Lightweight ceramsite made of recycled waste coal gangue &amp; municipal sludge: Particular heavy metals, physical performance and human health

To address the pollution problem of acid mine drainage (AMD) characterized by high concentrations of Fe2+, Mn2+, and SO42−, a combination of coal gangue (CG) and sulfate-reducing bacteria (SRB) was employed. The effects of coal-gangue dosage, SRB inoculation concentration, and temperature on AMD treatment with coal-gangue-loaded SRB were determined through single-factor experiments and response surface methodology (RSM) experiments. By considering the principles of adsorption isotherms, adsorption kinetics, and reduction kinetics, the removal mechanisms of SO42−, Fe2+, and Mn2+ in AMD using coal gangue-loaded SRB in the the Haizhou open-pit mine was revealed. The results showed that the overall effectiveness of the four types of coal-gangue-loaded SRB in repairing AMD was as follows: 3# CG-loaded SRB > 2# CG-loaded SRB > 1# CG-loaded SRB > 4# CG-loaded SRB, with coal-gangue-loaded SRB in the the Haizhou open-pit mine showing the best performance. According to the RSM test, the optimum conditions for repairing AMD with coal-gangue-loaded SRB in the open-pit mine were a coal-gangue dosage of 52 g, SRB inoculation concentration of 11.7%, and temperature of 33.4 °C. The order of factors affecting the removal of SO42− and Fe2+ from AMD by SRB loaded on coal gangue was SRB inoculation concentration > temperature > coal-gangue dosage. For Mn2+, the order of influence was temperature > SRB inoculation concentration > coal-gangue dosage. In the process of repairing Fe2+ with coal-gangue-loaded SRB in the the Haizhou open-pit mine, the biological activity metabolism of SRB played a leading role, while the adsorption isotherm of Mn2+ followed the Freundlich model. The adsorption kinetics of coal-gangue-loaded SRB in the the Haizhou open-pit mine for Fe2+ and Mn2+ in AMD conformed to Lagergren’s second-order kinetic model, while the reduction kinetics of SO42− conformed to a first-order reaction model.

Section: Introductionmentioning

confidence: 99%

Remediation of Acid Mine Drainage in the Haizhou Open-Pit Mine through Coal-Gangue-Loaded SRB Experiments

Dong

Gao

et al. 2023

“…Traditional coal mining modes often cause surface subsidence, destroy surface water bodies or buildings, and seriously damage the ecological environment of the mining area [1][2][3]. In addition, a large amount of gangue produced during coal mining forms huge gangue hills on the ground, which not only occupies land resources but also pollutes the environment [4,5]. For the purpose of protecting villages near the mining area from the impact of mining activities, coal resources buried beneath them are generally abandoned, which seriously affects the recovery rate of resources.…”

Section: Introductionmentioning

confidence: 99%

Strata Movement of Overburden-Separation Grouting Working Face and Its Influence on Gas Emission during Mining

Cao,

Liu,

Shi

et al. 2023

Due to its excellent effect of surface subsidence reduction, the overburden-separation grouting (OSG) technology has been widely applied to green mining. However, OSG changes the mine pressure, and the resultant gas emission in the stope remains unclear. Therefore, with the 22301 working face of Tunlan Coal Mine as an example, the overburden deformation and stress distribution in the absence and presence of OSG were studied through numerical simulation and on-site tests. Furthermore, the gas emission law in the stope was contrastingly analyzed. The following results were obtained. With the rise of grouting pressure (GP), the subsidence of strata above the separation layer decreases while that below the separation layer increases; the heave displacement of floor strata below the coal seam gradually decreases. OSG significantly changes the geometric shape and range of the overburden stress relief zone. As the GP rises, the gas enrichment area moves downward continuously and shrinks spatially. Horizontally, the ranges of the stress relief zone and the free space in the goaf shrink, while the range and compaction degree of the compaction area gradually grow. After OSG, the total amount of gas emission in the working face falls by 52.2%.

“…The annual emission of CG, FA, and CGS in China exceeds 680 Mt, 750 Mt, and 100 Mt, respectively [1][2][3]. The stockpiled CSWs occupy farmland and pollute the soil, water, and the atmosphere [4,5]. Therefore, the utilization of CSWs must be resolved.…”

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

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.