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Microseismic monitoring has proven to be an effective approach for detecting and preempting water inrush incidents within mining operations. However, challenges persist, particularly in terms of relying on a singular early warning index and the complexities involved in quantification. In response to these obstacles, a dedicated investigation was undertaken against the backdrop of mining activities at the 11,023 working face of Paner Coal Mine. Primarily, a novel methodology for categorizing the roof and floor into distinct zones was established based on the vertical distribution of microseismic events. Furthermore, this study delves into the dynamic evolution of key source parameters, such as microseismic energy, apparent stress, and apparent volume, amidst mining disturbances, enabling a comprehensive evaluation of the risk associated with roof and floor cracking, as well as potential water inrush incidents. A groundbreaking approach to early warning was proposed, operating on three pivotal dimensions: the depth of fractures, the intensity of fractures, and the likelihood of water inrush. Through rigorous validation during mining operations at the 11,023 working face, the efficacy was substantiated. Ultimately, the achievements offer invaluable insights and practical guidance for the advancement and implementation of water inrush early warning systems in coal mining contexts. [ABSTRACT FROM AUTHOR]

As a widely recognized and effective roadway support method, the top-cutting pressure relief technology, plays a positive role in improving the stress distribution inside the roadway and reducing the deformation of surrounding rock. To address the stress issues faced by the 1123 transportation roadway in Xichuan Coal Mine and reduce the deformation of surrounding rock, a drilling into joint and top-cutting pressure relief technology has been proposed. This technology can drill deeply into high-pressure zones, has a good pressure relief effect, and is flexible reliable, which is suitable for harder rocks in coal seams, and has high reliability and practicality. Through precise calculations using the stress function method, the upper and lower thresholds suitable for the drilling of the coal mine were determined, which are 14.14 and 6.32, respectively. The collapse state of the roof under different hole spacing was analyzed in depth using the numerical simulation method, and the stress distribution properties of solid coal before and after roof cutting were studied. The results show that the top cutting and pressure relief technology significantly improves the roof caving performance and can effectively prevent the occurrence of rockburst. At the same time, this technology can effectively reduce the stress transfer ratio, reducing the peak stress values in solid coal by 25.44% and pushing the peak point inward by 179.18%. The research results can providea reference for the selection of small coal pillar retention and support methods in the future. [ABSTRACT FROM AUTHOR]

In multi-seam coal mining, the water accumulation in the goaf of the upper coal seam will seriously threaten the safety of the lower coal-seam recovery. How to accurately determine the water charging source in the goaf and predict the amount of water accumulation in the goaf after a certain time interval has become a major challenge that urgently needs to be solved in coal production. In this study, we consider the water-discharging goaf of the Tangjiahui Coal Mine as the object of research to investigate the problem of water accumulation in the goaf during the fully mechanized caving mining of extra-thick seams of top coal. We used geochemical methods, water-accumulation space methods, and large-well methods to analyze the hydraulic connections between goaf water and other aquifers, predict the amount of water accumulation in the goaf, and explore the characteristics of water level changes over time. We then used the results to discuss the relationship between the elevation of the accumulated water and the time taken for it to fill the goaf. The results showed that there is a hydraulic connection between the water in the airspace and the goaf water (GW), roof water (RW), floor water (FW) and Ordovician limestone water (OW); the volume of water in the goaf of the working face after mining was 2,106,838.496 m3. The average rate of water accumulation was 65.407 m3/h, and the goaf was expected to have been filled in 32,211.208 h. The derived relationship between the water level and time was H 0 = − 10 − 12 t 3 + 10 − 7 t 2 − 0.0042 t + 814.61   (R 2 = 0.9837) . This study is of great significance for the sustainable development of the safety evaluation of water blocking coal pillars at the mine boundary. [ABSTRACT FROM AUTHOR]

To accurately and swiftly identifying the source of water inrush in mines, a discrimination model based on factor analysis (FA) and the moth flame optimization (MFO) algorithm coupled with least squares support vector machine (LSSVM) is proposed. Drawing from the hydrogeological conditions of the Yuanyi Mine in the Huaibei Mining Area, water samples from three aquifers were collected, and ten hydrochemical indicators were selected for the purpose of identifying the water inrush sources. Firstly, FA was performed on these ten indicators to extract five new components that can comprehensively reflect most of the information of all indicators, eliminating redundant information between the original indicators. Then, the extracted new components was used as inputs to the LSSVM model. Finally, the MFO algorithm was used to automatically optimize the two pivotal parameters of the penalty factor C and the kernel function parameter g of LSSVM, and a discrimination model based on FA-MFO-LSSVM was established. Furthermore, a comparative analysis of the discrimination performance of the FA-MFO-LSSVM model against five other models was carried out. The results unequivocally indicate that the FA-MFO-LSSVM model has high discrimination accuracy for both training and testing samples, and compared to the other five models, this model exhibits stronger discriminative performance. [ABSTRACT FROM AUTHOR]

A simple and flexible mass balance approach was applied to observations of XCH4 from TROPOMI to estimate CH4 emissions over Shanxi Province, including the impacts of advective transport, pressure transport, and atmospheric diffusion. High-frequency eddy-covariance flux observations were used to constrain the driving terms of the mass balance equation. This equation was then used to calculate day-to-day and 5 km × 5 km grided CH4 emissions from May 2018 to July 2022 based on TROPOMI RPRO column CH4 observations. The Shanxi-wide emissions of CH4, 126 ± 58.8 ug/m2/s, shows a fat tail distribution and high variability on a daily time scale (the 90th percentile is 2.14 times the mean and 2.74 times the median). As the number of days in the rolling average increases, the change in the variation decreases to 128 ± 35.7 ug/m2/s at 10-day, 128 ± 19.8 ug/m2/s at 30-day and 127 ± 13.9 ug/m2/s at 90-day. The range of values of the annual mean emissions on coal mine grids within Shanxi for the years 2018 to 2022 was 122 ± 58.2, 131 ± 71.2, 111 ± 63.6, 129 ± 87.1, and 138 ± 63.4 ug/m2/s, respectively. The 5-year average emissions from TROPOMI are 131 ± 68.0 ug/m2/s versus 125 ± 94.6 ug/m2/s on the grids where the EDGAR bottom-up database also has data, indicating that those pixels with mines dominate the overall emissions in terms of both magnitude and variability. The results show that high-frequency observation-based campaigns can produce a less biased result in terms of both the spatial and temporal distribution of CH4 emissions as compared with approaches using either low-frequency data or bottom-up databases, that coal mines dominate the sources of CH4 in Shanxi, and that the observed fat tail distribution can be accounted for using this approach. [ABSTRACT FROM AUTHOR]

This work presents particle-based numerical simulations on coal pillars in a coal mine based underground water reservoir (CMUWR). We aim to replicate the stress–strain characteristics and present the acoustic emission behavior of the coal under complex dynamic stress paths. The study reveals failure characteristics of coal exposed to monotonic/cyclic shear load under constant/cyclic normal loads. Based on the evolution of stress-time-dependent bond diameter implemented in particle model, different damage paths are established for dry and water-immersed samples under two loading frequencies. Furthermore, the numerical Gutenberg–Richter's b-value was calculated from the released energy emanating from bond failure, and this work presents the evolution of numerical Gutenberg–Richter's b-value. The numerical simulation contributes to a micromechanical understanding of the failure mechanisms of coal under water-immersion and cyclic stress, providing valuable insights for strength prediction of CMUWR. [ABSTRACT FROM AUTHOR]

Currently, hydraulic fracturing technology is widely implemented for controlling the surrounding rock and enhancing permeability in low-permeability coal seams. Evaluating the effectiveness of hydraulic fracturing is a critical component of hydraulic fracturing operations. This study addresses the challenges in assessing the location, extension angle, and initial width of fracturing fractures within the current framework of hydraulic fracturing effectiveness evaluation in coal mines. We propose utilizing single-hole reflection borehole radar to evaluate the hydraulic fracturing effect, and through numerical simulation, we analyze the response characteristics of borehole radar when detecting various hydraulic fracturing-induced cracks. Initially, five models representing hydraulic fracturing cracks and two models for non-hydraulic fracturing cracks were established. Subsequently, the responses of borehole radar with central frequencies of 100, 200, and 400 MHz to cracks of identical shapes were analyzed. Additionally, the response characteristics of borehole radar with a 200 MHz central frequency to cracks of varying lengths (1, 2, 3 m), widths (4, 8, 40 cm), and angles (90°, 45°, 15°) were examined. Finally, a comparative analysis was conducted between hydraulic and non-hydraulic fracturing cracks. A branch hole was employed to simulate a hydraulic fracturing crack, allowing for an analysis of the borehole radar's response characteristics in practical scenarios. The findings indicate that borehole radar is a viable tool for assessing hydraulic fracturing effects, providing a theoretical foundation for identifying the position of cracks, evaluating their effectiveness, and determining the regional effectiveness of the hydraulic fracturing crack system. [ABSTRACT FROM AUTHOR]

It is a difficult problem to locate the snake detecting robot in the closed complex environment of underground coal mine. The traditional localization methods usually depend on the estimation of complex ground parameters in coal mine tunnel, which leads to the complexity of establishing the localization model. In response to this compelling problem, we propose the new method to estimate the trajectory curvature and path angle of the robot, and a simple localization model of snake robot based on turning is established. On this basis, the dead reckoning localization method based on the combination of a high-precision 6-axis inertial navigation module MPU6050 and magnetic Hall encoders is proposed, which reduces the difficulty of traditional localization methods. In order to improve the localization accuracy of the robot, an algorithm combines Kalman filter and Deep learning is proposed. Firstly, the Kalman filter algorithm is used to eliminate the white Gaussian noise in the path angle signal of robot. Then, aiming at various drifts from low-frequency stage in the path angle signal, a prediction model of path angle output value based on LSTM (Long Short-Term Memory) deep neural network is established, which can predict the path angle output value for a period in the future, thereby achieving the robot's dead reckoning. The simulation and experiment results prove that the relative localization accuracy of the robot can be improved, in the simulated coal mine tunnel, the maximum relative error of the robot's location is 1.872×10-9 cm, and the maximum error of the path angle is 0.0028 rad, the determination coefficient R² is 1.000, which reflect that the established LSTM model has higher prediction accuracy, better performance, and stronger generalization ability than RBF (Radial Basis Function) neural network. The method proposed in this paper can provide a new idea for the localization problem of snake robots in the underground unstructured complex environment after the disaster. [ABSTRACT FROM AUTHOR]

By establishing an evaluation system for emergency management capability for coal mine enterprises, the problems and shortfalls in coal mine emergency management can be identified. Moreover, this evaluation method holds promise in enhancing the ability to respond to emergencies in coal mines. The current research conducts both theoretical analysis and field research to determine and extract 26 factors that impact the emergency management capability of coal mining companies. The collected data is analyzed using SPSS version 24.0 and undergoes reliability and validity assessments. Subsequently, the entropy weight technique is utilized to determine the weight of individual evaluation system indices. As an effective evaluation tool, the trained convolutional neural network (CNN) model can accurately and effectively predict the satisfaction of the samples outside the training sample set, providing suggestions for improving coal mine emergency management. The trained model is employed to make empirical predictions and analyze the XY coal mine. The findings indicate that the overall emergency management capacity of the coal mine is II, which is at a good level. The evaluation results are consistent with the actual situation, and suggestions are provided for improving the emergency management ability of coal mines. [ABSTRACT FROM AUTHOR]

Coal has remained the primary component of China's energy structure, and high-intensity extraction has continued in the central and western coal-producing regions of China. In contrast to the abundant coal resources, water resources have become extremely scarce in these regions, creating a conflict between coal resource extraction and water resource conservation. The coal mine underground reservoir (CMUR), as a typical technology for combined coal and water extraction and water-preserving coal mining, has been applied in numerous mines in central and western China. This effectively alleviates water resource shortages and achieves the goal of water resource conservation. The CMURs utilizes the goaf created by longwall mining as the water storage space. The reservoir dam structure comprises coal pillars, which serve as protective coal pillars in the mining area, and artificial dam structures that filled the gaps between these coal pillars. The stability of the dam structure under the complex stress effects of hydraulic coupling has been identified as the key to maintaining the safe operation of the CMUR. The mechanical properties, stress field, fracture field, and seepage field ("three fields") change mechanisms, as well as the research results on size optimization of coal pillar dams and artificial dams in CMURs, were systematically reviewed. The core content included the instability and failure mechanisms of dam structures under the comprehensive coupling effects of factors such as dry–wet cycles of mine water, long-term immersion, chemical effects of high-salinity water, dynamic and static loads, and cyclic loads. This paper is considered to have certain reference value for the study of the stability of dam structures in CMURs and to provide some guidance for the safe operation of CMURs. [ABSTRACT FROM AUTHOR]

Purpose. To determine the patterns of changes in the gas mixture parameters in the final gas-drainage pipeline section during draining-out of gases from the mined-out space through the gas pipeline branches with impaired throughput capacity. Methodology. Theoretical studies of gas mixture flows in mine gas-drainage pipelines, as well as the laws of gas dynamics and hydromechanics are used to solve the task set. Findings. It has been revealed that the methane concentration remains constant in the section of the gas-drainage pipeline, which is located in an uncontrolled ventilation working area. In this case, methane concentration decreases in the gas-drainage pipeline behind the insulating jumper in the zone influenced by the outlet ventilation jet. It has been found that the reduced hydraulic diameter of the gas pipeline contaminated branch leads to an increase in the absolute gas mixture pressure, a decrease in its flow rate and methane yield in the final gas-drainage pipeline section. By solving quadratic regression equations, the ratios linking the hydraulic diameter of the gas pipeline contaminated branch with the gas mixture parameters in the final gas-drainage pipeline section have been obtained. Originality. A relationship between the hydraulic diameter of the gas pipeline contaminated branch, draining-out the gas mixture from the mined-out space, and the gas mixture parameters in the final gas-drainage pipeline section has been revealed. Practical value. The obtained ratios for the hydraulic diameter of the gas pipeline contaminated branch make it possible to estimate its throughput capacity and, by the time new branches are set, if necessary, increase the discharge in the gas-drainage pipeline to maintain the necessary degasification efficiency. [ABSTRACT FROM AUTHOR]

Dust pollution for ventilation systems is a big problem for mine workers in underground coal mines. The respirable dust concentration is important to the physical and spiritual health of miners. It is hazardous up to 2 mg/m3in the air in underground coal galleries. In the present work, the airflow velocity and dust concentration values were measured at Çay 1-Kartiye roadway in Kozlu, Zonguldak. The goal of this research is modelling to the dust concentration and airflow velocity values by the computational fluid dynamics (CFD) method. An airflow and dust fluid and solid model was done using the Eularian-Granular multiphase method with the k-epsilon two-equation model. The results showed that dust concentration values were too low and fixed. The error percentage of airflow velocity values changed between 5% and 17%. Thus, this roadway is safe for coal dust explorations.

Abstract Abandoned coal mine goaf is affected by air leakages and prone to spontaneous combustion, resulting in environmental pollution and geological disasters. Haizhou Open-pit Mine adopts both underground and open-pit mining methods. During the long-term mining process, the original stable stratum structure is constantly destroyed, and the slope slides, increasing cracks and severe air leakage around the goaf and roadway. The spontaneous combustion of coal is particularly prominent after the mine shut down. At present, there is no suitable indirect monitoring method to effectively explore the spontaneous combustion area in goaf. The study developed an all-weather monitoring plan and conducted multi-point continuous long-term measurements of the spontaneous combustion state in one abandoned coal mine goaf located in the eastern part of the Haizhou Open-pit Mine. We evaluated the dynamic correlation between surface CO2 flux (SCF) and changes in the underground fire areas, determined the scope and evolution trend of the fire areas, and identified the distribution and change laws of SCF. The results show a significant positive correlation between SCF and soil temperature; moreover, the SCF value was found to reflect the CO2 emission intensity of the goaf. The high SCF in the test area showed month-wise expansion and increase, while the CO2 emission gradually increased monthly, and the calculated annual total emission was approximately 7017 t. Hence, the study can further provide guidance for the monitoring of spontaneous combustion in shallow coal seams, goaf and the assessment of CO2 emissions from underground coal fires through the on-site monitoring and analysis results.

During the coal mining process, a large amount of waste such as coal gangue and coal washing water is generated. The heavy metal pollutants in those wastes migrate and diffuse into the surrounding soil and water environment through sedimentation, runoff, leaching and other processes, posing a threat to the ecological environment. In order to study the heavy metal pollution in an abandoned coal mine area and to evaluate its ecological hazard risk, the contents of Cu, Pb, Zn, As, Cr, Ni, Hg, Cd elements in the coal gangue, water and soil samples of the mining area were detected. The single factor index method and potential ecological hazard index method were used to analyze the heavy metal pollution and its potential ecological hazard risk. The heavy metal pollution in the soil downstream of the coal washing plant in the mining area was mainly studied. The improved BCR continuous extraction method was used to analyze the forms of heavy metal elements (Cu, Zn, Cd) in the soil samples and the risk assessment coding method was employed to evaluate the bioavailability and environmental risks of heavy metal elements. The results show that: ① on average, the heavy metal contents in the coal gangue of the coal mine area are relatively low, with only Cr element content being slightly higher than that in soil. Moreover, the heavy metal element contents in the coal gangue do not exceed the risk intervention values for the soil of agricultural land, which has a little impact on heavy metal pollution in the soil. ② The heavy metal contents in the mine area’ exceed the standard, including that of Cu, Zn, Cd, Ni and As elements, and the Cd pollution is relatively serious. The pollution areas of Cu, Zn, and Ni elements are mainly concentrated in the western and southeastern parts of the gangue hill, with a certain overlap in spatial distribution. The As element pollution is distributed in the northeastern part of the gangue hill, while the Cd element pollution is widely distributed in the mine area, with moderate to severe pollution. ③ The Cd and Hg elements have potential ecological hazard risk, with a higher risk for Cd element. The comprehensive potential ecological hazard risk (RI) of heavy metal elements is mainly moderate to strong. ④ The contents of heavy metal elements in the soil downstream of the coal washing plant show an overall decreasing trend along the water flow direction, with the Cd element pollution being more severe, and the Cu, Zn, Ni, As element pollution concentrated within 200 m downstream of the coal washing plant. The heavy metal element contents of the profile sample shows a decreasing trend in the vertical direction, with no accumulation in the vertical direction. ⑤ The groundwater quality in the mine area is good, and the pH and the contents of heavy metal elements in the mine water meet the limit values of Class III surface water quality standards. The discharge of mine water drainage has a little impact on heavy metal pollution in the soil. ⑥ The proportions of acid extractable Cu and Zn elements are low, with low bioavailability, while that of Cd element is high, presenting a high-extremely high risk, with strong bioavailability and high environmental risk. Based on the current situation of heavy metal pollution in the mining area, it is recommended to further strengthen the prevention and control of heavy metal pollution, strengthen the source control, monitoring of agricultural food safety, and the investigation and research on the Cd element pollution.

Abstract A simple and flexible mass balance approach was applied to observations of XCH4 from TROPOMI to estimate CH4 emissions over Shanxi Province, including the impacts of advective transport, pressure transport, and atmospheric diffusion. High-frequency eddy-covariance flux observations were used to constrain the driving terms of the mass balance equation. This equation was then used to calculate day-to-day and 5 km × 5 km grided CH4 emissions from May 2018 to July 2022 based on TROPOMI RPRO column CH4 observations. The Shanxi-wide emissions of CH4, 126 ± 58.8 ug/m2/s, shows a fat tail distribution and high variability on a daily time scale (the 90th percentile is 2.14 times the mean and 2.74 times the median). As the number of days in the rolling average increases, the change in the variation decreases to 128 ± 35.7 ug/m2/s at 10-day, 128 ± 19.8 ug/m2/s at 30-day and 127 ± 13.9 ug/m2/s at 90-day. The range of values of the annual mean emissions on coal mine grids within Shanxi for the years 2018 to 2022 was 122 ± 58.2, 131 ± 71.2, 111 ± 63.6, 129 ± 87.1, and 138 ± 63.4 ug/m2/s, respectively. The 5-year average emissions from TROPOMI are 131 ± 68.0 ug/m2/s versus 125 ± 94.6 ug/m2/s on the grids where the EDGAR bottom-up database also has data, indicating that those pixels with mines dominate the overall emissions in terms of both magnitude and variability. The results show that high-frequency observation-based campaigns can produce a less biased result in terms of both the spatial and temporal distribution of CH4 emissions as compared with approaches using either low-frequency data or bottom-up databases, that coal mines dominate the sources of CH4 in Shanxi, and that the observed fat tail distribution can be accounted for using this approach.

Abstract This work presents particle-based numerical simulations on coal pillars in a coal mine based underground water reservoir (CMUWR). We aim to replicate the stress–strain characteristics and present the acoustic emission behavior of the coal under complex dynamic stress paths. The study reveals failure characteristics of coal exposed to monotonic/cyclic shear load under constant/cyclic normal loads. Based on the evolution of stress-time-dependent bond diameter implemented in particle model, different damage paths are established for dry and water-immersed samples under two loading frequencies. Furthermore, the numerical Gutenberg–Richter’s b-value was calculated from the released energy emanating from bond failure, and this work presents the evolution of numerical Gutenberg–Richter’s b-value. The numerical simulation contributes to a micromechanical understanding of the failure mechanisms of coal under water-immersion and cyclic stress, providing valuable insights for strength prediction of CMUWR.

Abstract Due to the low permeability characteristics of the deep gas-containing coal seam, the conventional prevention and control measures that cannot solve the problems of gas outbursts are unsatisfactory for the prevention and control of the coal and gas outbursts disaster. Therefore, in this study, a strain of methane-oxidizing bacteria M07 with high-pressure resistance, strong resistance, and high methane degradation rate was selected from coal mines. The growth and degradation abilities of M07 in chelating wetting agent solutions to assess its adaptability and find the optimal agent-to-M07 ratio. It provides a new method for integrating the reduction of impact tendency and gas pressure in deep coal mines. The experimental results show that M07 is a Gram-positive bacterium of the genus Bacillus, which has strong resistance and adaptability to high-pressure water injection. By degrading 70 mol of methane, M07 produces 1 mol of carbon dioxide, which can reduce gas pressure and reduce the risk of gas outbursts in coal mines. As the experiment proves, the best effect was achieved when the M07 concentration of the chelating wetting agent was 0.05%. The methane-oxidizing bacteria based on the chelating wetting agent as carriers prove a new prevention and control method for the integrated prevention and control of coal and gas outbursts in coal mines and also provide a new idea for microbial application in coal mine disaster control.

China is a country in the world with the serious environmental pollution of coal mine “three wastes” (solid, liquid, gas). A lot of in-depth research and practice has been carried out on the utilization and treatment of “three wastes”. However, there are still many problems such as imperfect standards and norms, small scale of treatment and unsound technology. In order to solve the problem of synergistic development of low-cost geological storage of large-scale “three wastes” and ecological environment in China’s coal mines, on the basis of the definition of geological storage in other countries, the connotation of geological storage in China has been expanded. The progress and current status of research on the geological storage of “three wastes” are analyzed. Literature and patents related to the geological storage of “three wastes” at home and abroad are reviewed. The problems faced by China in carrying out the geological storage of “three wastes” and the suggestions for further development are put forward. It is pointed out that the main problem faced by the geological storage of “three wastes” in China is the inadequacy of the standards and regulations in the field of environment, especially the extensive lack of standards for the deep-well injection of waste liquids. The systematic research has shown that the research institutions in China are paying increasing attention to research in the field of the geological storage of the “three wastes”, and that the results of the research account for a high percentage of research in the world. China’s coal mine “three wastes” geological storage and ecological environment synergistic development awareness and system is being formed. However, there is insufficient support for research on the large-scale geological storage of “three wastes”, the cyclic system of geological storage of “three wastes” in the whole cycle of coal mining, and the synergistic relationship between CO2 capture, utilization and storage (CCUS) technology and the ecological environment. This seriously restricts the large-scale implementation and application of the concepts, technologies and projects of geological storage. China should expeditiously strengthen the scientific and technological research and development of coal mine “three wastes” geological storage technology and ecological environment synergistic development. Through the establishment of improved standards and norms, increased technological research and development, and strengthened environmental supervision and other measures, the green and sustainable development in China’s coal mines is promoted, helping the China’s “dual-carbon” goal to be realized.

The main scientific and practical results of the study and assessment of ventilation control in coal mines using the decomposition method based on data from the analysis of aerodynamic parameters of air distribution are presented. This will lead to increased safety and reduced accident rates in mining operations at coal mines. Methods of decomposition, statistical dynamics, set theory, fundamental laws of mining aerodynamics, and discrete mathematics are described. The studies were carried out based on the experimental data of the authors using various mathematical and statistical methods. A universal technique is proposed that can be used in mine workings for analysis, assessment of ventilation processes and associated aerodynamic factors, as well as optimization of the air distribution control system under various operating modes. A methodology and application software developed on its basis have been compiled. Automated geographic information systems such as GIS K-MINE® (Krivoy Rog, Ukraine) and VENTSIM are recommended. This system has been approved by regulatory authorities in Ukraine and is utilized by specialists from industry institutes, State Mining Supervision authorities, mines, and others. They are adapted for coal mines, ensuring increased safety and efficiency of work. This will ensure increased safety, labor protection, and reduced accident rates in coal mining operations. [ABSTRACT FROM AUTHOR]

As the medium of geological information, groundwater provides an indirect method to solve the secondary disasters of mining activities. Identifying the groundwater regime of overburden aquifers induced by the mining disturbance is significant in mining safety and geological environment protection. This study proposes the novel data-driven algorithm based on the combination of machine learning methods and hydrochemical analyses to predict anomalous changes in groundwater levels within the mine and its neighboring areas induced after mining activities accurately. The hydrochemistry analysis reveals that the dissolution of carbonate and evaporite and the cation exchange function are the main hydrochemical process for controlling the groundwater environment. The anomalous change in the hydrochemistry characteristic in different aquifers reveals that the hydraulic connection between different aquifers is enhanced by mining activities. The continuous wavelet coherence is used to reveal the nonlinear relationship between the groundwater level change and external influencing factors. Based on the above analysis, the groundwater level, precipitation, mine water inflow, and unit goal area could be considered as the input variables of the hydrological model. Two different data-driven algorithms, the Decision Tree and the Long Short-Term Memory (LSTM) neural network, are introduced to construct the hydrological prediction model. Four error metrics (MAPE, RMSE, NSE and R2) are applied for evaluating the performance of hydrological model. For the NSE value, the predictive accuracy of the hydrological model constructed using LSTM is 8% higher than that of Decision Tree algorithm. Accurately predicting the anomalous change in groundwater level caused by the mining activities could ensure the safety of coal mining and prevent the secondary disaster of mining activities. [ABSTRACT FROM AUTHOR]

In accordance with the programme of closure works and the implementation of ecological spatial rehabilitation in the area of the Slovenian coal mine Trbovlje–Hrastnik (RTH), there is a great opportunity to exploit shallow geothermal energy from water and ground sources. In the RTH area, there is great energy potential in the utilisation of underground water and heat from the earth. In our research, we have focussed on the use of geothermal energy with heat pumps from groundwater (water/water system) and from ground collectors and wells up to a depth of 150 m (rock/water system). With the water/water system, we have an average of 2.7 MW of thermal energy available, with the rock/water system having 7.5 kW of thermal energy from a 150 m deep well. With the rock/water system in particular, the development of an industrial zone in the RTH area can also provide for a greater demand for thermal energy. The thermal energy obtained in this way is utilised via heat pumps to heat and cool commercial, residential and industrial buildings. The utilisation of shallow geothermal energy can make a major contribution to carbon neutrality, as the use of geothermal energy has no negative impact on the environment and causes no greenhouse gas emissions. The aim of the paper is to provide an overview of the methods used to analyse heat storage in aquifers of abandoned coal mines, to represent these storages in RTH with a basic mathematical–statistical inventory of what is happening in the aquifer, and to investigate the possibility of using shallow geothermal energy with the help of modelling the use of shallow geothermal energy. The results and analyses obtained can make an important scientific contribution to the use of geothermal energy from abandoned and closed mines. [ABSTRACT FROM AUTHOR]

China is likely the world's largest anthropogenic source of methane emissions, with coal mine methane (CMM) being the predominant contributor. Here, we deploy 2 years of satellite observations to survey facility‐level CMM emitters in Shanxi, the most prolific coal mining province in China. A total of 138 detected episodic events at 82 facilities are estimated to emit 1.20 (+0.24/−0.20, 95% CI) million tons of methane per year (Mt CH4/yr) during 2021–2023, roughly equivalent to 4.2 times the integrated flux from the Permian plumes and four times of the integrated flux from the Four Corners plumes, two of the world's largest hotspots for oil and gas methane emissions. This work reveals the heavy‐tailed distribution characteristic of CMM emission sources for the first time, with 20% of emitters contributing approximately 50% of total emissions. Comparison with the Global Energy Monitor (GEM) inventory reveals that the GEM estimate is about 4.1 times our estimate. Plain Language Summary: This study examines methane emissions from coal mines in Shanxi, China, identified as a significant source of global methane, a potent greenhouse gas. Using satellite data over 2 years, we found 138 detected episodic events at 82 facilities in Shanxi emitting an estimated 1.2 million tons of methane annually, far exceeding emissions from known global hotspots in the oil and gas sectors. Our analysis shows that a small percentage of these facilities contribute to the majority of emissions. The results, which challenge previous estimates from environmental monitoring organizations, underscore the need for direct, observational methods to accurately assess and address methane emissions. This work aims to guide efforts in mitigating climate change by identifying key areas for reducing methane release. Key Points: Satellite data identify 82 major methane emitters in Shanxi, China, with high annual emissions of up to 1.2 MtTop 20% of coal mines contribute to half of the region's total methane emissionsFindings highlight the importance of direct measurements for accurate emission estimates [ABSTRACT FROM AUTHOR]

China faces a challenge in the sustainable development of the coal industry due to pneumoconiosis problems. Dust control technologies are crucial for safe production and miners' health, ensuring the industry's longevity. This article reviews the development process of dust prevention and control in underground coal mines in China, summarizes various technologies, and divides them into dust suppression, open-space dust reduction, and mine dust collectors according to different stages and environments of use. In dust suppression technologies, coal-seam water injection can reduce total dust generation by 60%, wet rock drilling can reduce drilling dust in the presence of stable water sources and high-pressure bearing equipment, and water-seal blasting can reduce blasting dust by 50–70%. In open-space dust reduction technologies, spray dust suppression can remove total dust by 50–95% and the removal efficiencies of foam dedusting for total and respirable dust are reported to reach 95% and 85% under the right conditions, respectively. In dust collector technologies, dry collectors can remove 80–95% of total dust. Wet collectors achieve up to 90% efficiency, dependent on water supply and waste processing. This article also discusses vapor heterogeneous condensation technology as a promising method for improving respirable dust removal in humid mine environments. [ABSTRACT FROM AUTHOR]

The activation movement of overburden rock in mined-out areas can lead to surface movement and threaten the safety of surface buildings. To avoid such disasters, taking the mined-out areas (MOA) of Baiping in China as the engineering background, a site survey was conducted to analyze the overburden rock state of the shallow MOA. The surface movement and deformation characteristics were numerically simulated to investigate the stability of surface buildings above the MOA. Results show that, the uneven settlement of the MOA can be divided into neutral, compression and tension zones. The settlement boundary angle of the MOA is approximately 55-59°, and a larger range of the MOA corresponds to a greater impact of the surface settlement. The 100 mm settlement line on the surface of the MOA is approximately 100 m from the stop-mining line. In the range of 50-70 m from the stop-mining line, the settlement of the residential buildings is approximately 0.6-0.8 m, and the tilting deformation is approximately 1.0-1.5 mm/m. When the distance among the buildings and the stop-mining line exceeds 100 m, the uneven settlement of the surface will have less impact on the surface buildings. The obtained conclusions provide a significantly technical support to evaluate the stability of the surface buildings in MOA [ABSTRACT FROM AUTHOR]

Hidden hazard risks of coal mine gas accidents significantly threaten the safety production of coal mine enterprises. Determining how these hidden hazard risks can be recognized and analyzing their action relations is a problem that the business and academic circles must urgently solve. To determine the action paths among hidden hazard risks of coal mine gas accidents and formulate scientific control measures, typical coal mine gas accidents during 2013–2023 in China were reviewed and analyzed based on the “human-equipment-environment-management” framework by combining the accident-causing theory. Twenty influencing factors were recognized and extracted using the grounded theory. Then, the degree centrality and betweenness centrality were determined for the influencing factors using methods derived from social network analysis. The hierarchy of influence of factors was determined, and the risk propagation mechanism in the system network was disclosed. Results reveal that coal safety management system and implementation, degree of safety standardization, investment in safety technology, and gas concentration have higher relative centrality than others. This finding reveals that these factors have a relatively higher influencing intensity on the risk system of coal mine gas accidents and have strong controls in the accident system. The key risk factors can easily intensify hidden hazard risks and cause the occurrence of accidents. The obtained conclusion provides a new decision-making idea for control coal mine gas risks. [ABSTRACT FROM AUTHOR]

Human activities have seriously affected the quality of shallow groundwater in coal mining areas and understanding the spatial and temporal evolution of groundwater is a widespread concern. This study was conducted to determine the primary hydrogeochemical processes in the Sunan Mining region, China. We collected 84 groundwater samples from a Quaternary loose aquifer and tested the macronutrient content using standard methods. Multivariate statistical analysis and hydrochemical analysis were conducted to analyze the sources and formation mechanisms of groundwater constituents in the early, middle, and late stages of mining. Results show that the water quality evolved from Cl·SO4-Na.Ca type to SO4-Na.Ca type. Mineral dissolution, halite dissolution, cation exchange, and desulfurization primarily occurred in the groundwater, and the hydrogeochemistry was strong in the northern part of the study area; however, the degree of both dissolution and reaction gradually weakened with increasing mining activities. [ABSTRACT FROM AUTHOR]

Coal mining is crucial to satisfying energy demands. However, mining activities create structural and functional changes and release potentially toxic elements (PTEs). Interaction between PTEs and soil physicochemical properties is bidirectional. Therefore, modelling interactions and predicting PTEs is critical for mitigating the consequences of mining activities on soil. The current study is being conducted in Jharkhand state, India, in active mining, abandoned mining, and non-mining locations, to determine soil physicochemical and metallic characteristics. Statistical analysis, including chemometric analysis and multiple linear regression (MLR), was used to investigate the impacts of bidirectional interactions of soil parameters on PTEs. Metals such as Co, Cr, Pb, and Ti have been identified as PTEs. Chemometric study found that PTEs in mining sites are the result of mining activities, but PTEs in non-mining and abandoned mine sites are geological in origin. During the active mining period, mining alters the soil profile and raises PTE concentrations above critical thresholds. The MLR models applied to PTEs of non-mining and active mining sites had R2 values ranging from 88.80% to 99.97%, indicating that a well-defined soil profile allows us to forecast PTEs with high accuracy. In non-mining areas, the PTE concentration is substantially within the critical limits. However, coal mining alters the soil profile and releases PTEs into the earth by breaking down the soil metal complex. The loosened soil contains PTEs in the form of ions or water-dissolved particles. The disturbed soil profile of an abandoned mine makes PTE prediction difficult (R2 prediction as low as 23.43%). Leaching, runoff water, evaporative loss, and phytoremediation processes all help to wash PTEs out of soil over time. Once the soil begins to consolidate into a stable soil profile, the necessary metals, which are more reactive than PTEs, dissociate and bind to the soil complexes restoring the soil health. [ABSTRACT FROM AUTHOR]

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study assesses the concentration, probabilistic risk, source classification, and dietary risk arising from heavy metal (HMs) pollution in agricultural soils affected by coal mining in eastern part of India. Analyses of soil and rice plant indicated significantly elevated levels of HMs beyond the permissible limit in the contaminated zones (zone 1: PbSoil: 108.24 ± 72.97, CuSoil: 57.26 ± 23.91, CdSoil: 8.44 ± 2.76, CrSoil: 180.05 ± 46.90, NiSoil: 70.79 ± 25.06 mg/kg; PbGrain: 0.96 ± 0.8, CuGrain: 8.6 ± 5.1, CdGrain: 0.65 ± 0.42, CrGrain: 4.78 ± 1.89, NiGrain: 11.74 ± 4.38 mg/kg. zone 2: PbSoil: 139.56 ± 69.46, CuSoil: 69.89 ± 19.86, CdSoil: 8.95 ± 2.57, CrSoil: 245.46 ± 70.66, NiSoil: 95.46 ± 22.89 mg/kg; PbGrain: 1.27 ± 0.84, CuGrain: 7.9 ± 4.57, CdGrain: 0.76 ± 0.43, CrGrain: 8.6 ± 1.58, NiGrain: 11.50 ± 2.46 mg/kg) compared to the uncontaminated zone (zone 3). Carcinogenic and non-carcinogenic health risks were computed based on the HMs concentration in the soil and rice grain, with Pb, Cr, and Ni identified as posing a high risk to human health. Monte Carlo simulation, the solubility-free ion activity model (FIAM), and severity adjusted margin of exposure (SAMOE) were employed to predict health risk. FIAM hazard quotient (HQ) values for Ni, Cr, Cd, and Pb were > 1, indicating a significant non-carcinogenic risk. SAMOE (risk thermometer) results for contaminated zones ranged from low to moderate risk (CrSAMOE: 0.05, and NiSAMOE: 0.03). Fuzzy-TOPSIS and variable importance plots (from random forest) showed that Ni and Cr were mostly responsible for the toxicity in the rice plant, respectively. A self-organizing map for source classification revealed common origin for the studied HMs with zone 2 exhibiting the highest contamination. The positive matrix factorization model for the source apportionment identified coal mining and transportation as the predominant sources of HMs. Spatial distribution analysis indicated higher contamination near mining sites as compared to distant sampling sites. Consequently, this study will aid environmental scientists and policymakers controlling HM pollution in agricultural soils near coal mines. [ABSTRACT FROM AUTHOR]

Although it is well known that groundwater significantly influences the plant communities, there have been few studies on how the soil and plant communities respond to a rapid decline of groundwater in a short time affected by coal mining. This paper focuses on the examination of changes in groundwater depth before and after coal mining and the soil‐vegetation response in a typical semi‐arid grassland coal mine area of Hulunbuir Steppe, Northeastern China. The IsoSource model, based on the dual stable isotopes of δ D and δ18O, was employed to estimate groundwater contributions to shallow soil (0–100 cm) water under different groundwater depths. The results revealed that groundwater was the dominant water source (75.7% ± 17.1%) for shallow soil water when the groundwater depth is less than 4 m, indicating that 4 m is a threshold in groundwater depth, separating groundwater‐dependent, and precipitation‐driven vegetation system in the study area. Secondly, a strong nonlinear response was observed between vegetation species, height, coverage, and the decline in groundwater. The vegetation properties were found to be the lowest in the areas where groundwater depth increased from 1.5–4 m to 4–28 m before and after coal mining. Finally, the groundwater level decline in the mining area significantly influenced the groundwater‐dependent vegetation ecosystem, the soil cation exchange capacity and organic matter reduced lead to the degradation of plant communities and the transition of mesophytes to xerophytes. Besides, the soil‐vegetation system in the non‐groundwater‐dependent area has no obvious response to the groundwater decline. These results suggest that caution should be exercised when mining in groundwater‐dependent ecosystem regions. [ABSTRACT FROM AUTHOR]

Underground coal mining of gas-bearing coal seams is accompanied by the emission of large amounts of methane, which increases with depth. Coal seam methane is not only a major cause of major accidents in coal mines, but is also a greenhouse gas that has a significant negative impact on the Earth's atmosphere. Analysis of the efficiency of underground coal mining suggests that as the depth of mining increases, the productivity of a longwall decreases by a factor of 3–5 or more, while the specific volume of methane emitted increases manifold and the efficiency of methane management decreases. Effective management of coal seam methane can only be achieved by monitoring its content at key points in a system of workings. Monitoring of methane not only eliminates the risk of explosions, but also lets us assess the effectiveness of using methane management techniques and their parameters to improve efficiency and reduce the cost of methane management (including a methane drainage) for ensuring sustainable underground coal mining. The aim of this article is to develop a software and hardware complex for monitoring methane in a coal mine by creating a simulation model for monitoring methane. The Arduino Uno board and the methane sensor MQ-4 were used for this purpose. In this article, the causes of methane emissions in coal mines, gas control systems, the structure of the mine monitoring system, and the causes of risks and occurrence of accidents in coal mines are considered. As a result of the work, the mathematical model of the methane measurement sensor was developed; the Arduino Uno board developed a simulation system for methane monitoring; and the numerical results of the research are presented in the graphs. [ABSTRACT FROM AUTHOR]

In recent years, the deformation detection technology for underground tunnels has played a crucial role in coal mine safety management. Currently, traditional methods such as the cross method and those employing the roof abscission layer monitoring instrument are primarily used for tunnel deformation detection in coal mines. With the advancement of photogrammetric methods, three-dimensional laser scanners have gradually become the primary method for deformation detection of coal mine tunnels. However, due to the high-risk confined spaces and distant distribution of coal mine tunnels, stationary three-dimensional laser scanning technology requires a significant amount of labor and time, posing certain operational risks. Currently, mobile laser scanning has become a popular method for coal mine tunnel deformation detection. This paper proposes a method for detecting point cloud deformation of underground coal mine tunnels based on a handheld three-dimensional laser scanner. This method utilizes SLAM laser radar to obtain complete point cloud information of the entire tunnel, while projecting the three-dimensional point cloud onto different planes to obtain the coordinates of the tunnel centerline. By using the calculated tunnel centerline, the three-dimensional point cloud data collected at different times are matched to the same coordinate system, and then the tunnel deformation parameters are analyzed separately from the global and cross-sectional perspectives. Through on-site collection of tunnel data, this paper verifies the feasibility of the algorithm and compares it with other centerline fitting and point cloud registration algorithms, demonstrating higher accuracy and meeting practical needs. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Based on the production conditions of the 10103 excavation working face of the Baozigou coal mine, this paper analyzes the potential sources of H2S and the expected emission concentrations of H2S in the working face. Considering the previous engineering practice for controlling H2S disasters in coal mine working faces, numerical simulations were conducted to investigate air flow and H2S migration and diffusion in the tunnel in the excavation working face. The migration and distribution of H2S in the coal seam mining face were studied, and the effects of outlet wind speed, duct location, and duct diameter on the H2S concentration distribution were explored. The higher the outlet wind speed, the more conducive to the emission of H2S gas, but too high a wind speed will be detrimental to the concentrated extraction and purification absorption of H2S; the closer the outlet position of the air duct is to the end of the working surface, the lower the H2S concentration in the vortex area at the corner; the air duct If the diameter is too small, the harmful gases released from hard-to-break coal cannot be entrained and taken away. When the diameter of the air duct is too large, the entrainment volume during the jet process will be expanded. To verify the field distribution of H2S concentration at the bottom, middle, and top of the boring machine, a CD4-type portable H2S instrument was used to analyze the distribution of H2S near the excavation working face.

The highly-efficient treatment of coal mine water with low energy consumption contributes to much safer and more efficient coal mining. At present, mine water processing at underground is still limited for its small treatment water yield, large land coverage and high operation cost in ground treatment, high drainage costs when mine water is discharged into the surface water system. In this light, this study puts forward the "deep ground-underground-surface ground" linkage system for mine water treatment and utilization. The treated mine water is partially used for mining production and residential usage, while the rest is subject to deep reinjection or drainage. This paper first introduces the operational mechanism behind this system, and then evaluates its validity in terms of water quality, water quantity, hydrogeology, underground structure, and feasibility of recharge engineering. This study then reviews existing mine water treatment methods for varying water qualities and the "underground-surface" joint treatment system; Also, a summary is drawn regarding the selection of aquifer for reinjection purposes, reinjection construction operations, reinjection tests, simulation of reinjection water quality, and analysis of reinjection safety.

Despite the implementation of various technological solutions, underground coal mining has a significant environmental impact. This paper focuses on the impact of underground coal mines on the environment, with particular emphasis on such mining activities in the Republic of Serbia and stresses the importance of monitoring as a phase of environmental protection. The current practice of environmental monitoring in underground coal mines in the Republic of Serbia lacks systematic and comprehensive procedures, making this research paper an original and significant contribution to the mining industry. The primary objective of this research is to investigate the interaction between underground mining operations and the environment, provide a realistic assessment of the environmental impacts, and emphasize the importance of measuring certain parameters. A conceptual model of environmental monitoring, encompassing global trends and research, as well as the existing institutional framework in the Republic of Serbia, has been developed in this paper. Consistent implementation of this model can help establish quality procedures to reduce the impact of underground coal mining on the environment. The research demonstrates that the parameters with the greatest direct impact on the environment are the mine air (i.e. methane), waste rock disposal, ground subsidence, and indirect impacts such as electricity consumption. These influential parameters are analysed using the example of the Soko brown coal mine.

As one of the important energy industries, the safe production of coal mines not only concerns the safety of employees, but also affects the sustainable development of society. Recent rescue cases have shown that the layout of material bases and the allocation of emergency materials need to be further optimized. For this problem, this paper adopts the material hierarchical reserve mode for the first time, combining the material hierarchical reserve mode, multi-level material bases selection model, and the Fuzzy Analytic Hierarchy Process (FAHP) method to determine the optimal location of the coal mine material bases in Liaoning Province. Determine the reserve level of emergency materials through evaluation and clustering analysis of various emergency materials. Improve the traditional gravity model and construct a multi-objective planning model for multi-level material bases site selection. Apply the reserve level of emergency materials and real regional data to the site selection model, and use the Non-dominated Sorting Genetic Algorithm III (NSGA-III) to solve the model. Then, the optimal site selection scheme was selected using FAHP, and sensitivity analysis was conducted. The research results indicate that: 1) 9 county-level, 6 city-level and 2 provincial-level material bases will be constructed; 2) location selection of material bases is not only affected by costs, but also by the density of road networks; 3) use of hierarchical material reserve mode can significantly reduce the construction cost of material bases. Compared to the traditional material reserve mode, it can reduce costs by 86.6%. Compared to a single-level material bases, it can still reduce costs by 74.7%. The research results of this paper can be used for the selection of emergency material bases and the allocation of emergency material reserves, which can reduce costs and promote the improvement of regional emergency rescue capabilities.

AbstractFaults significantly affect the stability of surrounding rock and stress distribution, which increases the possibility of water inrush disasters in a coal mine. Also, the precisely advanced prevention and control of floor limestone water become the foundation of ensuring mine safety and efficient production in coal mines. Fault development evaluation is one of the elements that control further transparent and fine studies. In this paper, the fault control index (FCI) is built based on the fractal dimension (Ds) and fault influence factor (E), which is determined according to the measured water inflow of water inrush points. The box meshing level is analyzed to calculate and compare the FCI. The results show that the box-meshing level affects the value of Ds and FCI and a meshing level of 6 seems to be the minimum standard of Ds for high accuracy. To verify the results, a comprehensive risk evaluation model of floor water inrush is established to illustrate the implications of fault complexity degree on safety mining. A stricter meshing grade when using the box-counting method in fault complexity degree is necessary for further studies in the precise prevention and control of mine hazards.

Based on the production conditions of the 10103 excavation working face of the Baozigou coal mine, this paper analyzes the potential sources of H2S and the expected emission concentrations of H2S in the working face. Considering the previous engineering practice for controlling H2S disasters in coal mine working faces, numerical simulations were conducted to investigate air flow and H2S migration and diffusion in the tunnel in the excavation working face. The migration and distribution of H2S in the coal seam mining face were studied, and the effects of outlet wind speed, duct location, and duct diameter on the H2S concentration distribution were explored. The higher the outlet wind speed, the more conducive to the emission of H2S gas, but too high a wind speed will be detrimental to the concentrated extraction and purification absorption of H2S; the closer the outlet position of the air duct is to the end of the working surface, the lower the H2S concentration in the vortex area at the corner; the air duct If the diameter is too small, the harmful gases released from hard-to-break coal cannot be entrained and taken away. When the diameter of the air duct is too large, the entrainment volume during the jet process will be expanded. To verify the field distribution of H2S concentration at the bottom, middle, and top of the boring machine, a CD4-type portable H2S instrument was used to analyze the distribution of H2S near the excavation working face. [ABSTRACT FROM AUTHOR]

Coal Mine monitoring is a critical task to ensure the safety of Miners and efficient mining operations. Traditional methods of monitoring rely on wired sensors, which are expensive to install and maintain. Wireless technologies offer a cost-effective and flexible solution to this problem. In this context, the use of the ESP-NOW protocol is proposed as a means of transmitting data from sensors in a Coal Mine to a central monitoring system where the data is processed and analysed in real time. ESP-NOW is a low-power wireless communication protocol that can be implemented on Node MCU. The proposed system can collect data from various sensors, including gas sensors, Temperature sensors, Particulate Matter sensors, and Humidity sensors, and send the data wirelessly to the nodes that are fixed at different locations on a tunnel surface that is connected to the central monitoring station. The system can detect potential safety hazards and provide early warning alerts to Mine operators as well as it is used in tracking the workers. The results demonstrate the effectiveness of ESP-NOW in Coal Mine monitoring where real-time data transmission is critical. [ABSTRACT FROM AUTHOR]

222Rn activity was measured in Asansol city and the adjacent mining area, West Bengal, India. 222Rn concentrations were found to vary in the range 6.4–145, 1080–91002, and 2070–180000 Bqm−3 in indoor air, soil gas, and groundwater, respectively. Total effective doses (TEDs) due to 222Rn exposure were also estimated. In some sampling locations, TEDs appear to exceed the maximum permissible limit (100 µSvy−1). 222Rn concentration variation contour mapping was prepared. Carcinogenic health risk factors (HRF) due to 222Rn activity were also estimated. In some places, HRFs are found to be very high (> permissible limit ~ 1.0). [ABSTRACT FROM AUTHOR]