Search Results (176)

Soil heavy metal contamination poses significant risks to ecological safety and human health, particularly in rapidly industrializing cities. Effectively identifying pollution sources is crucial for risk management and remediation. GIS coupled with data mining techniques, provide a powerful tool for quantifying and visualizing these sources. This study investigates the concentration, spatial distribution, and sources of heavy metals in urban soils of Bengbu City, an industrial and transportation hub in eastern China. A total of 139 surface soil samples from the urban core were analyzed for nine heavy metals. Using integrated GIS and PCA-APCS-MLR data mining techniques, we systematically determined their contamination characteristics and apportioned sources. The results identified widespread Hg enrichment, with concentrations exceeding background levels at all sampling sites, and a Cd exceedance rate of 28.06%, leading to a moderate ecological risk level overall. Spatial patterns revealed significant heterogeneity. Quantitative source apportionment identified four primary sources: industrial source (37.1%), which was the dominant origin of Cr, Cu, and Ni, primarily associated with precision manufacturing and metallurgical activities; mixed source (26.7%) governing the distribution of Mn, As, and Hg, mainly from coal combustion and the natural geological background; traffic source (22.3%) significantly contributing to Pb and Zn; and a specific cadmium source (13.9%) potentially originating from non-ferrous metal smelting, electroplating, and agricultural activities. These findings provide a critical scientific basis for targeted pollution control and sustainable land-use management in analogous industrial cities. Full article

Traditional physical similarity simulation methods struggle to replicate the cumulative unloading–expansion effect in overburden, particularly due to inherent limitations in representing the bulking–compaction behavior of fractured rock masses in the caving zone. This significantly hinders a deeper understanding of overburden movement mechanisms. To address this technical challenge, this study innovatively proposes an experimental method designed to simulate the bulking–compaction process of rock masses in the caving zone. The method employs a composite of EPE and PP sheets. Through systematic uniaxial compression tests and orthogonal experimental design optimization, an optimal material mix ratio with superior performance was identified. Its stress–strain behavior was systematically analyzed, and its feasibility was comprehensively verified from the perspective of the synergistic evolution of displacement and stress fields. The results demonstrate that the stress–strain response of the new similar simulation material (SSM) aligns highly with the Salamon model. Furthermore, its load-bearing capacity exhibits a non-linear strengthening characteristic with increasing EPE thickness. Physical simulation validation tests, based on the engineering context of the Shilawusu Coal Mine, showed that all the relative error parameters were strictly controlled within 12%. The overall accuracy was significantly superior to existing simulation methods, achieving a substantial reduction in prediction errors for key parameters. Full article

Occupational exposure to respirable coal mine dust remains a significant health risk, especially for underground workers. Rapid dust monitoring methods are sought to support timely identification of hazards and corrective actions. Recent research has investigated how optical light microscopy (OLM) with automated image processing might meet this need. In laboratory studies, this approach has been demonstrated to classify particles into three primary classes—coal, silicates and carbonates. If the same is achievable in the field, results could support both hazard monitoring and dust source apportionment. The objective of the current study is to evaluate the performance of OLM with image processing to classify real coal mine dust particles, employing scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) as a reference method. The results highlight two possible challenges for field implementation. First, particle agglomeration can effectively yield mixed particles that are difficult to classify, so integration of a dispersion method into the dust collection or sample preparation should be considered. Second, optical differences can exist between dust particles used for classification model development (i.e., typically generated in the lab from high-purity materials) versus real mine dust, so our results demonstrate the necessity of site-specific model calibration. Full article

The mineral matter in coal has great significance for geological evolution, and clean and fractional utilization. The Laochang mining area is one of the largest anthracite coal production bases in Southern China, and the most important coal energy base in Yunnan province, China. This study investigates the composition and mode of occurrence of mineral matter in the Laochang coals to reveal the sediment provenance, sedimentary environment, and hydrothermal fluids. The predominant minerals in the Laochang coals include oxide (quartz, anatase), clay (kaolinite, illite/smectite mixed layer), sulfide (pyrite, sphalerite), phosphate (xenotime, monazite, goyazite–gorceixite), and carbonate (calcite, dolomite, sideroplesite, siderite). The minerals in the Laochang coals are dominated by quartz (2.4~54.8%) and kaolinite (3.4~39.2%), followed by illite, smectite, muscovite, calcite, pyrite, and anatase. Quartz and dolomite in SB-7+8 coal have the highest proportions, reaching 54.8% and 17.3%. The modes of occurrence of minerals reflect that the Laochang coals are affected by the epigenetic hydrothermal fluids and seawater. The chalcophile elements Hg, Pb, Se, and Cr, and lithophile elements Li, Nb, Ta, Zr, Hf, and REY are slightly enriched in XB-3 coal, which is attributed to the intrusion of seawater and the supply of terrestrial detrital materials, respectively. REY is dominated by LREY, followed by MREY, and a lower level of HREY in the Laochang coals, which have a high fractionation degree. The REY enrichment H-type is influenced by the hydrothermal fluids. Based on the relationship between Al₂O₃ and TiO₂, Al₂O₃/TiO₂ and Nb/Yb, and the negative anomaly Eu, the detrital material in the erosion source area of the Laochang coal is derived from the Emeishan Large Igneous Province basalt and felsic–intermediate rocks. Full article

In the Yangquan coal mining region, China, muffled blasting sounds commonly occur in mine surrounding rocks resulting from instantaneous energy release following the elastic deformation of overlying brittle rock layers; they are related to fracture development. Although these events rarely cause immediate hazards, their acoustic signatures contain critical information about cumulative rock damage. Currently, conventional monitoring of muffled blasting sounds and surrounding rock stability relies on microseismic systems and on-site sampling techniques. However, these methods exhibit low identification efficiency for muffled blasting events, poor real-time performance, and strong subjectivity arising from manual signal interpretation and empirical threshold setting. This article proposes retentive depthwise gated network (RDGNet). By combining retentive network sequence modeling, depthwise separable convolution, and a gated fusion mechanism, RDGNet enables multimodal feature extraction and the fusion of acoustic emission sequences and audio Mel spectrograms, supporting real-time muffled blasting sound recognition and lithology classification. Results confirm model robustness under noisy and multisource mixed-signal conditions (overall accuracy: 92.12%, area under the curve: 0.985, and Macro F1: 0.931). This work provides an efficient approach for intelligent monitoring of coal mine rock stability and can be extended to safety assessments in underground engineering, advancing the mining industry toward preventive management. Full article

Bedding angles (BAs) in coal mining promote shear failure and can trigger rockbursts. Using Particle Flow Code (PFC) direct shear simulations on coal with BA = 0°, 30°, 60°, and 90°, we quantified BA effects on mechanical behavior and cracking. Increasing BA reduces shear strength and shear modules, reaching minimum of 4 MPa and 0.7 GPa at 90°. Failure modes shift from progressive, bedding parallel shearing at 0° to mixed paths at 30–60°, and abrupt brittle failure at 90°. Crack density and orientation evolve systematically: dense bedding parallel shear at 0°; more dispersed, lower-density mixed shear tension at 30–60°; and reconcentrated, high-density cracking causing premature shear at 90°. Corresponding force chain patterns aligned at 0°, dispersed at 30–60°, and realigned at 90° govern these outcomes by modulating stress transfer across bedding interfaces. Overall, BA is the first-order control on coal shear instability; the quantified thresholds and mechanisms provide actionable guidance for excavation orientation, support design, and targeted monitoring to reduce shear out and rockburst risks in coal mines. Full article

Underground coal mines are widely distributed across China, and underground mining is highly concealed. The rapid and accurate identification of the spatial distribution of coal mining subsidence over large areas is of significant importance for the reuse of land resources in mining areas and the detection of illegal mining activities. The traditional method of monitoring subsidence basins has limitations in terms of monitoring range and timeliness. The development of synthetic aperture radar (InSAR) technology has provided a valuable tool for monitoring mining subsidence areas. However, this method faces challenges in quickly and effectively monitoring subsidence basins using wide-swath SAR images. With the rapid development of deep learning and computer vision technologies, leveraging advanced deep learning models in combination with InSAR technology has become a crucial research direction to enhance the monitoring efficiency of surface subsidence in mining areas. Therefore, this paper proposes a new method for the rapid identification of mining subsidence basins in mining areas, which integrates Deformable Detection Transformer (Deformable DETR) and InSAR technology. First, the real deformation sample set of the mining area, obtained through interference processing, is combined with simulated deformation samples generated using the dynamic probability integral method, elastic transformation, and various noise synthesis techniques to construct a mixed InSAR sample set. This mixed sample set is then used to train the Deformable DETR model and compared with common deep learning methods. The experimental results show that the monitoring accuracy is significantly improved, with the model achieving a Precision of 0.926, Recall of 0.886, F1-score of 0.905, and mean Intersection over Union (mIoU) of 0.828. The detection model was applied to monitor the dynamically updated mining subsidence in the Huainan mining area from 2023 to 2024, detecting 402 subsidence basins. Further training demonstrates that the model exhibits strong robustness. Therefore, this method reduces the construction cost of the target detection training set and holds significant application potential for monitoring geological disasters in large-scale mining areas. Full article

In Poland, the gradual reduction in hard coal mining represents a cornerstone of the energy transition and economic restructuring strategy, with all mines scheduled to close by 2049 under the Social Agreement. Given Poland’s strong reliance on coal, this process has far-reaching implications for energy security, employment, regional development, and macroeconomic stability. The aim of this study is to assess the role and scale of the hard coal mining sector’s contribution to GDP and to examine the consequences of its gradual decline for the national energy mix. In the input–output framework, a reduction in domestic hard coal supply is modelled as a shock to the output of the disaggregated hard coal sector, affecting both intermediate demand and value added through inter-industry linkages. The analysis applies an inter-industry input–output framework based on a decomposed Input–Output Table of Poland, where the aggregated “hard coal and lignite” branch was disaggregated into thermal hard coal, coking coal, and lignite. Reduction Variants (WR25%, WR50%, WR75%, and WR100%) were combined with Substitution Variant WS2, which assumes replacement of domestic hard coal with imported coal, natural gas, and electricity under varying price scenarios (−40% to +40% relative to reference levels). The Migration Variant was also included to account for labour market effects. This approach generated a set of 100 scenarios, reflecting possible pathways of Poland’s energy transition. The results demonstrate that in every scenario, reducing domestic hard coal supply leads to a decline in GDP. Losses range from −0.175% to −0.25% under WR25% scenarios to between −0.775% and −1.1% under WR100%, depending on the relative prices of imported substitutes. Substitution patterns are highly sensitive to price dynamics: under low natural gas prices, gas dominates the replacement mix (over 57% share), while under high gas prices, imported coal prevails (70–90%). Electricity imports consistently remain marginal. These outcomes highlight Poland’s structural dependence on coal, the vulnerability of GDP to external price shocks, and the limitations of substitution options. This study concludes that the reduction in domestic coal mining, though inevitable in the context of the EU climate policy, will not be economically neutral. It requires careful management of substitution pathways, diversification of the energy mix, and socio-economic support for coal regions. The input–output framework used in this research offers a robust tool for quantifying both direct and indirect effects of the coal phase-out, supporting evidence-based policy for a just and sustainable energy transition. Full article

A previous study demonstrated that spontaneous forest recovery can result in the development of functional mixed forests in post-mining areas. A critical step in this process is the establishment of climax woody species in the understory of pioneer trees. In this case study, we utilise repeated sampling to evaluate the establishment, initial survival, and growth of pedunculate oak (Quercus robur) and European beech (Fagus sylvatica) seedlings, and to newly assess Norway spruce (Picea abies) during unassisted forest recovery on a post-mining site after coal mining near Sokolov in North Bohemia. Detailed mapping of beech and oak seedlings was conducted in 2009 and 2012 (i.e., 14 and 11 years after the site was reclaimed). Now, we have resurveyed these seedlings, which has allowed us to evaluate their survival and growth. We have also mapped spruce seedlings and estimated their age from annual branch whorls. In the original study, most seedlings were found on the northern site near the edge of the post-mining area and the surrounding landscape, which serve as seed sources. Beech shows the best survival and growth on the northern site, where the greatest number of new seedlings also appear. In contrast, oaks demonstrate much higher mortality than beech overall, with the highest mortality observed on the northern site and the highest survival on the southern site, where most of the new seedlings also appeared. Interestingly, however, surviving oaks grew faster on the northern site. Across microtopography, seedlings of all three tree species were most frequent on the slopes of micro-undulations. Beech individuals were taller in depressions, whereas oaks did not consistently demonstrate a size advantage across microhabitats. Spruce colonised vigorously and was the most abundant of the three species across microhabitats. Age-frequency analyses suggest an annual mortality rate of 3%–9%. Browsing damage was observed on 19% of beech seedlings and 9% of oak seedlings. The study shows that pioneer tree stands are suitable nursing sites for studied climax tree species, which can colonise these sites several kilometres away from mature trees, and their establishment involves a complex interplay between distance to seed source and local microclimatic conditions. Our resurvey indicates that later successional stages may increasingly be shaped by shade-tolerant beech and spruce under the developing canopy. Full article

Gangue slurry pumping backfill offers a cost-effective and environmentally sound solution for coal mine solid waste disposal. Addressing the poor pumpability of pure gangue slurry, this study applied the Talbot gradation theory to a non-cemented gangue system by designing various particle size gradations and water-solid ratios (W/S). Through tests on rheological properties, slump, spread, and bleeding rate, the optimal proportion for pumpability of pure gangue slurry (PGS) within the scope of this study was determined. Tests were conducted on rheology, slump, spread flow, and bleeding rate to determine the optimal mix proportion for pumpability. The results show that: The slurry in this study demonstrates a strong correlation with the characteristics of a Bingham fluid. Its yield stress increases significantly as the W/S decreases. At a gradation index (n) of 0.4, particle packing is densest, resulting in the lowest yield stress. Slump and spread flow decrease with a lower W/S. They initially increase and then decrease as the gradation index increases, with optimal fluidity observed at n = 0.4. Bleeding rate increases with a higher gradation index but decreases with a lower W/S. Comprehensive optimization determined the optimal mix proportion as gradation index n = 0.4 and W/S of 0.18. At this ratio: Yield stress = 144.25 Pa, Slump = 255 mm, Spread flow = 60.1 cm, Bleeding rate = 2.21%. This meets the pumping requirements (Slump > 180 mm, Bleeding rate < 3%). The research results provide important experimental value for the practical pipeline transportation of PGS and the reduction in pumping friction resistance. Full article

This article evaluates the effectiveness of Poland’s current mine closure model in promoting the sustainable reuse of post-mining land, particularly in urbanised regions such as the Upper Silesian–Zagłębie Metropolis. A mixed-methods approach is applied, combining archival and cartographic analysis, field surveys, and a comparative policy review. The study examines 81 post-mining areas associated with 20 decommissioned coal mines. Two dominant transformation models are identified: planned redevelopment guided by public–private strategies, and unplanned, market-driven reuse based on opportunistic adaptation. While the system ensures technical and environmental safety via the Mine Restructuring Company (SRK S.A.), it remains weakly integrated with spatial planning policies and often marginalises key stakeholders. This leads to fragmented land reuse, underinvestment, and misalignment with sustainability objectives. A comparative review of models from Germany, the UK, and the Czech Republic highlights the importance of institutional coordination, strategic planning tools, and community involvement. The article concludes with policy recommendations to enhance governance, planning coherence, and social inclusion in post-mining transformation processes in Poland. Full article

The Bełchatów Lignite Mine (BLM) in central Poland, one of Europe’s largest Neogene lignite deposits, provides key insights into palaeofloral evolution. Located in the Kleszczów Graben, the BLM consists of four distinct lithological units: subcoal, coal, clayey-coal, and clayey-sandy units. The study presents a palynological investigation of 31 samples from all units, identifying 78 sporomorph taxa, including 10 plant spores, 15 gymnosperm pollen, and 53 angiosperm pollen taxa. Pollen grains from angiosperms and gymnosperms were consistently observed in all samples, while plant spores were scarce. The analysis reveals three distinct palynological zones, reflecting shifts in vegetation. The first zone is characterized by swamp, riparian, and mixed mesophilous forests, dominated by Taxodium/Glyptostrobus, Ulmus, Carya, Engelhardia, Pterocarya, and Quercus. In the second zone, slightly cooler climatic conditions led to the decline of Taxodium/Glyptostrobus and Alnus, indicating a deterioration of swamp forests. The third zone marks a subsequent recovery of these forests. Palaeoclimatic interpretations indicate three phases: a subtropical-humid climate during the Early Miocene, fluctuating humidity in the late Early Miocene, and a transition to a warm-temperate and humid climate in the Late Miocene. Full article

Coal seams, as critical components of open-pit mine slopes, are subjected to both quasi-static and dynamic loading disturbances during mining operations, with their mechanical properties directly influencing the slope stability. Consequently, to clarify the mechanical properties and failure mechanisms of coal seams affected by the strain rate under the static–dynamic loading conditions, the mineral composition and meso-structural characteristics of lignite were analyzed in this study, and uniaxial compression tests with different quasi-static loading rates and dynamic compression tests with different impact velocities were conducted. The results indicate that there is an obvious horizontal bedding structure in lignite, which leads to differences in mechanical response and failure mechanism at different strain rates. Under the quasi-static loading, lignite exhibits significantly lower strain-rate sensitivity than compared to dynamic impact conditions. The Poisson’s ratio difference between the bedding matrix and the lignite will produce interfacial friction, which gradually decreases with the increase in the distance from the interface, thus promoting the transformation of lignite from multi-crack tensile shear mixed fracture to single-crack splitting failure. Under the dynamic impact conditions, low-impact velocities induce stress wave reflection at bedding interfaces due to wave impedance disparity between the matrix and lignite, generating tensile strains that result in bedding-plane delamination failure; at higher velocities, incomplete energy absorption by the rock specimen leads to fragmentation failure of lignite. These findings are of great significance for the stability analysis of open-pit slopes. Full article

The depletion of shallow coal reserves necessitates a shift from open-pit to underground mining, increasing the need for safe and efficient backfill systems. However, traditional backfill materials—especially cement—are costly and environmentally burdensome. To address this, our study explores a sustainable alternative using industrial waste, contributing to the principles of a circular economy. This research presents a novel backfill formulation that achieves full cement replacement through the use of fly ash, supplemented with nanocrystalline silica and glass fiber to enhance strength and setting dynamics. Eighteen sample sets were prepared for each composition, using consistent mixing, curing, and testing protocols. Mechanical strength was evaluated at multiple curing intervals alongside microstructural characterization using SEM and XRD. The results show that mixtures containing nanomodified silica and fiber exhibit significantly improved compressive, shear, and splitting strength—up to 40% higher than fly ash-only compositions. Microstructural analysis revealed accelerated C-S-H gel development, reduced porosity, and more uniform pore structures over time. These findings confirm the mechanical viability and economic potential of waste-based backfill systems. The proposed formulation enables safer underground operations, improved extraction efficiency, and reduced environmental impact—offering a scalable solution for modern coal mining. Full article

The proportion of neutral and weakly alkaline high-sulfate mine water in China is over 50%, resulting in the problem of high treatment costs. Low-cost, sustainable, and non-secondary pollution remediation technologies for in situ application in underground coal mines have rarely been reported. Here, the mixed packed and layered packed SRB-PRB (sulfate-reducing bacteria-permeable reactive barrier) column experiments at a flow speed of 300 mL/d using low-cost corncob as a carbon source were conducted to simulate sulfate in situ remediation in goafs. The column experiments utilized the simulated weakly alkaline mine water, with an initial sulfate concentration of 1027.45 mg/L. The results showed that during the 40 d operation, the SO₄²⁻ removal kinetics included three stages: rapid reduction (0–6 d), stable reduction (6–16 d), and reduction attenuation (16–40 d). Corncob could provide a relatively long-term carbon source supply, with the maximum average removal efficiency of 65.5% for the mixed packed column and 56.6% for the layered packed column. A large number of complex organic-degrading bacteria were detected in both the effluent water samples and the solid packed media, while SRB became dominant only in the solid packed media. However, the low-abundance SRB could still maintain a high-efficiency SO₄²⁻ reduction, due to the supply of readily utilizable carbon sources provided by hydrolytic and fermentative bacteria. This indicated that the synergistic effect between SRB and these organic matter-degrading bacteria was the critical limiting factor for SO₄²⁻ removal. The microscopic characterizations of SEM-EDS (scanning electron microscopy and energy-dispersive spectroscopy) and FTIR (Fourier transform infrared spectroscopy) confirmed the damage of functional groups in corncobs and the generation of SO₄²⁻ removal products (i.e., FeS). The engineering application schemes of the SRB-PRB under both in-production and abandoned mining scenarios were proposed. Additionally, the material cost estimate results showed that the SRB-PRB could achieve in situ low-cost remediation (0.2–1.55 USD/m³) of the characteristic pollutant SO₄²⁻. These findings would benefit the engineering application of in situ microbial remediation technology for high-sulfate mine water. Full article