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A numerical simulation study was conducted using Ansys Fluent 2023 R1 simulation software to investigate the influence of coal dust on the overpressure of gas explosion. The results demonstrated that the reliability of the selected mathematical model was validated through comparisons across three data sources: (1) experimental data from a gas and coal dust explosion propagation test system, (2) experimental results from full-scale mine roadway tests reported in the literature, and (3) the current numerical simulation outcomes. Based on elemental and industrial analyses, the stoichiometric concentration for various coal dust explosions was determined, and a formula was established to calculate the actual mass concentration of coal dust participating in the explosion process. A conversion relationship between the equivalent ratio and the mass concentration of coal dust was developed for different coal types. The equivalent ratio is defined as the ratio of the stoichiometric air–fuel ratio to the actual air–fuel ratio, used to quantify whether reactants are in excess or deficiency. When the equivalence ratio Φ equals 1, the methane volume concentration is 9.5%. If the methane volume concentration is below this stoichiometric level, the addition of a small amount of coal dust enhances the explosion intensity. Conversely, when the methane concentration is equal to or exceeds the stoichiometric value, coal dust exerts an inhibitory effect on the gas explosion. When varying concentrations of fat coal dust were introduced into explosions with 7.5% methane, the maximum explosion pressure occurred at a coal dust concentration of 200 g/m³. At Φ = 1, the stoichiometric mass concentration of fat coal dust was calculated as 107.2 g/m³; however, the actual amount of coal dust involved in the reaction did not reach this theoretical value, indicating that the equivalent ratio-based concentration exceeded the stoichiometric concentration. When 7.5% methane reacted with oxygen, the residual oxygen could only support combustion corresponding to a stoichiometric coal dust concentration of approximately 29.7 g/m³, meaning that only about 29.7 g/m³ of the 200 g/m³ fat coal dust participated in the explosion. Under conditions of 7.5% gas concentration and 200 g/m³ coal dust concentration, smaller coal dust particle sizes resulted in higher explosion pressures. Furthermore, under identical experimental conditions, as the degree of coal metamorphism decreased—from lean coal to coking coal, fat coal, gas coal, and finally lignite—the peak overpressure of the gas–coal dust coupled explosion increased sequentially, indicating a negative correlation between explosion overpressure and the degree of coal metamorphism.

To promote the application of microbially induced mineralization technology in the field of coal dust suppression, two urease-producing bacteria were co-cultured, with the aim to define the influence of different culture conditions on the growth and urease activity of the bacteria. According to the results, when S. pasteurii and B. cereus CS1 were inoculated in succession at a volume ratio of 1:1 and an interval of 14 h, the mixed bacteria achieved optimal growth and had the highest urease activity; when the initial pH value of culture medium was 9 and the urea and Ca2+ concentrations in the substrate were uniformly 0.1 mol/L, the growth and urease activity of the mixed bacterial culture reached their peaks. SEM-EDS and XRD results indicated that, regardless of the specific urease-producing bacteria used (single urease-producing bacteria or the mixed urease-producing bacteria), their mineralization products were uniformly vaterite-type and calcite-type calcium carbonate; FTIR and thermogravimetric analysis also confirmed their mineralization products as calcium carbonate. By spraying the bacterial inoculants with a corresponding calcium source and urea on pulverized coal, it was found that the bacteria successfully survived and caused pulverized coal to be consolidated. In particular, the mixed bacterial inoculant manifested a stronger consolidation effect, with a wind erosion–induced mass loss of less than 20 g/(m2•h). We provide experimental support for the field of microbial coal dust suppression.

Background The characteristics of coal dust (CD) particles affect the inhalation of CD, which causes coal worker’s pneumoconiosis (CWP). CD nanoparticles (CD-NPs, < 500 nm) and micron particles (CD-MPs, < 5 μm) are components of the respirable CD. However, the differences in physicochemical properties and pulmonary toxicity between CD-NPs and CD-MPs remain unclear. Methods CD was analyzed by scanning electron microscopy, Malvern nanoparticle size potentiometer, energy dispersive spectroscopy, infrared spectroscopy, and electron paramagnetic resonance spectroscopy. CCK-8 assay, ELISA, transmission electron microscope, JC-1 staining, reactive oxygen species activity probe, calcium ion fluorescent probe, AO/EB staining, flow cytometry, and western blot were used to determine the differences between CD-NPs and CD-MPs on acute pulmonary toxicity. CCK-8, scratch healing and Transwell assay, hematoxylin–eosin and Masson staining, immunohistochemistry, immunofluorescence, and western blot were applied to examine the effects of CD-NPs and CD-MPs on pneumoconiosis. Results Analysis of the size distribution of CD revealed that the samples had been size segregated. The carbon content of CD-NPs was greater than that of CD-MPs, and the oxygen, aluminum, and silicon contents were less. In in vitro experiments with A549 and BEAS-2B cells, CD-NPs, compared with CD-MPs, had more inflammatory vacuoles, release of pro-inflammatory cytokines (IL-6, IL-1β, TNFα) and profibrotic cytokines (CXCL2, TGFβ1), mitochondrial damage (reactive oxygen species and Ca 2+ levels and decreased mitochondrial membrane potential), and cell death (apoptosis, pyroptosis, and necrosis). CD-NPs-induced fibrosis model cells had stronger proliferation, migration, and invasion than did CD-MPs. In in vivo experiments, lung coefficient, alveolar inflammation score, and lung tissue fibrosis score (mean: 1.1%, 1.33, 1.33) of CD-NPs were higher than those of CD-MPs (mean: 1.3%, 2.67, 2.67). CD-NPs accelerated the progression of pulmonary fibrosis by upregulating the expression of pro-fibrotic proteins and promoting epithelial–mesenchymal transition. The regulatory molecules involved were E-cadherin, N-cadherin, COL-1, COL-3, ZO-1, ZEB1, Slug, α-SMA, TGFβ1, and Vimentin. Conclusions Stimulation with CD-NPs resulted in more pronounced acute and chronic lung toxicity than did stimulation with CD-MPs. These effects included acute inflammatory response, mitochondrial damage, pyroptosis, and necrosis, and more pulmonary fibrosis induced by epithelial–mesenchymal transition.

Despite international efforts to limit worker exposure to coal dust, it continues to impact the health of thousands of miners across Europe. Airborne coal dust has been studied to improve risk models and its control to protect workers. Particle size distribution analyses shows that using spraying systems to suppress airborne dusts can reduce particulate matter concentrations and that coals with higher ash yields produce finer dust. There are marked chemical differences between parent coals and relatively coarse deposited dusts (up to 500 µm, DD 500 ). Enrichments in Ca, K, Ba, Se, Pb, Cr, Mo, Ni and especially As, Sn, Cu, Zn and Sb in the finest respirable dust fractions could originate from: (i) mechanical machinery wear; (ii) variations in coal mineralogy; (iii) coal fly ash used in shotcrete, and carbonates used to reduce the risk of explosions. Unusual enrichments in Ca in mine dusts are attributed to the use of such concrete, and elevated K to raised levels of phyllosilicate mineral matter. Sulphur concentrations are higher in the parent coal than in the DD 500 , probably due to relatively lower levels of organic matter. Mass concentrations of all elements observed in this study remained below occupational exposure limits.

To study the effects of coal dust particle size and mass of coal dust on gas-coal dust hybrid explosions, we conducted sedimentary gas-coal dust explosion experiments using a pipe network system that included multiple components and individual interactions, which were independently designed and constructed. Experimental conclusions were then theoretically verified based on factor response surface theory. The results demonstrated that when the particle size of coal dust was constant, the pressure peak, flame front velocity peak, and flame front temperature peak of the explosion initially increased and then decreased with increasing mass. When the mass of coal dust was constant, the pressure peak, flame front velocity peak, and flame front temperature peak of the explosion also initially increased and then decreased with increasing particle size. The mass and particle size values of the coal dust were 25 g and 48-52 μm, respectively, and under these conditions, the explosion was the most violent. The effects of mass on the pressure peak and flame front temperature peak were greater than the particle size of the coal dust, and the effect of particle size on the flame front velocity was greater than the mass of the coal dust.

The quest for scientifically advanced and sustainable solutions is driven by growing environmental and economic issues associated with coal mining, processing, and utilization. Consequently, within the coal industry, there is a growing recognition of the potential of microbial applications in fostering innovative technologies. Microbial-based coal solubilization, coal beneficiation, and coal dust suppression are green alternatives to traditional thermochemical and leaching technologies and better meet the need for ecologically sound and economically viable choices. Surfactant-mediated approaches have emerged as powerful tools for modeling, simulation, and optimization of coal-microbial systems and continue to gain prominence in clean coal fuel production, particularly in microbiological co-processing, conversion, and beneficiation. Surfactants (surface-active agents) are amphiphilic compounds that can reduce surface tension and enhance the solubility of hydrophobic molecules. A wide range of surfactant properties can be achieved by either directly influencing microbial growth factors, stimulants, and substrates or indirectly serving as frothers, collectors, and modifiers in the processing and utilization of coal. This review highlights the significant biotechnological potential of surfactants by providing a thorough overview of their involvement in coal biodegradation, bioprocessing, and biobeneficiation, acknowledging their importance as crucial steps in coal consumption.

Effective dust control is crucial for improving air quality and worker safety in underground mining operations, particularly in sealed excavation faces where traditional ventilation methods are insufficient. Understanding the behavior of coal dust in such environments is essential for developing targeted control strategies. Transitioning from ventilated to sealed tunneling dramatically changes dust dispersion dynamics. High-concentration dust (5,000 mg/m³) primarily diffuses along the roof toward the sidewalls and distal regions of the tunnel, rather than being dominated by airflow velocity and volume. Initial gas composition and dust particle size significantly impact dust concentration, with changes ranging from − 99% to + 1,216% and − 72% to + 169%, respectively. In contrast, methane emissions and temperature variations have limited effects on dust concentration. Based on these insights, we propose specific dust suppression strategies for sealed tunneling environments, offering practical solutions for dust control in similar mining scenarios.

Aiming at the three-body contact problem of mechanical rough surface containing wet coal dust interface, the three-body contact model of rough surface containing wet coal dust interface is constructed by comprehensively considering the contact deformation of rough surface and contact characteristics of wet coal dust, and based on the crushing theory. By analysing the contact force, load-bearing particle size and adjacent contact angle thresholds of the wet coal dust layer, the force chain identification criterion is formulated. Finally, quantitative calculations of the force chain characteristics are performed to reveal the effect of different initial porosities on the three-body contact stiffness, which is verified experimentally. The results of the study show that the average contact force of the wet coal dust layer can be used as the force chain contact force threshold, the average particle size can be used as the force chain particle size threshold, and the force chain angle threshold is determined by the particle coordination number. As the initial porosity decreases, the number, length and stiffness of force chains in the wet coal dust layer increase significantly, and the stiffness reaches a maximum value of 2.007 × 10 8  pa/m at the moment of downward pressure to stabilisation, while the trend of force chain bending varies in the opposite direction, and its minimum bending degree decreases to 20°. The maximum relative error between the simulation and experimental results of three-body contact stiffness is 9.64%, which proves the accuracy of the force chain identification criterion and the quantitative calculation of three-body contact stiffness by force chain.

The explosion of coal dust is powerful and has a wide range of spread, which can easily cause mass death and injury. In this paper, the flame microstructure and propagation characteristics of coal dust explosion are recorded by high-speed photography schlieren technique. The experimental results show that the flame shape of Hartmann outlet is mushroom cloud with obvious fractal characteristics, and the fractal dimension can measure its complexity. When the particle size of coal dust is constant, the fractal dimension increases first and then decreases with the increase of concentration. When the coal dust particle size is less than 53 μm and the initial concentration is 300 g/m 3 , the flame fractal dimension reaches the maximum value of 1.71. The fractal dimension decreases with the increase of coal dust particle size. The coal dust explosion flame has a cellular structure, and its instability is caused by the combined action of hydrodynamic instability and unequal diffusion instability. These instabilities make the flame front structure develop from wrinkles to cell bodies and change continuously. This study can reveal the complexity of coal dust explosion flame propagation at the outlet position, and provide a new perspective for in-depth understanding of coal dust explosion propagation behavior.

The ignition and explosion of coal dust are significant hazards in coal mines. In this study, the minimum ignition temperature and energy of non-stick coal dust were investigated empirically at different working conditions to identify the key factors that influence the sensitivity and characteristics of coal dust explosions. The results showed that for a given particle size, the minimum ignition temperature of the coal dust layer was inversely related to the thickness of the coal dust layer. Meanwhile, when the layer thickness was kept constant, the minimum ignition temperature of the coal dust layer decreased with smaller coal dust particle sizes. Over the range of particle sizes tested (25–75 μm), the minimum ignition temperature of the coal dust cloud gradually increased when larger particles was used. At the same particle size, the minimum ignition temperature of the coal dust layer was much lower than that of the coal dust cloud. Furthermore, the curves of minimum ignition energy all exhibited a minimum value in response to changes to single independent variables of mass concentration, ignition delay time and powder injection pressure. The interactions of these three independent variables were also examined, and the experimental results were fitted to establish a mathematical model of the minimum ignition energy of coal dust. Empirical verification demonstrated the accuracy and practicability of the model. The results of this research can provide an experimental and theoretical basis for preventing dust explosions in coal mines to enhance the safety of production.