Pre-oxidized coal (POC) presents an elevated risk of spontaneous combustion, posing a severe challenge to safety in re-mining working faces. To elucidate the effects of pre-oxidation process (POP) on the multiscale characteristics of coal spontaneous combustion, the physicochemical microstructure evolution, and heat-release characteristics of coal samples prepared at different pre-oxidation temperatures (POTs) were investigated using temperature-programmed oxidation, low-temperature N2 adsorption, Fourier transform infrared spectroscopy, and thermal analysis. The results indicated that 120 degrees C served as critical threshold for reactivity. When the POT was below 120 degrees C, moisture removal led to an increase in specific surface area and pore volume, accompanied by the accumulation of active functional groups, such as -OH and C=O, thereby significantly enhancing the re-ignition risk. The O120 sample exhibited the highest oxygen consumption and gas generation rates, along with the lowest characteristic temperatures. Conversely, when the POT exceeded 120 degrees C, the excessive depletion of aliphatic groups (-CH2-/-CH3) and thermal polycondensation induced micropore collapse and the formation of a cross-linked aromatic-ester network, which significantly impaired oxygen adsorption and diffusion. Thermodynamic analysis confirmed that the high POT samples retained a certain heat-release capacity, whereas the initial oxidation induction period was significantly prolonged, exhibiting a pronounced hysteresis effect. The results indicated that residual coal subjected to pre-oxidation at approximately 120 degrees C presented the highest risk of secondary spontaneous combustion and should be regarded as a key monitoring target for fire prevention and control in re-mining working faces.

In-situ pyrolysis is widely regarded as a promising low-carbon pathway for the utilization of tar-rich coal resources. Tar-rich coal is characterized by a high tar yield during thermal decomposition; however, its large-scale underground application is constrained by fundamental challenges associated with inefficient coal-seam heating, limited heat transfer within deep coal seams, high external energy demand, and difficulties in process control and subsurface safety management. In this study, existing research on underground in-situ coal conversion and pyrolysis technologies is systematically synthesized, with a focus on their heating mechanisms, energy supply modes, and intrinsic technical limitations. Particular attention is given to the physicochemical behavior of tar-rich coal during pyrolysis and the oxidation and spontaneous combustion characteristics of the resulting pyrolytic semi-coke. The analysis indicates that the exothermic oxidation of semi-coke can be conceptually integrated as an internal heat source, forming a coupled pyrolysis–oxidation process that enhances thermal efficiency while reducing dependence on external energy input. From a coal-seam-scale perspective, key coupling mechanisms involving heat transfer in coal-bearing porous media, combustion stability, and thermal regulation are critically examined. Based on these insights, a conceptual technical framework for controlled in-situ pyrolysis of tar-rich coal is developed, emphasizing the integration of internal heat generation, enhanced heat transfer, system sealing, and real-time subsurface monitoring. The framework further incorporates CO2 geological sequestration as a complementary pathway for emission mitigation. Overall, this conceptual framework provides a unified perspective for advancing efficient, safe, and low-carbon in-situ conversion technologies for tar-rich coal and related unconventional solid carbon resources.

Liquid fuel leakage typically forms dynamic, evolving oil spill fires rather than static, stable pool fires, posing significant hazards to both personnel safety and property assets. In this work, one-dimensional spill fire experiments were conducted on two distinct substrates (i.e., water and steel) to investigate their fire dynamics characteristics. Five typical combustion stages were consistently observed across all experimental configurations: continuous spreading, steady burning, shrinkage, quasi-steady burning, and decay stages. The analysis revealed that fires on steel substrates exhibited greater flame front propagation, larger combustion area, longer burning duration, and higher temperature rise rates compared with fires on water substrates. This discrepancy primarily stems from substrate effects on fuel layer effectiveness. When the oxygen concentration in ship engine rooms reaches 18.97–19.97

To investigate the spontaneous combustion properties of different grades of loose coal particles under stress, this study employs numerical simulation for analysis. A numerical model was established, and the experimental results were compared with the numerical predictions to verify the model's accuracy. A qualitative and quantitative evaluation of the evolution of parameters such as seepage and heat transfer characteristics, coal oxidation temperature, and oxygen consumption rate (OCR) was conducted to further elucidate the coupling mechanism between stress and particle size in coal spontaneous combustion (CSC). The findings indicate that uniaxial stressinduced fragmentation of coal particles significantly reduces porosity and permeability while simultaneously increasing thermal conductivity. Consequently, this structural evolution exerts dual effects on the coal-oxygen reaction. The grain size ratio directly influences the oxidation process by altering the coal-oxygen interfacial contact area. A higher proportion of smaller grain size coal particles correlates with increased OCR and CO generation rates, indicating a significant grain size effect in the CSC process. The coupling between stress and grain size reaches a critical point; when the stress exceeds this threshold, the oxidation-promoting effect is markedly diminished. This model elucidates the fundamental principles for assessing stress-oxidation coupling risks in deep coal seams, with important implications for developing comprehensive multi-field coupling theories related to CSC.

This study integrates macroscopic experiments and molecular dynamics simulations to investigate the synergistic use of organosilicon (GT-248) and short-chain fluorocarbon (FS-50) surfactants for coal dust suppression. The ternary system exhibits optimal wetting performance, achieving a minimum contact angle of 18 degrees and the fastest volume resistivity recovery of 7 s. Mean square displacement and diffusion coefficient analyses reveal the lowest water diffusion coefficient of 0.1716 & Aring;2/ps for the ternary system, significantly lower than those of single and binary systems, indicating enhanced water adsorption on coal dust. For agglomeration, the ternary system yields the largest average particle size of 73.18 mu m with denser structures, and the lattice contraction rate increases from 20.95% in the binary system to 21.28% in the ternary system, confirming synergistic enhancement. Wind tunnel experiments demonstrate that the optimal ternary system achieves the highest dust suppression efficiency of 91.07%, outperforming single GT-248 88.71% and binary system 90.17%. Electrostatic potential and hydrogen bond analyses reveal that FS-50 provides strong electrostatic attraction and hydration, GT-248 forms a robust hydrogen bond network, and electrolyte addition optimizes interfacial adsorption and promotes directional water migration, fundamentally improving wetting and agglomeration.

To improve dust suppression performance during coal stockpiling and transportation, this study focuses on a modified polymer system prepared by grafting acrylamide (AM) and itaconic acid (IA) onto hydroxyethyl cellulose (HEC). The effects of varying dosages of ammonium persulfate (APS) as an initiator and N,N’-methylenebisacrylamide (MBA) as a crosslinking agent on the physicochemical properties and dust suppression performance were systematically investigated in this study. The initiator and crosslinking agent jointly regulate polymerization and network formation. The optimized formulation exhibited excellent mechanical strength, wettability, and wind erosion resistance, achieving a residual mass of 98.125% after 44h of wind erosion. Molecular dynamics simulations provide deeper mechanistic insight, radial distribution function verifies molecular interactions among suppressant, water, and coal; mean square displacement reveals that moderate crosslinking under low initiator conditions facilitates water migration; and interfacial adsorption energy demonstrates that balanced crosslinking with uniform grafting strengthens interfacial bonding. An optimal initiator/crosslinking agent ratio yields a flexible yet stable crosslinked network with low adsorption energy, macroscopically translating into high dust adhesion, favourable wettability, and superior wind erosion resistance.

Thermal conductivity is a critical thermal property of coal, governing the efficiency and safety of its conversion processes. This paper presents a systematic review of the methodologies for determining coal thermal conductivity, the mechanisms of multiple influencing factors, and advances in simulation and prediction. Currently, the absence of standardized measurement protocols leads to significant variations in methods, equipment, and sample preparation across studies. Based on the principles of steady-state and transient heat transfer, this work categorizes and compares six mainstream measurement techniques, highlighting their respective applicability and limitations. The selection of an appropriate method must balance measurement accuracy, operational efficiency, and the specific characteristics of the coal material. Through a detailed analysis of the complex interplay between intrinsic coal parameters and extrinsic factors, it is elucidated that the thermal behavior of coal stems from the coupled competition between microstructural evolution and macro-environmental conditions. Furthermore, empirical and theoretical predictive models derived from experimental data are summarized, and the capability of numerical simulation techniques to reveal multi-scale heat transfer mechanisms is examined. This review addresses a notable gap in the field and offers practical guidance for selecting accurate and suitable measurement approaches for diverse coal types.

Accurate detection of surface defects on high-speed train bogies is critical to the operational safety of railway systems. Traditional supervised detection techniques face challenges in industrial environments, such as a scarcity of defect samples, high annotation costs, and complex background interference. To address these challenges, we propose a novel bogie surface defect detection system. First, high-quality images are captured using a 360° omnidirectional imaging device. We then develop an unsupervised anomaly detection method based on Reverse Distillation (RD). This method integrates a Multi-scale Information Aggregation and Fusion (MIAF) module that adaptively fuses local and global features to improve the sensitivity of small defects. In addition, the Feature-aware Bidirectional Enhancement (FABE) module employs an RD mechanism that enables the student model to learn representations of normal samples. This design is further combined with attention-guided detection to enhance the anomaly recognition performance. To enhance domain adaptability, the maximum mean discrepancy (MMD) loss is introduced to mitigate the performance degradation caused by distribution shifts between the source and target domains. Experiments on the high-speed train bogie surface defect dataset demonstrate strong performance, with an image-level AUROC of 99.7%, pixel-level AUROC of 99.5%, and defect localization overlap rate of 98.2%. Thus, the proposed method provides a reliable unsupervised framework for high-speed train bogie defect detection.

During coal storage and open-air stockpiling,photooxidation is the key precursor step triggering spontaneous combustion.However,the molecular structural regulation mechanism of the pre-oxidizing temperature on the generation of hydroxyl radicals—the core active radical species in photooxidation-is still unclear.The regulation mechanism of coal photo-oxidative hydroxyl radical generation by preoxidation temperatures ranging from 30-150 ℃ is studied through Fourier Transform Infrared Reflection,Electron Paramagnetic Resonance,hydroxyl radical trapping experiments,and mathematical analysis.It is found that the low-temperature preoxidized coal samples at 30-90 ℃ are rich in hydroxyl groups and aliphatic side chains;at high temperatures of 120-150 ℃,the aliphatic side chains fracture extensively,and aromatic structures become significantly enriched.The hydroxyl content in photooxidation exhibits exponential decay,de-termining a self-limiting rule of active site consumption and aromatic structural stability,i.e.,the reduction in oxidizable sites and the intensification of aromatization jointly inhibit the reaction driving force,essentially a restraint on the reaction process imposed by the self-reinforcing structural stability of the oxidation process itself.Pre-oxidation temperature gov-erns the stability of persistent free radicals(PFRs).Low-temperature preoxidized coal samples exhibit low aromatization levels,making PFRs prone to react and consume with aliphatic side chains,with less stability,whereas high-temperature is the opposite.Under the light,the hydroxyl radical spin density is positively correlated with the pre-oxidation temperat-ure:the hydroxyl radical spin density in high-temperature coal samples reaches 108-109 mm-3,with a response time of 10 min;the hydroxyl radical spin density in low-temperature coal samples is below 108 mm-3,requiring 20 min for response.Mechanistic analysis indicates that high temperature enhances hydroxyl radical generation through two pathways:one is to promote the aromatization to stabilize the electronic environment of PFRs,reducing non-specific inactivation;the other is to push for aliphatic hydrocarbon fracture to increase active sites,enhancing the transformation from photo-induced PFRs to hydroxyl radicals.Although low-temperature coal has many initial active sites,the instability of PFRs limits conversion efficiency.A mechanism chain linking"pre-oxidation temperature-molecular structure-PFRs stability-hydroxyl radical generation"is further established,clarifying the interrelationship among temperature regulation,structural evolution,and radical active species.These research outcomes refine the multiscale correlation theory of spontaneous combustion caused by coal photooxidation,providing critical theoretical support for preventing and controlling spontaneous combustion in stored and open-air coal.

Oxidized coal in the oxygen-poor environment of goaf is prone to reignite. This jeopardizes the production safety of coal mines. Therefore, in order to simulate this process, the coal is heated to 60, 90, 120, 150℃ through the thermogravimetric (TG) and differential scanning calorimeter (DSC) and continuously injected with oxygen concentration of 5

To enhance the flame retardancy and smoke suppression performance of silicone rubber foam (SRF), an efficient and environmentally friendly flame-retardant and smoke-suppression system was developed by incorporating aluminum hydroxide (Al(OH) 3 ) and carbon molecular sieve (CMS). Al(OH) 3 /CMS/SRF composites were fabricated via physical blending, and their flame retardancy, smoke suppression performance, and associated mechanisms were systematically investigated. Results indicate that at mass fractions of 5 wt% and 2 wt% for Al(OH) 3 and CMS, respectively, the composite achieves a limiting oxygen index of 30.8% and attains a UL-94 V-0 rating. Compared with pure SRF, the composite exhibits reductions by 21.41%, 51.8%, 70.3%, and 93.9% in peak heat release rate, total heat release, smoke production rate, and total smoke production, respectively, demonstrating excellent flame retardancy and smoke suppression performance at this optimal loading. Mechanistic analysis reveals that CMS provides a physical supporting skeleton and synergistically forms a dense SiO 2 /char barrier layer with Al 2 O 3 , which effectively prolongs the ignition time and impedes heat and oxygen transfer. This design offers a green, highly efficient synergistic flame-retardant and smoke-suppression strategy, showing great potential for application in silicone rubber foams.

Coal dust explosion and respirable dust hazards remain critical challenges in underground coal mining. In this study, a multifunctional dust suppression and explosion mitigation system was developed by integrating an organosilicone surfactant (GT-248), a short-chain fluorocarbon surfactant (FS-50), and sodium chloride (NaCl). The synergistic effects of the composite system on coal dust wettability, agglomeration, dust suppression, explosion characteristics, and thermal stability were systematically investigated through experiments and molecular simulations. The optimized GT-248/FS-50/NaCl system significantly improved coal dust wettability and particle aggregation by enhancing interfacial interactions and promoting the formation of stable liquid-bridge structures. The dust suppression efficiency reached 91.07% under optimal conditions. Moreover, the composite system effectively reduced explosion sensitivity and severity by increasing the minimum ignition temperature from 465 to 590 °C, increasing the minimum ignition energy from 70 to 338 mJ, increasing the minimum explosible concentration from 44 to 52g·m⁻³, and decreasing the maximum explosion pressure from 0.656 to 0.621MPa. Molecular dynamics simulations revealed that enhanced interfacial adsorption, restricted water molecular mobility, and strengthened hydrogen-bond networks contributed to improved wetting and thermal stability. This study provides new insights into the molecular mechanism of multifunctional coal dust suppression and explosion mitigation system.

The heat transfer behavior of hydrogen-enriched natural gas (HENG) jet flames impinging on a vertical wall was systematically investigated to clarify the effects of key parameters on wall heat flux distribution. Experiments were performed using nozzle diameters of 3 similar to 5 mm, hydrogen volume fractions of 0-30%, and impingement distances of 10 similar to 50 cm. Spatial distributions of total, convective, and radiative heat fluxes on the wall were measured, and a dimensionless heat flux model was developed based on the Reynolds number and the free flame length. Results indicate that convective heat transfer dominates wall heating, while the radiative contribution remains limited. As the impingement distance increases from 10 cm to approximately 30 cm, enhanced entrainment and recirculation lead to longer residence of high-temperature gases near the wall and a marked increase in total heat flux; beyond 30 cm, the recirculation weakens and the heat flux declines gradually. With increasing hydrogen enrichment, the combustion intensity rises, the wall-attached flame region broadens, and convective heat transfer is strengthened, yielding higher total wall heat flux. Larger nozzle diameters (3 similar to 5 mm) promote stronger entrainment and recirculation, extending the residence time of hot gases and further enhancing convective transfer. The proposed dimensionless model accurately predicts the mean heat flux across different conditions, achieving a correlation coefficient of R-2 >= 0.91. These findings provide an experimental and theoretical basis for the structural optimization and thermal safety design of hydrogen-enriched natural gas combustion systems.

To reveal the explosion risks of gases during the pyrolysis of bituminous coal, this study focuses on the bituminous coal from Linfen, Shanxi, China. It investigates the effects of different sample scales and heating rates (0.5–2 °C/min) on the gas generation pattern during pyrolysis. Based on the evolution ranges of major gas components over the temperature interval of 400–600 °C, twelve representative gas compositions were extracted using an extreme-value screening method to define the explosion risk boundaries. Subsequently, their explosion characteristics were measured using a 20 L spherical explosion test system under various equivalence ratios (φ = 0.8, 1.0, and 1.2) and initial temperatures (20–100 °C). Results show that the gas generation pattern exhibits clear stages: a low-temperature degassing stage characterized by the release of CO and CO2; a medium-temperature depolymerization stage marked by the concentrated release of C2–C3 heavy hydrocarbons; and a high-temperature polycondensation stage with a sharp increase in H2 content. Regarding explosion characteristics, the maximum explosion pressure Pmax (MPa), the maximum rate of pressure rise (dP/dt)max (MPa/s), and the deflagration index KG (MPa·m/s) all peak at the stoichiometric ratio, with explosion pressures generally higher under fuel-rich conditions than under fuel-lean conditions. Notably, the highest value of explosion severity (KG) does not correspond to the case with the highest hydrogen content (Case 11, H2 content 49.45%), but rather to the case with the lowest carbon dioxide content (Case 8, CO2 content 3.00%), indicating that the dilution effect of CO2 on explosion suppression is more significant than the promoting effect of H2. When the initial temperature rises from 20 °C to 100 °C, Pmax decreases linearly due to reduced gas density, but (dP/dt)max remains essentially constant or slightly decreases. This study clarifies the gas generation pattern and explosion characteristics of bituminous coal pyrolysis gases, providing an experimental basis for engineering safety design and risk assessment of this technology.

Coal spontaneous combustion (CSC) involves overlapping parallel reactions, where the competitive intensity determines the oxidation pathways and reaction rates. To elucidate the competitive interactions among parallel reactions, the oxidative reaction mechanisms and kinetic processes of long-flame coal (CYM), gas coal (QM), and coking coal (JM) below 700 degrees C were analyzed using thermogravimetry, infrared spectroscopy, and temperatureprogrammed experiments. The results demonstrate that the process of CSC comprises five competitive reactions: dehydration and desorption, oxygen adsorption, oxidative decomposition, gas-phase combustion, and solidphase combustion. The competition intensity of reactions governs the dominant pathways, resulting in differential variations in gas concentrations, functional groups, and mass loss rates. The oxidative reaction dominated 41-53 % of the temperature range post moisture and gas release, with rapid O2 consumption and ether bond absorbance peaking. Beyond 425 degrees C, gas-phase combustion dominated with 36-43 % mass loss contribution, accompanied by an increase in CH4. High-temperature conditions shift the dominant reaction to solid-phase combustion. Modified KAS kinetics showed decreasing activation energy for oxidative decomposition and gasphase combustion in CYM/QM with conversion but increasing energy in JM. Oxidative decomposition promoted gas-phase combustion, narrowing its activation energy range, while gas-phase combustion inhibited solidphase reactions. This provides a theoretical basis for targeted suppression.

In the process of underground metal mining, the use of traditional upward fan-shaped holes is limited by rock drilling quality, low blasthole utilisation rate and inefficient mining. According to the conditions at the Gongchangling iron ore deposit, a large-span parallel-hole ore-dropping technology was adopted. The main feature of this technology was to increase the width of the mining roadway. To study ore migration caused by long-span parallel-hole blasting in the Gongchangling iron mine, a discrete element software package, PFC2D, was used to numerically calculate the effects of parallel-hole blasting with three spans and three hole spacings to complete the calibration of the parameters of microscopic particles. Research findings indicate that: First, following parallel-hole blasting, the loose body poured into the mining roadway, the displacement in the middle was large, and the displacement on both sides of the body was small; second, the influences of two factors, the span of the mining roadway and the blasthole spacing, on the contact characteristics of the particles were analysed; third, the blasting force chain of parallel holes with different hole spacings and spans showed anisotropy, with the contact force slightly larger in the vertical direction than the horizontal direction.

This paper investigated the macroscopic phenomena and internal mechanism of short-chain fluorocarbon surfactants on different metamorphic coal dust via experimental and molecular dynamic simulation approaches. The results demonstrate that lignite, compared to anthracite, possesses a lower degree of metamorphism and higher oxygen content, making it more effectively treated by short-chain fluorocarbon surfactants with a maximum dust suppression efficiency of 92.47 %. The best immersing time, contact angle and droplet penetration time for lignite are 18 s, 20.15 degrees and 1.20 s respectively, illustrating significantly better wetting behaviour compared to anthracite. The aggregation performance of lignite is reflected in the largest particle size distribution and average particle size, which are 440-497 mu m and 83.79 mu m, respectively, and the surface roughness of lignite particles is more prominent than that of anthracite. The simulation results show that lignite performs lower negative potential values and larger electrostatic potential energies (EPE) compared to anthracite, leading to lignite attracting more water molecules. More hydrogen bond numbers and higher hydrogen bond energies indicate that lignite molecules exhibit a stronger ability to aggregate water molecules, demonstrating robust performance in both wetting and agglomeration. The diagonal term energy, cross-term energy, non-bond energy, and potential energy indicate that lignite molecules exhibit stronger intermolecular forces with water molecules, resulting in greater system stability. Furthermore, the results of interfacial adsorption energy reveal that the adsorption force of the lignite system on water molecules is stronger than that of the anthracite system.

In cold-region open-pit mine slopes, damage accumulation and mechanical deterioration induced by in situ stress and seasonal freeze–thaw alternation can easily trigger sudden instability. To investigate the effects of temperature difference under coupled constant loading and freeze–thaw action on the mechanical response and failure precursors of rock, based on the self-developed TCDR-I temperature–stress coupled testing system, uniaxial compression tests and real-time acoustic emission monitoring were conducted on water-saturated sandstone under a constant load of 1.4 MPa and multiple freeze–thaw temperature gradients. The mechanical behavior of freeze–thawed water-saturated sandstone and the acoustic emission characteristics during failure were analyzed. Combined with critical slowing down theory, the failure precursor characteristics of water-saturated sandstone under freeze–thaw action were investigated, and the internal mechanism of damage accumulation and defect evolution under the coupled effects of constant load and freeze–thaw temperature difference was revealed. The results show that, with increasing freeze–thaw temperature difference, the number of cracks and crack ratio in the loaded water-saturated sandstone gradually increased, whereas the compressive strength, elastic modulus, and total strain energy gradually decreased. After freeze–thaw treatment at −40 to 20 °C, the compressive strength, elastic modulus, and total strain energy decreased by 19.24%, 13.72%, and 44.77%, respectively, compared with those of the unfrozen–thawed specimens. During specimen failure, the dominant crack type gradually shifted from shear cracking to tensile cracking. The acoustic emission b-value and precursor points identified from multiparameter variance can both be used as criteria for predicting specimen failure. The warning lead time increased with increasing freeze–thaw temperature difference. After freeze–thaw treatment at −40 to 20 °C, the predicted failure times based on these two indicators preceded the actual failure time by 11.05 s and 16.19 s, respectively. The findings provide a theoretical basis for the early warning of sudden disasters in rock masses in cold-region engineering.

Cambrian and Ordovician carbonate aquifers are widely distributed in North China,characterized by abundant water,high water temperatures,and easy reinjection.It is a preferred choice for the development and utilization of middle and deep geothermal resources in China.Previous research has primarily focused on the permeability,water abundance,and hydrochemical characteristics of Cambrian and Ordovician aquifers,however,the genesis of their geothermal water remains unclear,which limits the evaluation and development of these geothermal water resources.By testing and analyz-ing the primary ions and environmental isotopes(34SSO4,18OH2o,2HH2O,13CDIC,14CDIC)of 32 surface hydrological bore-holes and underground water outlets in this area,the hydrogeochemical and geothermal characteristics of Cambrian and Ordovician karst groundwater in Huainan Coalfield on southern edge of North China were explored and revealed.The res-ults show that:the carbonate outcrop area in the southern part of Huainan Coalfield is a groundwater recharge area with low water temperature(18.1-23.2 ℃),low TDS(0.28-0.49 g/L),hydrochemical type of HCO3-Ca;The underground wa-ter runoff and discharge area in the central concealed zone has high water temperature(30.6-50.7 ℃),high TDS(1.93-3.06 g/L),a hydrochemical type of Cl-Na.The formation process of geothermal water in the central part of the re-search area is mainly dominated by the dissolution of evaporite rocks(rock salt and gypsum,hard gypsum)and cation ex-change,followed by the combined effects of carbonate dissolution,dedolomitization,and microbial activity.The geo-thermal water in the study area mainly comes from the infiltration and recharge of ancient atmospheric precipitation,with a corrected age of 31 080 to 36 830 years(average is 34 140 years),corresponding to Late Pleistocene.The silica temper-ature scale shows that the temperature of karst thermal reservoirs in the area is 59.8-80.1 ℃(average is 68.1 ℃),and the circulation depth of geothermal water is 1 559.7-2 273.8 m(average is 1 851.8 m).Based on the above research results,a conceptual model for the evolution of the geothermal water cycle in Cambrian and Ordovician carbonate aquifer of Huain-an Coalfield was established.Driven by terrain and gravity,atmospheric precipitation in the southern outcrop area infilt-rates downwards through channels such as fractures and faults.It continuously heats up deep underground to form geo-thermal water.During this process,groundwater interacts with carbonate rocks containing evaporite minerals,resulting in high-sodium and high-sulfate geothermal water,which ultimately discharges outward through overflow,underground drilling,and water outlet points.

Gas leak monitoring represents a critical component in the production, transportation, and processing of highsulfur natural gas, playing a vital role in ensuring operational safety across all stages and enabling environmental impact assessment following potential leaks. This study addresses spectral interference challenges in midinfrared laser gas monitoring systems by developing a gas concentration inversion model based on a mixedLorentzian approach. Focusing on the two primary constituents of high-sulfur natural gas - methane (CH4) and hydrogen sulfide (H2S) - we established an 8.309 mu m central spectral line suitable for simultaneous detection of both gases and implemented a remote mid-infrared laser system.To resolve signal interference between CH4 and H2S during mixed-gas monitoring, we employed spectral line broadening techniques under simulated high-sulfur gas leakage conditions. This enabled effective deployment of the mixed-Lorentzian model for gas signal separation. The parameters derived from the separated Lorentzian components were subsequently integrated into our concentration inversion model, achieving successful decomposition of mixed infrared laser signals.System stability evaluations demonstrated that our mixed-Lorentzian separation model effectively resolves composite gas signals while preserving absorption feature integrity. The model achieved correlation coefficients of 0.9541 for CH4 and 0.9591 for H2S, both exceeding the 0.95 threshold. These results confirm the method's accuracy in simultaneous monitoring of CH4 and H2S concentrations within high-sulfur natural gas environments. This methodology shows significant potential for extension to similar challenges across the energy sector.