Coal Mine Research Articles

Determination of Optimal Fleet Equipment to Mitigate Greenhouse Gas Emissions in an Open Pit Coal Mine

Determination of Optimal Fleet Equipment to Mitigate Greenhouse Gas Emissions in an Open Pit Coal Mine

An analytical solution for critical sliding surface of stepped rock slope: a case study of Xinjing coal mine landslide

An analytical solution for critical sliding surface of stepped rock slope: a case study of Xinjing coal mine landslide

Application of modified solidified soil in in-situ backfilling of coal gangue: evaluation of arsenic stabilization effect and mechanism study.

As a typical ecologically fragile area, the Wudong Coal Mine region in Xinjiang generates large accumulations of coal gangue each year, which, in the alkaline soil environment, can easily lead to significant leaching and accumulation of As. This study developed a stabilizer (CFD) using cement, fly ash, and desulfurized gypsum to modify in-situ soil in the Xinjiang mining area, resulting in a modified solidified soil with excellent geotechnical performance and As stabilization capability. The study results showed that when CFD content exceeded 14.5% (H8), the unconfined compressive strength was above 350kPa. The adsorption capacity of the solidified soil for As could exceed 90%. Leaching experiments revealed that the As leaching amount from solidified soil-coal gangue was below 0.01mg/L, meeting China's Class III groundwater standard, thereby effectively reducing ecological and environmental risks. The modified solidified soil prepared in this study expanded the application scenarios for cement, providing a technical basis for the large-scale in-situ disposal of coal gangue in Xinjiang mining areas. It reduced the disposal costs of coal gangue and offered insights into its resource utilization and harmless use.

Study on the safety distance determination model for natural gas wells in Ordos Basin subsidence areas of coal mining

To optimize the safe distance between coal mining faces and natural gas wells, with the Ordos Basin as the engineering background for the intersectional development of natural gas and coal resources, a Gaussian function equation for subsidence curves under complete mining was proposed based on the probability integral method, and a model was constructed to determine the coordinated mining safety distance between coal mining faces and natural gas wells. Based on the distributed optical fiber monitoring principle of the BOTDR technology, on-site monitoring of the simulated monitoring well GX1 within the safety distance was carried out. The results indicated that the maximum strain change values of the outer casing and inner production casing of the simulated monitoring well GX1 were 836 με and 766 με, respectively, far less than the maximum ultimate tensile strain value of the overlying rock at the same depth position. Furthermore, the casing structure possessed ample resistance capability, ensuring no noticeable deformation occurred. Through comparison, it was found that the discriminant model reduced the reserved safety distance between the coal mining working face and the natural gas well by 58% compared with the currently used avoidance method of the surface subsidence boundary, liberated coal resources, and achieved a "win–win" situation of the coordinated mining of natural gas resources and coal resources. It can reasonably adjust the coordinated mining problem without a natural gas-coal co-mining mechanism, provide a new method for the layout of natural gas wells in gas-coal overlapping areas, and provide new ideas for the coordinated mining of coal-related associated resources.

Comparative analysis of certified emission reduction methodologies for methane emission reduction in China.

As one of the top emitters of methane (CH4), China must take action to achieve its carbon neutrality goal. Programs to reduce CH4 emissions would benefit from the establishment of the China Certified Emission Reduction (CCER) trading market. However, studies investigating the impact of the CCER trading market on CH4 reduction remain limited. This study therefore analyzes the emission reduction performance of CH4-related CCER projects and investigates their accounting methodologies. The results show that 182 CH4 emissions reduction projects were registered between 2012 and 2017, covering coal mining, energy, waste treatment and disposal, and agriculture, with an annual emissions reduction of 19.8 MtCO2e. It was observed that, while the pre-restart methodology system covered a wide range of emission reduction areas, its application frequency was unevenly distributed. Most projects were registered in only a few emission reduction domains, with the majority of methodologies remaining unused since their publication. Moreover, the IPCC default values were frequently used in China-specific emission accounting, leading to significant uncertainties. Recommendations are made on how to improve the effectiveness of CH4 emissions reduction measures based on this analysis.

Spatial Distribution and its Driving Forces Analysis of Soil Heavy Metals in Semi-Arid Grassland Surface Coal Mining Areas

Spatial Distribution and its Driving Forces Analysis of Soil Heavy Metals in Semi-Arid Grassland Surface Coal Mining Areas

Understanding the influence of stratification for mine water management: a comparative study

Managing mine water in the best possible way is of great importance and depends on various factors like environmental protection, regulatory compliance and human health. To understand the complex chemical and hydrodynamic processes within the mine pool, it is critical to establish effective practices and management strategies. This study focuses on the characterisation of hydrodynamic processes affecting flooded underground mines, emphasising the importance of density stratification. The investigation of 29 ore and coal mine shafts and their corresponding physico-chemical depth profile measurements was aimed to compare the profiles with each other, while also taking into account the shaft geometry and the layout of the mine. Finding cross-links between the profiles, which allow universal statements on stratification in flooded underground mines, was the main objective. Results of this study indicate that stratification occurs in almost all flooded underground mines, and the uppermost stratified water body is usually located in the area of the first or second connected level. Furthermore, stratification is often responsible for considerably better quality of the uppermost water body. Hence, stratification is fundamental to mine water management and has a direct influence on the quality of the discharged water. This knowledge is invaluable in developing strategies to optimise mine closure, mine water management, treatment planning and future mine layouts.

The Mechanisms Controlling the Characteristics of Groundwater in the Qinan Coal Mine

The Mechanisms Controlling the Characteristics of Groundwater in the Qinan Coal Mine

Using roof borehole electrical resistivity tomography to monitor roof water infiltration in a mine work face

Roof water inrush in coal mining is a significant type of water-related disaster that usually results from the interconnection of water-bearing geological formations formed by cracks during and after work face mining. Therefore, monitoring roof water infiltration is of paramount importance in preventing or mitigating water inrush in the mine work face. This study employed the roof borehole electrical resistivity tomography method to conduct physical experiments for monitoring water seepage in roof cracks generated during coal model mining. Additionally, roof water infiltration monitoring was performed in the 7130 work face of the Qidong Coal Mine. The results of both physical experiments and field tests demonstrate that roof borehole electrical resistivity tomography (ERT) is well suited for monitoring roof water infiltration in mine work faces, enabling the determination of the temporal and spatial distributions of water seepage. By analyzing the variation patterns of low-resistivity anomalies in the resistivity profile, the water-conducting channels and water outflow points can be identified. Experiments and field tests suggest that the resistivity and its changes are related to the amount of water inflow and water channel. With the increase of water inflow, the relatively low resistivity anomalies region increases, the resistivity value decreases and the water channel appears and expands. With the amount of water inflow decreasing, the relatively low resistivity area becomes smaller, the resistivity value increases, and the water channel narrows or even disappears.Furthermore, by combining the areas of low-resistivity anomalies, a qualitative assessment of the water content can be achieved. Finally, The results of the periodic weighting analysis of the field tests indicate that roof water infiltration is related to periodic weighting. The greater the periodic weighting is, the more severe the roof water infiltration.

Sustainable application of waste gangue mortar in coal mine tunnel support

With the increase in coal mining depths, soft and fractured roadway surrounding rocks require grouting and a sprayed protective layer for maintenance. Simultaneously, extensive accumulation of coal gangue causes diverse environmental issues. To enhance on-site coal gangue utilization, this study replaced river sand and cement with coal gangue to develop a novel cement-based mortar for supporting coal mine roadways. The study examined how apparent density, compressive strength, flexural strength, and fiber reinforcement affect performance, while investigating the hydration reaction mechanism. The results show that compared with ordinary mortar, the apparent density and compressive strength of coal gangue-basalt fiber cementitious mortar are reduced, but its flexural strength is improved. Furthermore, a constitutive model for coal gangue-basalt fiber cement-based mortar under compression was formulated. The model comprehensively assessed the compressive strength of specimens and determined correlation coefficients for the rising and falling sections of the stress-strain curve. Micro-aggregates enhance the internal skeleton density in coal gangue-basalt fiber cement-based mortar.

Numerical investigation of coal pillar damage mechanisms for various width-to-height ratios

Pillar stability has garnered significant attention owing to the effects of pillars on coal resource recovery rate, coal pillar stability, and coal bump risk. This study examined the roadway stability control principles of conventional and yield coal pillars. The conventional coal pillars were designed as load-bearing structures with a high load-bearing capacity to carry most of the abutment load, while yield coal pillars were designed as buffer structures for transferring rapidly increasing abutment loads to adjacent solid coal ribs by progressive deformation. In order to analyze the features of dynamical evolution of vertical stress distribution and failure zone during loading, a meticulously validated roof–coal–floor composite mathematical model was established.The energy evolution for coal pillars under diverse w/h ratios was analyzed, and the failure energy ratio and elastic strain energy release rate were introduced to evaluate the failure severity. Furthermore, the behavior and damage mechanism differences between conventional and yield coal pillars were investigated: conventional pillars are designed as strong structures that bear most of the load while the yield pillars are designed to buffer and transfer sudden loads to nearby solid coal ribs by gradually deforming. Finally, two case studies of conventional coal pillars in the Zhulinshan coal mine and the yield coal pillars in the Tashan coal mine were reported.

Research on the infiltration law and enhancing application of dust suppressants in powder materials

ABSTRACT Dust emissions from open-pit mining pose a significant threat to environmental safety and human health. Currently, the range of dust suppressants used in coal mining is limited, often failing to account for their suitability across various stockpiles. This oversight results in poor infiltration after application, leading to insufficient crust formation and reduced durability. To explore the permeability of dust suppressant solutions in different stockpiles and develop a broader range of suppressants, numerical simulations were conducted to analyze the effects of liquid properties on infiltration rates. The results showed that increased liquid surface tension promotes infiltration, whereas higher solid-liquid contact angles and liquid viscosity inhibit it. Building on these findings, experimental work was undertaken using a water-based polyurethane with strong adhesion and low viscosity, combined with xanthan gum and polyethylene glycol, to optimize the dust suppressant formulation. The optimal binder formulation was found to contain 1.5% water-based polyurethane, 0.2% xanthan gum, and 1% polyethylene glycol. Infiltration experiments revealed distinct infiltration patterns for the dust suppressant solution in both rock and coal dust. The appropriate dosage of surfactants was also determined. The study indicated that surfactants enhance wettability and significantly reduce the solution’s surface tension. For hydrophilic rock dust, moderate surfactant addition improves permeability, while excessive amounts disrupt capillary forces. In contrast, for hydrophobic coal dust, wettability governs infiltration, with surfactants enhancing this property. Based on these findings, dust suppressant solutions suitable for both rock and coal dust were formulated. The formulations demonstrated excellent permeability, consolidation effects, and water resistance, as validated by tests measuring wind erosion resistance, crust strength, and water erosion resistance. The significance of this research lies in its comprehensive exploration of dust suppressant efficacy within different particulate media and the factors influencing penetration performance, providing important guidance for industrial and environmental management. With the rapid pace of industrialization, dust generation poses a serious threat to both the environment and human health, making the development of effective dust suppressants increasingly critical. This study employs numerical simulations and experimental investigations to reveal the impact of various solution properties on penetration performance, particularly highlighting the application of a novel aqueous polyurethane binder, which demonstrates strong adhesive properties and low viscosity. Through optimization of the binder composition via orthogonal experiments, the research identifies optimal surfactant concentrations tailored for rock and coal dust, thereby enhancing the penetration and binding capabilities of the suppressants. This finding not only improves the performance of dust suppressants but also provides a scientific basis for practical applications, effectively reducing dust dispersion, improving air quality, and protecting the ecological environment. Furthermore, the study validates the effectiveness and durability of the developed suppressants through wind erosion resistance, crust strength testing, and water erosion experiments. This research offers practical solutions for the mining, construction, and related industries in controlling dust, while also providing reliable scientific support for policymakers in environmental protection. In summary, this study not only holds significant academic value but also offers actionable guidance for dust control and environmental conservation in real-world applications.

Failure and development height of overlying rock of a water flowing fracture in goaf under a karst aquifer

The factors leading to mine water inrush accidents are mainly sources of water, water channels, and intensity of water inrush. Mine water rush depends mostly on whether damage leads to the overlying strata of the working face penetrating the overlying aquifer. There is therefore a need to characterize how the overlying strata of the coal seam roof fails and the development height of the water-conducting fracture zone during a roof water inrush incident. This study focuses on the Longfeng Coal Mine, northern Guizhou coalfield. Samples of rock from the roof coal seam were obtained by drilling and coring and examined under a scanning electron microscope. The results showed an undeveloped state of primary cracks in the overlying strata of the coal seam roof, with the water channel occurring mainly along mining-induced cracks. Four key strata were identified, and their fracture steps were calculated through integrating the results of the physical test of the overlying rock of the coal seam. The key strata break when the advancing distance of the working face exceeds their fracture steps. At this point, water-conducting cracks develop upwards. Simulation by FLAC3D allowed the analysis of vertical displacement, vertical stress, and evolution of the plastic zone of the roof overburden rock under different working face advancing distances. The results show that the changes in vertical stress and displacement in overburden rock initially increased rapidly, with this rate of increase subsequently slowing. The shape and maximum height of the plastic failure zone was typical trapezoid and 46.12 m, respectively. Finally, the height of the water-conducting fracture zone determined on site was 42–51.8 m. The good agreement between numerical simulation and measurements confirms that the results of this study can guide practical engineering.

Intelligent Gas Risk Assessment and Report Generation for Coal Mines: An Innovative Framework Based on GLM Fine-Tuning

Intelligent Gas Risk Assessment and Report Generation for Coal Mines: An Innovative Framework Based on GLM Fine-Tuning

Preparation of CuO–CeO2/CaO Composite Oxides and its Ablation Performances of CO/CO2

ABSTRACT CuO – CeO2/CaO composite oxide was prepared for mine special environment in this study through the solid-phase impregnation method using the traditional CuO – CeO2 and CaO as the CO catalyst and the modified additive, respectively, to address the CO poisoning in underground coal mines effectively. Influences of CaO mass on the ablation performances of CuO – CeO2/CaO were investigated under dynamic and static CO/CO2 heat capture experiments using the self-made activity testing device. Results demonstrated that adding CaO can realize in-situ adsorption of CO2, thus increasing utilization of oxygen and promoting CO catalysis of the prepared composite oxide. The performances of CuO – CeO2/0.15CaO was the best when the dosage of CaO was 15 wt%. The CO reaction capacity and CO2 adsorption capacity reached 1.17 and 0.56 mg·g−1, respectively. The thermodynamic properties and microstructural characteristics of the synthesized composite oxide were systematically investigated utilizing a simultaneous thermal analyzer, Fourier infrared spectrometer, XRD diffractometer, and scanning electron microscope. Adding CaO can also improve the thermostability of the composite oxide and increase active sites on the sample surface. The emergence of adsorption products Ca(OH)2 and CaCO3 proves that CuO – CeO2/CaO has relatively good moisture and CO2 adsorption. Analysis of the ablation performances of CO/CO2 after coal combustion with CuO – CeO2/CaO revealed that the prepared composite oxide not only effectively lowers CO concentration after coal combustion but also adsorbs CO2 during catalysis and decreases smoke risks. The released CO concentration from coal combustion after 240 s can be decreased to less than 0.0024% when the mass ratio of CuO – CeO2/0.15CaO and coal is 1:3. The ablation results confirm that, as a new type of composite material, the CuO – CeO2/0.15CaO composite oxide can provide a new technical means for CO control in coal mines.

Hydrological and hydraulic drivers of microplastics in a rural river sourced from the UK's largest opencast coal mine.

Microplastics (MPs) are ubiquitous in river and freshwater ecosystems. However, the hydraulic and hydrological mechanisms that regulate the activation and emissions of MPs from both the land surface and subsurface into rivers are not well understood. This study aims to quantify the instream MP concentration and MP load in a remote headwater catchment river (Taff Bargoed, Wales, UK), which drains the UK's largest opencast coal mine (Ffos-y-fran), over a two-year period. Small fibers (< 1mm) composed of acrylic and polyester dominated the MPs found in the Taff Bargoed, while less commonly observed MP fragments were mostly composed of polysulfone. River MP concentrations ranged from 0.27 to 28.87MP/m³ (average: 14.60±10.31MP/m³), and MP load ranged one order of magnitude from 0.08 to 3.04MP/s (average: 1.42±0.81MP/s). Statistically significant relationships were found between MP concentration, the number of dry weather hours and river discharge, which indicated rainfall-runoff induced, source limited, dilution effects on instream MP concentration. A negligible relationship between MP load and river discharge was observed, which suggests that MP load variability was independent of flow conditions, dry weather hours, and the MP concentration in the Taff Bargoed. Significant positive relationships between MP concentration and instream total suspended solids were also observed, indicating that this may provide a useful proxy for estimating MP variation in the Taff Bargoed. No longitudinal variation in MP concentration over a 2km reach was observed, where differences in flow and drainage area were negligible, however, MP concentration increased by a factor of 2-4 downstream of an inflowing tributary, also sourced from the Ffos-y-fran coal mine. Overall, the results of this study provide evidence that mining activities can contribute MPs in rural and remote rivers, with their contribution being regulated by the hydraulic and hydrological processes in the catchment.

Preparation and characterization study of composite dust suppressant based on xanthan gum

To address the critical issue of particulate matter emitted from mining operations, which poses a significant risk to human health, production safety, and the environment, a novel dust suppressant based on xanthan gum (XTG) as a coalescing agent was introduced in this study. The formulation innovatively combines anionic surfactants SDS (Sodium dodecyl sulfate) and SDBS (Sodium dodecyl benzene sulfonate) as well as nonionic surfactants OP-10, Tween-20 (Polyoxyethylene anhydrous sorbitan monolaurate) and Tween-80 (Polyoxyethylene anhydrous sorbitan monooleate) with 0.05% XTG to enhance the wettability of the solution. Considering the economy and practicality, 0.05% OP-10 + 0.05% XTG (M-OX) was finally selected as the optimal dust suppressant formulation. Through a series of experiments, including surface tension, contact angle, sedimentation, pH value, water retention, and wind erosion resistance tests, we proved that M-OX, with a pH value of 8.03, has the least impact on the environment, has better water retention, and has a significant dust suppression effect. The curing layer formed by M-OX can adapt to complex weather, maintains its integrity after rain and wind erosion, and exhibits excellent rain and wind erosion resistance. This study provides an environmentally friendly and effective dust suppression solution for surface coal mines with significant social and economic benefits.

An Embodied Intelligence System for Coal Mine Safety Assessment Based on Multi-Level Large Language Models.

Artificial intelligence (AI), particularly through advanced large language model (LLM) technologies, is reshaping coal mine safety assessment methods with its powerful cognitive capabilities. Given the dynamic, multi-source, and heterogeneous characteristics of data in typical mining scenarios, traditional manual assessment methods are limited in their information processing capacity and cost-effectiveness. This study addresses these challenges by proposing an embodied intelligent system for mine safety assessment based on multi-level large language models (LLMs) for multi-source sensor data. The system employs a multi-layer architecture implemented through multiple LLMs, enabling not only rapid and effective processing of multi-source sensor data but also enhanced environmental perception through physical interactions. By leveraging the tool invocation and reasoning capabilities of LLM in conjunction with a coal mine safety knowledge base, the system achieves logical inference, anomalous data detection, and potential safety risk prediction. Furthermore, its memory functionality ensures the learning and utilization of historical experiences, providing a solid foundation for continuous assessment processes. This study established a comprehensive experimental framework integrating numerical simulation, scenario simulation, and real-world testing to evaluate the system through embodied intelligence. Experimental results demonstrate that the system effectively processes sensor data and exhibits rapid, efficient safety assessment capabilities during embodied interactions, offering an innovative solution for coal mine safety.

An Evaluation of Eco-Environmental Quality Based on the Fused Remote Sensing Ecological Index (FRSEI) in the Jinjie Coal Mine Area, Northwest China

This study focused on the Jinjie mining area by addressing the severe resource and environmental issues arising from excessive coal mining in Shenmu County, Northwest China. Multi-source remote sensing data from GF-1 and Landsat 8 OLI were utilized in this study. Specifically, the fused remote sensing ecological index (FRSEI) was constructed to conduct a detailed evaluation and analysis of the eco-environmental quality in the mining area from 2013 to 2023. The results indicated that the overall eco-environmental quality of the Jinjie mining area exhibited a trend of initial improvement, followed by degradation, and then improvement again over the decade. The eco-environmental quality of the mine pits and their surrounding areas was significantly lower than the overall level, confirming the destructive impact of coal mining on the eco-environment. Meanwhile, as the study area, Shenmu County is actively utilizing coal mining subsidence areas to develop the photovoltaic power generation industry, aiming to achieve green and low-carbon transformation. Although the construction of photovoltaic power plants initially led to the degradation of the condition of vegetation and the FRSEI, both gradually improved after the plants were operational. Furthermore, by comparing the FRSEI with the remote sensing ecological index (RSEI) calculated solely using Landsat 8 OLI data, we found a high degree of similarity between the two, thereby validating the stability and accuracy of the FRSEI. This study not only provides high-precision data support for eco-environmental monitoring in mining areas but also highlights the potential of multi-source remote sensing data fusion technology in improving monitoring accuracy, further providing a scientific basis for formulating sustainable development strategies specifically for the eco-environment in mining areas.

Sustainable remediation of abandoned coal mines using vermicompost: a case study in Ledo coal mine, India.

Coal mining in India, especially open-cast mining, substantially strengthens the economy while concurrently causing environmental deterioration, such as soil pollution with toxic chemicals and heavy metals. This study sought to examine the efficacy of vermicompost as a remediation technique for Mine Tailing Soil (MTS) in the Ledo Coal Fields. During a 120-day duration, different concentrations of vermicompost (20%, 30%, and 40%) were administered to MTS, and the impacts on soil physicochemical parameters, fertility, and plant growth were evaluated. The findings indicated substantial enhancements in soil fertility, encompassing increased nutrient availability, improved water retention, and diminished bulk density. Plant species, including Abelmoschus esculentus, Solanum lycopersicum, and Delonix regia, showed substantial growth when subjected to 20% and 30% vermicompost amendments, with the 30% treatment producing the most remarkable outcomes. Furthermore, Risk Assessment Code values for soils amended with 20%, 30%, and 40% vermicompost were markedly diminished, reducing the bioavailability and mobility of heavy metals. The data indicate that vermicompost is an efficient and sustainable method for remediating MTS, alleviating heavy metal contamination, and enhancing plant development, thus addressing the environmental hazards of coal mining.