The large coal production and consumption has caused environmental problems worldwide as a source of energy production with irreparable effects on soil, water, and the ecosystem. In addition, producing coal waste in coal washing plants and burying it intensifies the issue in nature. Due to the rising generation of coal waste from various sources, this study utilized several forms of coal waste obtained from a coal-washing plant in the production of both structural concrete (with a water-cement ratio of 0.54) and non-structural concrete (with a water-cement ratio of 0.7). The impact of coal waste on compressive strength (CS) was examined at curing ages of 7, 28, and 56 days. Various percentages of coal waste were substituted for both cement and sand. A superplasticizer was incorporated into the concrete mixtures to enhance the workability and achieve the desired slump and strength levels. According to the compressive strength findings, the ideal replacement level of sand with jig coal waste was 30 %. For 56-day-old specimens, the optimal substitution rates for cement with jig coal waste powder, flotation coal waste, and coal waste ash were found to be 10 %, 10 %, and 20 %, respectively. Notably, adding 10 % coal waste powder and coal waste ash increased compressive strength by 22 %, 23 %, and 44 % at 56 days.

This study examines the key drivers behind the continued reliance on traditional biomass fuels such as charcoal and firewood in urban areas of developing countries, including the city of Lubumbashi. The paper focuses on economic constraints, health problems associated with the use of these fuels, the environmental consequences of growing use and also looks at the alternatives for cooking and their accessibility. The various reasons behind the growing and constant use of charcoal and firewood are examined in the context of the city of Lubumbashi and other developing countries. However, the continuous supply of charcoal and firewood not only contributes to the degradation of forests and the extinction of species, but also disrupts the livelihoods of forest-dependent families and exacerbates soil erosion. The charcoal production process is intrinsically damaging to both the environment and human well-being. Not only does it emit large quantities of CO2, contributing to atmospheric pollution, but it also presents health risks for both producers and users. The smoke and soot generated during charcoal production expose people to harmful substances, leading to adverse health effects and even premature death, particularly among children. This review also discusses the impact of this production and use on the education of women and children, who are responsible for cooking and harvesting firewood, resulting in a higher illiteracy rate among women. Faced with the need to take global action to mitigate the impact of climate change, global carbon dioxide emissions must be drastically reduced to meet the Paris Agreement target of zero net emissions by 2050. A practical and sustainable solution is discussed in this review as an alternative to traditional cooking systems namely solar cooking, which offers enormous potential, provided it is accessible, and is an excellent alternative to the heavy reliance on biomass for household energy needs in developing countries.

The Upper Silesian Coal Basin faces ongoing challenges with self-heating in coal waste dumps, a problem that leads to dangerous and unpredictable subsurface fires. This study investigates the thermal dynamics and vegetation response in a coal waste dump, expanding on previous research that links waste temperatures with plant health and distribution. The study area-a small, old coal waste dump located in a highly urbanized area-was subjected to comprehensive environmental monitoring focused on various fire determinants. The findings confirm that coal waste dumps, regardless of size and complexity, experience similar fire determinants, with vegetation colonization progressing in bands starting with pioneer species in less heat-affected areas. As the distance from the fire zone increases, plant density and diversity improve, indicating a recovery in thermally stabilized zones. The study also demonstrates the repeatability of relationships between subsurface temperatures and vegetation status across different coal waste dumps, supporting the use of plants as indicators of underground fires. Elevated subsurface temperatures in thermally active zones lead to clear 'dying' and 'death' zones, where excessive heat damages plant roots, causing die-offs. In contrast, areas with moderate temperatures allow vegetation growth, even in winter, due to favourable root-zone conditions. The study highlights the need for improved monitoring and fire mitigation strategies to address thermal activity in reclaimed sites, especially those with limited historical data. These insights are crucial for preventing similar issues in the future and minimizing the long-term impacts on surrounding communities and ecosystems.

Aiming at mitigating the high risks associated with conventional explosive blasting, this study developed a safe directional fracturing technique, i.e. instantaneous expansion with a single fracture (IESF), using a coal-based solid waste expanding agent. First, the mechanism of directional fracturing blasting by the IESF was analyzed, and the criterion of directional crack initiation was established. On this basis, laboratory experiments and numerical simulations were conducted to systematically evaluate the directional fracturing blasting performance of the IESF. The results indicate that the IESF presents an excellent directional fracturing effect, with average surface undulation differences ranging from 8.1 mm to 22.7 mm on the fracture surfaces. Moreover, during concrete fracturing tests, the stresses and strains in the fracturing direction are measured to be 2.16-3.71 times and 8 times larger than those in the non-fracturing direction, respectively. Finally, the IESF technique was implemented for no-pillar mining with gob-side entry retaining through roof cutting and pressure relief in an underground coal mine. The IESF technique effectively created directional cracks in the roof without causing severe roadway deformation, achieving an average cutting rate and maximum roadway deformation of 94% and 197 mm, respectively. These on-site test results verified its excellent directional rock fracturing performance. The IESF technique, which is safe, efficient, and green, has considerable application prospects in the field of rock mechanics and engineering. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Currently, studies on the permeability evolution characteristics of overlying aquiclude protective layers caused by coal mining focus on single lithological protective layers and assume the permeability coefficient remains constant. However, these studies fail to consider the variation characteristics of the combination protective layer structure and permeability coefficient. Therefore, an analytical method is proposed to study coal seam leakage under mining conditions in the blown-sand beach region based on the structure and permeability coefficient of the combination protective layer. First, the stress path of the overlying combination aquiclude under coal mining disturbance is comprehensively considered. Based on this, triaxial loading and unloading seepage creep experiments are conducted with different proportions of overlying combination aquiclude. The analytical relationship between the permeability coefficient of the samples and loess proportion, stress level, and soil depth in the stress recovery stage is determined, leading to the establishment of a creep permeability coefficient evolution model for the overlying combination aquiclude of the coal seam under the stress path of coal mining. Second, the creep permeability coefficient evolution model is integrated with a fusion algorithm in COMSOL numerical simulation software. Numerical simulations are then performed to examine the evolution law of phreatic leakage during coal seam mining and recovery, revealing a relationship curve in which leakage gradually decreases over time before stabilizing in the post-mining recovery stage. Finally, based on mathematical and statistical methods, a phreatic leakage evolution model is developed for both mining and post-mining stages to provide a theoretical basis for environmental protection.

Mining leads to soil degradation and land subsidence, resulting in decreased soil quality. However, there are limited studies on the detailed effects of mining activities on soil properties, particularly in western aeolian sand. This study, therefore, quantitatively assessed the aeolian sandy soil disturbance induced by mining activities in the contiguous regions of Shanxi, Shaanxi, and Inner Mongolia. The following soil physical quality indices were measured in the pre (May 2015), mid (October 2015), and postmining period (April 2016), such as the soil water content (SWC), particle size (PS), soil penetration (SP), and soil saturated hydraulic conductivity (SSHC). The results showed that mining activities brought irreversible effects on soil structures. In the pre-mining period, land subsidence broke up large soil particles, destroying soil structure, leading to decreased PS (218.33 vs. 194.36 mu m), SP (4615.56 vs. 2631.95 kPa), and subsequently decreased SSHC (1.12 vs. 0.99 cm/min). Rainfall during the midmining period exacerbated this fragmentation. Thereafter, low temperatures and humidity caused the soil to freeze, allowing the small soil particles to merge into larger ones. Meanwhile, the natural re-sedimentation, subsidence, and heavy mechanical crushing in the post-mining period increased PS and SP. The SSHC hence increased to 1.21 cm/min. Furthermore, the evaluation of soil indices from different stress zones showed that the external pulling stress zone always had a higher SSHC than the neutral zone in any mining period, possibly due to the presence of large cracks and high SWC. This study contributes to the understanding of the impact of mining activities on soil physical qualities, providing a theoretical basis and quantitative guidance for the surface damage caused by coal mining in the aeolian sandy area in Western China.

Coal mining has significant economic and environmental implications. The extraction and combustion of coal release harmful chemicals and dust, impacting air, soil, and water quality, as well as natural habitats and human health. This study aimed to investigate the association between global DNA methylation, DNA damage biomarkers (including telomere length), and inorganic element concentrations in the blood of individuals exposed to coal mining dust. Additionally, polycyclic aromatic hydrocarbons were analyzed. The study included 150 individuals exposed to coal mining and 120 unexposed controls. Results showed significantly higher global DNA hypermethylation in the exposed group compared to controls. Moreover, in the exposed group, micronucleus frequency and age showed a significant correlation with global DNA hypermethylation. Blood levels of inorganic elements, including titanium, phosphorus, sodium, aluminum, iron, sulfur, copper, chromium, zinc, chlorine, calcium, and potassium, were potentially associated with DNA methylation and oxidative damage, as indicated by comet assay results. Furthermore, exposure to polycyclic aromatic hydrocarbons such as fluoranthene, naphthalene, and anthracene, emitted in mining particulate matter, may contribute to these effects. These findings highlight the complex interplay between genetic instability, global DNA hypermethylation, and environmental exposure in coal mining areas, emphasizing the urgent need for effective mitigation strategies.

The study investigates the interaction between geogrids and two distinct granular backfill materials, Yamuna sand and coal mine overburden through a combination of laboratory experiments and numerical simulations. It evaluates the physical and mechanical properties of coalmine overburden and Yamuna sand, and the pullout performance of geogrid embedded in both materials. A large-scale pullout box was utilised to conduct the experiments, and the results showed that coalmine overburden offers higher pullout resistance than Yamuna sand. The effect of physical parameters such as elasticity of geogrid, geogrid geometry and angle of inclination were analysed using the discrete element method. The pullout resistance of geogrids mainly depends on the elastic properties of the material. The study also shows the existence of an optimum spacing between longitudinal and transverse ribs.

The coal mining under the goaf of close-up room mining coal pillars is prone to chain instability and damage of the overlying coal pillars, aquifer damage, surface subsidence, soil erosion, vegetation withering, and other problems. In this paper, theoretical analysis was conducted on the stability of the remaining coal pillars in room mining, and numerical simulations were used to study the influence characteristics of the plastic zone, strain energy, and stress field of the overlying coal pillars during the mining of the lower close coal seam. The stability of the coal pillars under the influence of mining was analyzed with the safety factor. The proposed technologies of cemented paste backfilling on the ground and backfilling the goaf of the lower coal seam are applied, the influence of different water-cement ratios, aeolian sand, and cement content on the mechanical properties of backfilling materials was studied through experiments, and the stability of overlying coal pillars with different dimensions of the backfilling pier columns under certain ratio conditions was studied using numerical simulation method. The research results indicate that when the dimensions of the backfilling pier columns are 40 m x 40 m and the compressive strength is 3.12 MPa, the stability of the overlying coal pillar can be effectively controlled, achieving safe mining under the remaining coal pillar. The research results can provide new ideas for the mining of coal resources and environmental protection under the remaining coal pillar of room mining.

The massive accumulation of waste PET plastic (WP) and coal gangue (CG) would induce a series of environmental problems such as causing soil and water pollution. For reducing the environmental pollution induced by these two wastes, this study attempts to utilize the combination of WP and CG into cement-based materials. Cement mortars incorporated with fine waste plastic (FWP) replacing part of sand and concrete blended with CG and coarse waste plastic (CWP) as part of coarse aggregate were prepared and their work-ability, mechanical strengths, dynamic elastic modulus (DEM), chloride ion permeability, hydration and microstructures were systematically investigated. In addition, metakaolin (MK) as a kind of active admixture was added into mortar or concrete and its effect of MK on the property of cement mortar or concrete was evaluated. The results show that the strengths of cement mortars containing various level of FWP decrease with increase of FWP and CG level. The mechanical strengths of concrete containing MK and 25-100 % CG and CWP are appropriate at different ages. Although the strengths of concrete blended with MK and wastes aggregate are lower than that of concrete without wastes, it is obviously higher than that of concrete only containing wastes but not MK. Its slump of fresh concrete significantly declines with CWP and CG contents growth. The coulomb electric flux and chloride migration coefficient of concrete at 28d generally increase with CG and CWP level, which indicates a declined tendency of resistance to chloride ion penetration. Its DEM for concrete measured with ultrasonic testing method slightly decrease with rise of CG and CWP content (25-100 %) and can give a basic prediction of strengths and chloride ion permeability. Hydration and microstructures tests including TG/DTA, MIP and SEM/EDS demonstrate that the pozzolanic reaction of MK can result in more gels generated and strengthen the ITZ between WP or CG and cement paste thus evidently improving its mechanical and durability of concrete when compared to the reference specimen without MK. Although the properties of concrete blended with CG and CWP as part of coarse aggregate are inferior to pure natural gravel contained concrete, its strengths and resistance to chloride ion permeability can achieve requirements of engineering structures.