Characterization and Environmental Risk Assessment of Coal-based Solid Waste Towards Underground Backfilling

Chen, Yaoping; Wang, Duiyu; Li, Zhaojing; Wen, Hao; Yang, Ke; Zhang, Lina

doi:10.1007/s12205-024-0557-y

Cited by 2 publications

(1 citation statement)

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“…After multi-source CSW is filled into underground space, it will be affected by groundwater soaking and leaching, and the environmental safety and stability of the backfill materials are unknown. Although some studies have shown that the toxicity and heavy metal leaching content of multi-source CSW are very low, and the pollution risk to the environment is controllable 52 , this depends on the material composition and source of multi-source CSW, and the environmental impact of large-scale underground backfilling with multi-source CSW are still unclear 53 . In this study, there is a lack of mine environmental risk assessment of multi-source CSW before and after filling underground space.…”

Section: Discussionmentioning

confidence: 99%

Mix proportion and microscopic characterization of coal-based solid waste backfill material based on response surface methodology and multi-objective decision-making

Zhao,

Yang,

et al. 2024

Sci Rep

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The mix proportion of multi-source coal-based solid waste (CSW) for underground backfilling affects transportation and support performance of backfill materials, and even the backfilling cost. In this study, the optimal mix proportion of desulfurization gypsum (DG), furnace bottom slag (FBS) and gasification fine slag (GFS) is determined by the Response Surface Methodology–Box Behnken Design (RSM-BBD). Then the fluidity, bleeding rate, 3-day strength, 7-day strength and preparation cost are evaluation indicators, the optimal mix proportion of backfill materials is determined by the multi-objective decision-making method (MDM). Finally, the microstructure of the backfill material with optimal mix proportion was studied by TGA, MIP, SEM–EDS and XRD. The results show that the mix proportion of CSW with the optimal comprehensive index is coal gangue (CG): coal fly ash (CFA): DG: FBS: GFS = 1:1.5:0.2:0.1:0.1, the mass concentration is 78%, and ordinary Portland cement (OPC)/CSW = 7.5%. The weight loss phenomenon of the backfill material with the optimal mix proportion occurs continuously during the heating process, mainly due to the evaporation of crystal water, structural water and hydroxyl water. There are dense narrow-necked pores in the backfill material, and the pore connectivity is poor. There is no hydration reaction occurs between CSW particles, and the strength increase of the backfill material mainly depends on the hydration reaction of cement. In ettringite, part of Al2O3 is replaced by SiO2, and part of CaSO4 is replaced by CaCO3. This study provides a reference for the engineering application of underground backfilling with multi-source CSW.

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Section: Discussionmentioning

confidence: 99%