Search Results (13,556)

Diagenetic anomalies within the Upper Paleozoic coal-bearing strata of the Longdong area, Ordos Basin, represent a complex interplay between thermal maturation and fluid evolution, yet their governing mechanisms remain poorly understood. This study integrates petrographic analysis, X-ray diffraction, vitrinite reflectance (Ro) measurements, and fluid inclusion microthermometry to evaluate the discrepancy between organic thermal maturity and mineralogical diagenetic records. The results indicate that the mudstones achieved high thermal maturity, with mean Ro and Tmax values of 2.3% and 555.1 °C, respectively. However, the associated sandstones exhibit anomalous mineral assemblages, characterized by persistent high levels of illite/smectite (I/S) mixed-layer minerals and authigenic kaolinite, which are inconsistent with the anticipated advanced diagenetic stage. Furthermore, homogenization temperatures (Th) of fluid inclusions are significantly lower than expected, implying a localized suppression of illitization. We propose that this atypical diagenetic trajectory is governed by sluggish fluid–rock interactions in a confined diagenetic environment. Specifically, the dissolution of feldspars during acidic diagenesis provided a localized Al³⁺ supply, favoring kaolinite precipitation, while the limited availability of reactive feldspar precursors and pore-fluid retention effectively stalled the progression of illitization. These findings demonstrate that reactant availability and reaction kinetics can decouple mineralogical evolution from organic thermal maturation in coal-bearing sequences. This study provides a novel mechanistic framework for interpreting anomalous diagenetic signatures in heterogeneous sedimentary basins, offering significant implications for reservoir quality prediction in deep-seated, thermally mature strata. Full article

This study systematically examines the low-carbon transition challenges faced by the Yellow River Basin, a core strategic energy base in China with a coal-dominated energy system, under the dual carbon goals. Existing studies based on traditional econometric models or single-province analyses are mostly limited to static analysis, failing to simultaneously capture the nonlinear spatiotemporal evolution, cross-regional spillover effects, and long-term changing trends of carbon emissions in the basin. To fill this gap, this study builds an Energy–Economy–Carbon (EEC) analytical framework, and develops an integrated TFT-ASTGCN deep learning framework. Specifically, we employ the Temporal Fusion Transformer (TFT) for high-precision multivariate time-series simulation and peak forecasting, while the Attention-based Spatial–Temporal Graph Convolutional Network (ASTGCN) is used to identify complex spatial dependencies of inter-provincial emissions. The empirical results confirm that: (1) Basin carbon emissions show significant coal-driven carbon lock-in, with initial decoupling between economic growth and emissions. (2) Most provinces will maintain rising emissions under the current development mode, posing severe challenges to carbon peaking. (3) Asymmetric spatial spillover effects are prominent, underscoring cross-regional collaborative governance as a critical pathway for achieving an early and stable carbon peak in the basin. Full article

In the deep mining of metal mines, the stability of pillar–backfill composite materials (PBCMs) under cyclic loading is crucial for preventing dynamic disasters in goafs. Although previous studies have extensively investigated backfill materials under static loading, the damage evolution mechanism of PBCM under cyclic disturbance—particularly the coupled effects of pillar width and disturbance amplitude—remains insufficiently understood. To address this gap, this study explored the mechanical properties and damage evolution of PBCM under cyclic loading using an indoor testing system. Tests were conducted on composite specimens with varying pillar widths (6, 9, 12, 15 mm) and disturbance amplitudes (3, 4, 5 MPa), combined with acoustic emission (AE), digital image correlation (DIC), and scanning electron microscopy (SEM). Results show that wide-pillar specimens (≥12 mm) exhibit significantly improved bearing strength and deformation modulus, with increases of nearly 90% and over 40%, respectively, compared to narrow-pillar specimens. Notably, wide pillars maintain over 95% strength stability even under 5 MPa cyclic disturbances. Narrow pillars are prone to localized damage concentration with high-frequency AE signals and shear failure, while wide pillars exhibit uniform damage development. Failure morphology confirms that pillar size dictates failure mode: narrow pillars undergo sudden through failure, whereas wide pillars display progressive composite failure, with fewer damage-induced cavities and directional crack propagation along maximum shear stress. These findings provide a theoretical basis for stope structure optimization and dynamic disaster prevention in deep mines. Full article

Coking coal flotation is a typical nonlinear, multi-variable, and multi-objective process in which concentrate quality and combustible matter recovery must be balanced under fluctuating feed and operating conditions. To improve both predictive reliability and decision support, this study proposes an integrated data-driven framework that combines particle swarm optimization-back propagation (PSO-BP) prediction, SHapley Additive exPlanations (SHAP) based interpretation, Non-dominated Sorting Genetic Algorithm II (NSGA-II) optimization, and entropy-weighted Technique for Order Preference by Similarity to Ideal Solution (Entropy-TOPSIS) decision-making. After three-sigma outlier screening, 2000 valid distributed control system (DCS) samples were retained for model development and temporal holdout evaluation, and an additional 200 later-period industrial samples were used for independent validation. The data were partitioned chronologically, with months 1–4, month 5, and month 6 used for training, validation, and temporal holdout testing, respectively, while the months 7–8 dataset was reserved for later-period validation. The results show that PSO-BP consistently outperformed conventional BP under both temporal holdout and later-period validation. SHAP analysis identified raw coal ash and collector dosage as the dominant factors for product-quality prediction, while collector dosage and frother dosage contributed most strongly to tailing heat of combustion. NSGA-II further revealed the trade-off among clean coal ash, clean coal sulfur, and tailing heat of combustion, and Entropy-TOPSIS converted the Pareto-optimal candidate set into a practically balanced operating recommendation. Sensitivity and robustness analyses indicated acceptable stability of both the optimization process and the final decision result. Overall, the proposed framework provides an interpretable prediction–optimization–decision workflow for coking coal flotation and offers a practical basis for future DCS-assisted intelligent regulation. Full article

Semi-coking wastewater generated during coal pyrolysis contains extremely high concentrations of refractory organic pollutants, resulting in elevated chemical oxygen demand (COD) and posing significant environmental risks, making efficient COD removal a critical challenge for sustainable wastewater treatment in the coal chemical industry. In this study, a porous carbon-based resin (XDA-1G) was investigated as an adsorbent for COD removal from semi-coking wastewater. The adsorption performance and underlying mechanisms were systematically evaluated through adsorption isotherm, kinetic, and thermodynamic analyses, combined with structural characterization using FTIR, XPS, BET, XRD, and SEM–EDS. The resin exhibited a high COD removal efficiency of up to 91% with a maximum adsorption capacity of 2182 mg g⁻¹. Kinetic analysis followed the pseudo-second-order model, while the Freundlich isotherm best described the equilibrium behavior, indicating heterogeneous adsorption. Thermodynamic parameters confirmed that the adsorption process is spontaneous and endothermic. Spectroscopic and structural analyses revealed that COD removal is mainly governed by synergistic mechanisms including π–π interactions between aromatic pollutants and the carbon framework, hydrogen bonding with oxygen-containing functional groups, and pore filling within the hierarchical porous structure. These findings demonstrate the strong potential of porous carbon-based resins as efficient adsorbents for treating high-strength industrial wastewater. Full article

This study investigates the phase formation and smelting process of a complex Al-Si-Mn alloy based on thermodynamic diagram analysis (TDA). The Fe-Si-Mn-Al system was analyzed considering binary and ternary subsystems, and the standard Gibbs free energy of formation of selected ternary compounds was calculated using the additive method. Based on these results, phase equilibrium diagrams were constructed, and the system was tetrahedralized, leading to the identification of 15 thermodynamically stable tetrahedra. It was established that compositions of industrial interest are predominantly localized within tetrahedra enriched in silicide and aluminosilicide phases, particularly FeSi-Fe₂Al₂Si-Fe₃Al₁₁Si₆-Mn₅Si₃. Experimental verification was carried out in a 250 kVA ore-thermal furnace using manganese ore, high-ash coal, and quartzite. The smelting process was conducted under slag-free conditions with stable electrical operation. The obtained alloy had the following composition (wt.%): Fe ~ 12.1, Si ~ 44.7, Mn ~ 34.5, and Al ~ 5.1, with low impurity levels (C < 0.5%, S < 0.02%, p < 0.09%). Microstructural analysis using SEM-EDS confirmed the formation of silicide (FeSi, Mn₅Si₃) and aluminosilicide phases, which ensure the structural stability of the alloy. It is shown that the localization of alloy compositions within specific tetrahedra of the Fe-Si-Mn-Al system prevents self-disintegration. The results demonstrate that TDA is an effective tool for predicting phase composition and optimizing the production technology of complex ferroalloys. Full article

The coal resource-rich areas in Guizhou Province are located at the overlapping junction of the southern part of the third fold and subsidence zones of the Neocathaysian structural system and the Nanling latitudinal structural belt. These areas are characterized by well-developed folds and faults, complex coal seam structures, high in situ stress, and poor air permeability, which lead to low-efficiency conventional gas drainage and failure to achieve the expected results. In terms of enhancing coal seam permeability and improving gas drainage and utilization, research is urgently needed on the permeability enhancement mechanism of deep-hole blasting in outburst-prone coal seams under combined multi-stress action. By analyzing the influence law of coal mass fracture evolution before and after blasting, developing an experimental device for blasting permeability enhancement under combined multi-stress action, and conducting research on the pore variation law of coal mass before and after blasting, it is found that in situ stress is negatively correlated with coal mass pores, while blasting and gas stresses are positively correlated with pores. This study provides a theoretical basis and experimental evidence for permeability enhancement via deep-hole blasting in outburst-prone coal seams and further supports the selection of reasonable parameters for field tests to improve the gas drainage efficiency of outburst-prone coal seams. Full article

Gas concentration series in coal mining faces are jointly affected by multiple coupled factors, including geological conditions, mining disturbances, ventilation organization, and gas drainage intensity, and therefore exhibit pronounced nonstationarity, strong fluctuations, spatiotemporal correlations across multiple monitoring points, and occasional abrupt spikes. To address these challenges, this study proposes a gas concentration prediction and early-warning method that integrates CEEMDAN–SST with GraphPINN-TimesFM (Graph Physics-Informed Neural Network–Time Series Foundation Model). First, based on multi-source monitoring data such as wind speed, gas concentrations at multiple monitoring points, and equipment operating status, anomaly removal, operating-condition segmentation, and change-point detection are performed to construct stable operating-state labels. Feature selection is then conducted by combining optimal time-lag correlation, Shapley value contribution, and dynamic time warping. Second, WGAN-GP is employed to augment samples from minority operating conditions, while CEEMDAN–SST is used to decompose and reconstruct the target series so as to reduce the interference of nonstationary noise and enhance sequence predictability. On this basis, TimesFM is adopted as the backbone for long-sequence forecasting to capture long-term dependency features in gas concentration evolution. Furthermore, GraphPINN is introduced to embed the topological associations among monitoring points, airflow transmission delays, and convection–diffusion mechanisms into the training process, thereby enabling collaborative modeling that integrates data-driven learning with physical constraints. Finally, the predictive performance, early-warning capability, and interpretability of the proposed model are systematically evaluated through regression forecasting, warning discrimination, and Shapley-based interpretability analysis. The results demonstrate that the proposed method can effectively improve the accuracy, robustness, and physical consistency of gas concentration prediction under complex operating conditions, thereby providing a new technical pathway for gas over-limit early warning and safety regulation in coal mining faces. Full article

Deep shale of the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin represents a critical frontier for shale gas exploration in China. However, systematic understanding of the multi-scale links among lamination type, mechanical anisotropy, and fracture complexity remains limited. Based on lamination characteristics and total organic carbon (TOC) content, core samples were classified into four types. Using a multi-scale approach (uniaxial compression, Brazilian splitting, in situ CT scanning, QEMSCAN, and SEM), this study elucidates how lamination structure controls mechanical anisotropy, failure modes, and fracture mechanisms. The novelties of this work are threefold: (1) quantitatively linking specific lamination types (ORM, OPM, PAFC, PAF) to anisotropic mechanical responses; (2) introducing 3D fractal dimensions to evaluate fracture network complexity; and (3) integrating micro- (SEM) and macro-scale tests to reveal the coupled control of weak planes and brittle minerals on fracture propagation. Results indicate that laminated shales exhibit pronounced mechanical anisotropy. Loading parallel to laminations induces tensile splitting along weak planes, significantly reducing strength. Conversely, perpendicular loading generates complex fracture networks of horizontal secondary fractures along laminae and vertical main fractures through the matrix. Furthermore, 3D fractal dimension analysis quantifies fracture network complexity as follows: organic-poor clay-feldspar laminated shale > organic-poor clay-feldspar-calcareous laminated shale > organic-rich massive shale. Microscopic observations confirm that fracture propagation is jointly governed by weak plane systems and brittle mineral content, which collectively determine macroscopic failure patterns. These findings clarify how lamination type controls the laboratory mechanical response and fracture morphology of deep shale and provide a laboratory-scale framework for comparing lamination-related differences in mechanical anisotropy and fracture complexity in the Qiongzhusi Formation. Full article

Artificial dams are key retaining structures in underground coal mine reservoirs, and their mechanical performance directly affects the safety and stability of underground water storage systems. This study investigates the effects of dam type, hydraulic pressure, and top boundary condition on dam behavior using three-dimensional finite element models developed in ABAQUS. Three representative dam types, namely flat slab, gravity, and arch dams, were analyzed under three upstream water pressures (0.5, 1.0, and 1.5 MPa) and three top boundary conditions (free, simply supported, and fixed), resulting in 27 numerical cases under an overburden pressure of 4 MPa. The results show that increasing water pressure consistently increases displacement and stress in all dam types, while the deformation mode and stress redistribution strongly depend on structural form and top restraint. The flat slab dam is more prone to edge cracking and local stress concentration, the gravity dam exhibits better overall stiffness and deformation stability, and the arch dam provides more efficient stress redistribution but shows stronger edge effects under restrained conditions. Overall, the gravity and arch dams demonstrate better mechanical adaptability than the flat slab dam. These findings provide a numerical basis for dam-type selection, structural optimization, and local reinforcement design in underground coal mine reservoirs. Full article

This study aims to show a detailed life cycle assessment (LCA) approach of battery electric vehicles (BEVs) and internal combustion engine vehicles (ICEVs), with an emphasis on determining the electrical carbon intensity at which these vehicles reach life-cycle greenhouse gas (GHG) parity. The analysis was conducted in openLCA v2.0.3 using the Ecoinvent v3.9.1 database under a European use-phase context, with a functional unit of 150,000 km. BEVs were evaluated for two representative lithium-ion battery chemistries (NMC622 and LFP) under three electricity carbon intensity scenarios (50, 400, and 850 g CO₂/kWh), while ICEVs were modeled for both gasoline and diesel pathways. Results show that BEV life-cycle GHG emissions vary between 91 and 221 g CO₂-eq/km across different combinations of electricity mix, battery chemistry, and end-of-life conditions. When isolating electricity carbon intensity as the primary variable under a fixed BEV configuration, emissions increase approximately linearly with grid emission factor. Under average European electricity conditions (400 g CO₂/kWh), BEVs exhibit lower life-cycle GHG emissions than gasoline ICEVs, whereas under coal-intensive electricity conditions (850 g CO₂/kWh) this advantage may be reduced or reversed. The break-even electricity carbon intensity is derived by linear interpolation under a fixed BEV configuration (NMC622, 60 kWh, constant lifetime and EoL conditions), yielding a threshold of approximately 600 g CO₂/kWh. The results further indicate that this threshold is influenced by battery chemistry, production-related emissions, recycling efficiency, and assumed vehicle lifetime. These findings highlight the importance of simultaneous progress in electricity decarbonization and end-of-life recycling to secure the environmental benefits of vehicle electrification, and they provide a threshold-oriented framework for policy-relevant interpretation of comparative vehicle LCA results. Full article

The particle size of aggregate is a key factor affecting the mechanical properties and deformation capacity of cemented gangue filling body. In this study, coal gangue with a particle size range of (0.05, 20) mm was sieved into six groups of aggregate particles. Based on the Talbot gradation theory, cubic specimens with gradation indices n = 0.3, 0.4, 0.5, 0.6, and 0.7 were prepared for acoustic emission (AE) monitoring tests. The microstructure of the filling body was analyzed, and the failure characteristics and damage evolution laws of the cemented gangue filling body with different gradation indices were explored. The results show that the compressive strength reaches its maximum when n = 0.5. As the gradation index increases, the compressive strength of the specimens first increases and then decreases, and the specimens shift from primarily experiencing cleavage failure to shear failure. The curve of cumulative AE ringing count shows a bimodal distribution pattern, with both surge points and fracture points coexisting. The surge points can be regarded as precursor signals of backfill failure. The spatiotemporal evolution of AE events exhibits complex phased changes. An excessively small gradation index tends to form micropores and striped microcracks, reducing the compactness of the microstructure. An excessively large gradation index can lead to the formation of penetrative weak channels. A reasonable gradation index enables the mutual interlocking of aggregate particles, constructing a stable three-dimensional spatial skeleton structure. The dynamic trend of damage in the filling body can be captured based on AE analysis, and reverse guidance can be provided for parameter optimization of Talbot gradation, achieving a dynamic closed loop of “gradation design-AE monitoring-damage assessment-parameter optimization”. This not only enriches the application scenarios of acoustic emission analysis in graded materials, but also provides a new research approach and technical method for gradation design and safety assessment in scenarios where particle sizes are missing in practical engineering. Full article

To identify the sources and driving mechanisms of nitrate contamination in pore water around Nansi Lake, 54 pore water samples were analyzed via hydrogeochemical analysis, Gibbs diagrams, ionic ratios, and principal component analysis (PCA). The pore water is predominantly slightly alkaline, with dominant cations Ca²⁺ and Na⁺, and anions HCO₃⁻ and SO₄²⁻. Nitrate-nitrogen (NO₃⁻-N) concentrations range from 0.82 to 54.31 mg·L⁻¹, with a coefficient of variation of 1.41 and an exceedance rate of 18.52%, indicating significant external inputs. A positive correlation between NO₂⁻ and NO₃⁻ suggests denitrification in some areas. Nitrate concentrations exhibit distinct spatial heterogeneity: high concentrations occur in agricultural/aquaculture lakeside plains and urban areas, low concentrations near coal mining subsidence zones, and transitional zones showing outward diffusion. Nitrate sources are predominantly anthropogenic. High Cl⁻ and low NO₃⁻/Cl⁻ ratios indicate domestic and aquaculture wastewater infiltration, whereas low Cl⁻ and high NO₃⁻/Cl⁻ ratios indicate agricultural fertilizer input. Industrial and natural sources are minor. PCA identified three controlling factors (cumulative variance 69.81%): coal mining and industrial/domestic pollution (39.82%), carbonate rock weathering (19.44%), and agricultural activities (10.55%). Health risk assessment shows no significant risk for adults (hazard quotient (HQ) < 1), but children face localized risks at nine sites (HQs of 1.25–2.26) in intensive farming, urban, and transitional zones. Excessive fertilizer application and sewage leakage are the primary causes, posing methemoglobinemia risks to infants. This study provides a scientific basis for nitrate pollution control and sustainable water management in the Nansi Lake Basin and offers methodological insights for similar lacustrine plain regions. Full article

This study investigates the ternary co-pyrolysis behavior of Soma lignite (SL), sugar beet pulp (SBP), and hazelnut husk (HH) at four blending ratios (80:10:10, 60:20:20, 40:30:30, and 20:40:40 wt.%) using thermogravimetric analysis under a nitrogen atmosphere. Synergistic interactions were quantified through mass-based ($\Delta W$) and rate-based ($\mathrm{\Psi }$) deviation indices, and the contributions of individual pseudo-components were resolved by Gaussian deconvolution of DTG curves. Among the blends investigated, the 40:30:30 (SL:SBP:HH) composition exhibited the most consistent and intense synergistic effect across all temperature zones, with the strongest promotion concentrated in the high-temperature region associated with CaCO₃ mineral decomposition. Deconvolution analysis revealed that increasing the biomass fraction systematically shifted coal-related pseudo-component peaks to lower temperatures and enhanced the hemicellulose/pectin contribution, confirming that biomass-derived volatiles accelerate lignite devolatilization. These findings demonstrate that ternary co-pyrolysis of low-rank coal with two complementary agricultural by-products is a viable and sustainable strategy to enhance pyrolysis performance, valorize agro-industrial waste, and reduce the environmental footprint of lignite utilization, providing fundamental thermochemical data for the design of integrated lignite–biomass co-processing systems. Full article

Coal is inherently soft, characterized by well-developed cleat systems, low strength, and significant anisotropy. Existing models that treat coal as a continuous medium or consider only a single plane of weakness fail to capture the synergistic effects of multiple weaknesses on wellbore instability. This study addresses this gap by integrating the strength criteria of weakness planes with wellbore stress theory. First, in situ stresses were transformed into the coordinate system of the weakness planes to derive the acting stress components. A strength criterion incorporating multiple structural planes—accounting for the coal matrix, bedding, face cleats, and butt cleats—was then applied to establish a coupled wellbore stability criterion. A corresponding collapse pressure program was developed using Visual Basic to analyze the effects of stress state, wellbore trajectory, and weakness orientation. The results show that the presence of multiple weakness planes significantly increases the sensitivity of wellbore stability to trajectory. Drilling parallel to the direction of minimum horizontal stress minimizes shear stress and collapse pressure, whereas drilling at high angles or parallel to the maximum horizontal stress activates the weakness planes, leading to a sharp increase in collapse pressure. The presence of these weaknesses results in a highly non-uniform and direction-dependent collapse pressure distribution, with their synergistic interactions further exacerbating the risk of localized failure. Full article