated with calcium silicate hydrates (C-S-H) cultivated on rice husk ash substrates-a trend surface analysis interpretation, Constr. Build. Mater. 446 (2024) 138050.

[42] Y. Sun, J.R. Lan, Y.G. Du, Z. Li, X. Liao, D.Y. Du, H.P. Ye, T.C. Zhang, S.H. Chen, Efficient removal of heavy metals by synergistic actions of microorganisms and waste molasses, Bioresour. Technol. 302 (2020) 122797.

[43] Y. Sun, Z.Y. Wu, J.R. Lan, Y. Liu, Y.G. Du, H.P. Ye, D.Y. Du, Effect of sulfate-reducing bacteria (SRB) and dissimilatory iron-reducing bacteria (DIRB) coexistence on the transport and transformation of arsenic in sediments, Water Res. 270 (2025) 122834.

[44] Y.Q. Dong, Y.W. Xiang, H.B. Hou, H.J. Lu, J.R. Lan, Remediation of Pb-Cd contaminated soil using coal bottom ash-based geopolymer and coir: Soil remodeling and mechanism, J. Clean. Prod. 423 (2023) 138706.