Effect of Incorporating Waste Limestone Powder into Solid Waste Cemented Paste Backfill Material

The conveying distance during the backfill operation has become extensively large with the advancement of mining work. It requires the immediate attention of academic and industrial communities. Adding air entraining agent (AEA) can improve the rheological properties of the filling slurry and facilitat the filling slurry transfer to the long-distance underground stope. The AEA can generate a large number of tiny bubbles, which acted as floating balls and reduced the friction between the particles. In addition, AEA acted as a dispersing and wetting agent. Herein, we have obtained filling material from the Sanning mine (Hubei, China) and utilized sodium abietate (SA) and triterpenoid saponins (SJ), as air entraining agents, to improve the fluidity of filling slurry. The influence of AEA content on mechanical properties, structure and morphology has been analyzed by uniaxial compressive strength (UCS) testing, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The results reveal that the addition of AEA increased the fluidity of filling slurry. Moreover, UCS of the AEA-free cemented paste backfill (CPB) sample, cured for 28 days, was found to be 2.23 MPa. However, the addition of 0.2% AEA (SA and SJ) increased the UCS to 2.31 MPa and 2.35 MPa, respectively. However, when SA and SJ amount was increased to 0.6%, UCS decreased to 2.19 MPa and 2.13 MPa, respectively. Hence, UCS of the CPB initially increased with the addition of AEA, followed by a gradual decrease, which can be ascribed to the pore structure inside CPB. One should note that the presence of AEA increased the number of small pores inside the CPB. The SEM results shows that pore structure of CPB can be optimized by adding an optimal proper amount of AEA. INDEX TERMS Air entraining agent, nuclear magnetic resonance, cemented paste backfill, uniaxial compressive strength: scanning electron microscope, rheological behavior.

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“…Based on NMR theory [23], the relationship between the value of relaxation time (T 2 ) and pores can be expressed as:…”

Section: Nmr Resultsmentioning

confidence: 99%

Influence of Air Entraining Agent on Strength and Microstructure Properties of Cemented Paste Backfill

Kuang

Zhou

et al. 2019

IEEE Access

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“…Silicon dioxide (SiO2), Aluminum oxide (Al2O3), Ferric oxide (Fe2O3), Calcium oxide (CaO), Magnesium oxide (MgO), and Sulfur trioxide (SO3) are the significant components of the tailing material, as shown in Table 1. The particle size of raw materials and the chemical composition play a significant role in the cemented paste's backfill hardened-specimens strength [68]. The MASTERSIZER 3000 particle size analyzer was applied in this investigation to obtain a high accuracy for the size distribution of the studied fine-grained materials depending on the laser diffraction technology.…”

Section: Chemical Compositionmentioning

confidence: 99%

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

2023

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Cement global demand shows continued growth and a significant increase in the production volume, which may negatively impact the non-renewable natural resources and the environment, which is incompatible with sustainability goals. Cement kiln dust (CKD) is a primary concern associated with clinker manufacturing as a waste byproduct. Similarly, the mining industry produces copper tailing as unwanted material while beneficiating the ore, creating environmental problems due to difficulty in managing worldwide generated quantities that reach billions of metric tons. This study investigated the beneficial utilization of cement kiln dust and copper tailing as undesirable wastes in industrial applications through underground mines’ cemented paste backfill (CPB). Sixty different mixtures were prepared with three types of CKD collected from various cement manufacturers and were accordingly used with a proportion of 5, 10, and 15% to partially replace ordinary Portland cement (OPC) and pozzolan Portland cement (PPC) binders, represented in hundreds of CPB samples. The hardened specimens were subjected to density, uniaxial compressive strength (UCS), and axial deformation measurements to evaluate the physical and mechanical properties at curing up to 90 days. Meanwhile, X-ray powder diffraction (XRD) was extensively applied to chemically investigate the hydration products of CPB-hardened mixtures. Moreover, we developed a UCS predictive model applying two techniques: multiple variables regression analysis and artificial neural network (ANN). The results showed that the tricalcium silicate (Alite) and dicalcium silicate (Belite) phases form C-S-H upon hydrations and provide high strength in the binary mixtures. Meanwhile, the CKD’s lime saturation factor (LSF) governed the strength value in the ternary mixtures that utilized copper tailings. That makes CKD practical in the CPB mixture when partially replacing the OPC and PPC binders, with a proportion of up to 15%. In addition, the ANN technique’s predictive model exhibited a significant positive correlation with excellent statistical parameters that achieved 0.995, 0.065, and 0.911 for R2, RMSE, and MAE, respectively.

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“…Therefore, the utilization of CSWs must be resolved. Backfill mining is an environmental mining technology that offers the advantages of rock strata movement control [6], underground water protection [7], and solid waste utilization [8,9]. Consequently, it has received considerable attention in the research on coal mining.…”

Section: Introductionmentioning

confidence: 99%

Effect of CO2 Mineralization on the Composition of Alkali-Activated Backfill Material with Different Coal-Based Solid Wastes

Huo

Zhang

et al. 2023

Sustainability

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Research focusing on waste management and CO2 mineralization simultaneously has been a popular topic in the mining community, and a common approach is to mineralize CO2 with coal-based solid waste (CSW, e.g., gangue (CG), fly ash (FA), coal gasification slag (CGS)) produced by mining activities. Despite the understanding of CO2 mineralization by cementitious materials, the mineralization capacity of alkali-activated CSWs remains unknown. Therefore, the mineral composition evolution and mineralization capacity of different alkali-activated materials (prepared with CG, FA, CGS, and sodium hydroxide (which works as the alkali-activator), respectively) are investigated with the adoption of Gibbs Energy Minimization Software (GEMS). The results indicate that the abovementioned three alkali-activated CSWs are majorly composed of calcium silicate hydrate, magnesium silicate hydrate, kaolinite, sodium zeolite, and liquid. Due to the difference in the chemical composition of different CSWs, the amount of hydration products varies. Specifically, the alkali-activated CSWs made with CGS have the maximum calcium silicate hydrate (C-S-H), while those prepared with FA enjoy the lowest porosity. In addition, the CO2 mineralization process will result in the formulation of carbonate and, theoretically, the maximum quantity of mineralized CO2 is less than 20% of the binder used. Furthermore, compared with CG and CGS, FA is characterized with the highest mineralization capacity. The findings in this study contribute to the understanding of CO2 mineralization with alkali-activated CSWs.

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Effect of Incorporating Waste Limestone Powder into Solid Waste Cemented Paste Backfill Material

Cited by 10 publications

References 20 publications

Influence of Air Entraining Agent on Strength and Microstructure Properties of Cemented Paste Backfill

Influence of Air Entraining Agent on Strength and Microstructure Properties of Cemented Paste Backfill

Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill

Effect of CO2 Mineralization on the Composition of Alkali-Activated Backfill Material with Different Coal-Based Solid Wastes

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