To address the technical challenges of end-zone top coal recovery which is loacted over roadwagys and transition supports in thick-seam fully mechanized top coal caving mining face, based on the deformation characteristics of the roof strata in end-zone, a technology of end-zone top coal recovery through lagging end-zone coal caving supports in a fully mechanized top coal caving face is proposed by combining theoretical analysis, numerical simulation and field application. The caving-capable supports in the end zone are arranged 2–3m lagging behind the working face supports torward the direction of goaf, and the transfer machine and the rear scraper conveyor are extended to the end of the coal caving supports in end-zone of the working face. At the same time, the transition supports with coal caving function are adopted, and the top coal of the whole working face and the top coal of the mining roadways can be recovered by using the coal transportation equipment of the original working face. Multiple validated top coal fracturing technologies have been implemented, including anchor withdrawing, mesh cutting, gas explosion fracturing, and static expansion fracturing. Applicaton of the technology of recoverying end-zone top coal through lagging end-zone coal caving supports in a fully mechanized top coal caving face in Sanyuan coal mine shows that about 72 tons of top coal resources can be additonnally recovered for every 1m mining, and the recovery rate of the working face is increased by 2.5%. The safe and efficient recovery of the top coal of the mining roadways and the top coal of the transition support has not only achieved remarkable economic benefits, but also promoted the safe, efficient and sustainable mining of the mine.

Addressing the challenge of coal extraction beneath villages located on the lower plate of a fault in the Dashi Mine of the Fengfeng Mining Area of Jizhong Energy, and considering the geological conditions of the mining area, an optimized grouting and subsidence reduction scheme for overburden separation was designed. Measures were proposed to address abnormal conditions influenced by the fault. Based on the fault conditions revealed by on-site drilling, the drilling layout was adjusted to achieve grouting reinforcement in the separation zones of the upper and lower plates of the fault, as well as in the fault fracture zone. The cumulative grouting volume on the 03 working face reached 178,300 tons, with a total injection-extraction ratio of 55%. Analysis of the grouting volume in the upper and lower plate areas revealed that coal seam mining activates the upper fault, leading to the formation of separation spaces in the lower plate, while the upper plate has limited capacity to form separation spaces. For grouting in the overburden separation layer influenced by the fault, it is advisable to appropriately increase the number of treatment holes in the upper plate to ensure effective treatment, and to increase the grouting volume in the lower plate space to effectively fill the separation zone. Using the probability integral method to predict surface subsidence on the 03 working face, it was calculated that the maximum surface subsidence during conventional mining reached 2200mm. After implementing the overburden separation grouting technology for subsidence reduction, the maximum surface subsidence decreased to 1025mm, with an estimated subsidence reduction rate of 53.4%. The on-site surface subsidence monitoring results show that the surface subsidence above the 03 working face first increases and then decreases, with the maximum subsidence located in the middle of the working face, with a subsidence amount of 768mm, and the subsidence reduction effect is good.

In view of the industry characteristics of the current emergency management work, such as the prominent main responsibility, time efficiency first, limitations and pertinence, combined with the typical problems such as the inadequate implementation of the main responsibility of the coal mine, the nonstandard emergency response and disposal, and the insufficient participation in emergency rescue, taking digital technology, fusion technology and management decision technology as the core, and the idea of disaster chain as the guidance, the coal mine emergency management system architecture was studied, and the emergency management system with major disaster risk monitoring and early warning, emergency auxiliary decision-making, emergency coordination command and emergency summary and evaluation as the main functional modules was developed. The field test results show that the system has reasonable functional architecture and clear business logic, and it has a positive effect on strengthening the digital ability of coal mine emergency management and promoting the scientific and refined emergency management.

This article takes the water quality characteristics of mine water in the border area between Inner Mongolia and Shaanxi, the existing problems in the original treatment process, and the modification of the salt separation equipment as the starting point. It provides a detailed introduction to the modification project of the freezing crystallization unit in the deep treatment process of mine water. It summarizes the application effects of the modification scheme. The implementation of this project has addressed issues such as poor freezing crystallization effects during the operation of the original process, frequent floating nitrate in the effluent affecting the salt purity of sodium chloride products, and the inability of facilities and equipment to operate continuously and stably.

The Shen-wei pipeline coal transport project is subject to the environmental protection industrial policy of the Guanzhong region, and the large gap between the transportation capacity of pipeline coal transport (10 million tons/year) and the consumption capacity of the terminal chemical plant leads to a large surplus of coal slurry. In order to ensure the safe and stable operation of coal transport pipeline and the best comprehensive benefit of coal transport pipeline, surplus coal slurry needs to be dehydrated and sold. At present, there is no engineering case of this scale in China for reference. Combining the product characteristics of coal slurry after dehydration (fine, wet and sticky) and the design experience of Shen-wei pipeline coal transport project phase I, the scheme selection and optimization design of each process system of storage and loading are carried out. At present, the surplus coal slurry application engineering storage and loading system has been running stably for 3 years, and has transported about 20 million tons of coal in total, which has created good benefits for enterprises.

Aiming at the control problem of surrounding rock of gob-side entry with small coal pillar in medium-thick coal seam, taking 8226 air roadway of Xutuan Coal Mine as the research object, the causes of surrounding rock deformation of gob-side entry under the existing support scheme are analyzed using theoretical analysis and field measurement. The results show that the main reasons for the large deformation of the surrounding rock in the roadway are the low strength-stress ratio of the coal body, the poor integrity of the coal body, the influence of the mining dynamic pressure, and the unreasonable support from and parameters. Based on this, a pre-stressed bolting and shotcrete support technology combining ' high pre-stressed anchor net cable strong primary support + pre-stressed anchor cable injection + roadway side reinforcement during mining dynamic pressure influence ' is proposed and applied in the field. The engineering application shows that after implementing this technology, the displacement of the two sides of the gob-side roadway is 150 ~ 200 mm, and the roof subsidence is 50 ~ 100 mm. The surrounding rock deformation of the gob-side roadway is effectively controlled, which can provide a reference for the surrounding rock control under similar conditions.

Gob-side entry driving with small coal pillars is an effective means to control rock burst disasters. By establishing the motion mechanics model of the overlying rock structure on the free side of the gob-side roadway, the expressions of the rotation angle of the overlying key block and the support force of the coal pillar after the roadway excavation are obtained. Combined with the numerical simulation, the influence of the width of the coal pillar on the rotation angle of the overlying key block and the stress evolution law of the coal pillar is studied. The results show that with the increase of the width of the coal pillar, the rotation angle of the overlying key block decreases gradually, and the relationship between them is exponential function. The supporting force of the coal pillar increases exponentially, and the peak stress of the mining side does not change significantly, but the distance between the peak position and the coal wall of the mining side increases gradually. With the increase of the thickness of the coal seam, the rotation angle of the overlying key block increases linearly, and the supporting force of the coal pillar decreases exponentially. It is determined that the width of the coal pillar in the 6305 working face of Xinjulong Coal Mine is 4.5 m. The deformation of the surrounding rock of the roadway is small during the mining process. The microseismic events are mostly concentrated in the coal pillar area, and there is no large energy event in the overlying rock on the free side. The width of the coal pillar is reasonable and contributes to the slow release of roof energy.

In order to solve the technical difficulties in controlling the deformation of surrounding rock in deep well high stress soft rock tunnels, taking the No. 2 main drainage bin of Yadian Coal Mine as the research background, the distribution of rock stress, mineral composition and content of surrounding rock were tested, the deformation and failure characteristics of surrounding rock were analyzed, and the influencing factors and mechanisms of deformation in high stress soft rock tunnels were studied. The results show that the deformation of the surrounding rock in the roadway is mainly manifested by strong bottom bulging and severe internal squeezing of the roadway walls. The content of expansive clay minerals in the surrounding rock is as high as 95%. The strength attenuation and structural degradation of the surrounding rock when it encounters water are prominent, which constitute the main internal factors affecting the deformation of the surrounding rock. Low support strength and high geostress constitute the main external factors affecting the deformation of the surrounding rock. The initial support strength of the roadway is low, and the anchor rods and cables have not effectively played their active support role. Under high stress, the integrity and strength of the surrounding rock continue to weaken, resulting in gradual instability and failure of the full section roadway from shallow to deep. This reveals that the key to deformation control of high stress soft rock roadway lies in building a stable anchoring bearing structure. Based on this, the full section anchoring and grouting support technology is proposed, which improves the integrity and strength of the surrounding rock through grouting modification. The bottom plate grouting and anchoring achieve full length anchoring with internal anchoring and external grouting. Combined with the active support effect of the anchor rods and cables, a high prestressed anchoring and grouting bearing area is formed to improve the overall structural stability of the roadway. The underground application effect shows that after grouting modification, the integrity of the surrounding rock structure is significantly improved, the surface displacement of the roadway surrounding rock is significantly reduced, and the deformation of the bottom plate is effectively controlled, achieving good deformation control effect of high stress soft rock roadway.

Aiming at the problems of soft coal seam, low permeability, high gas content, difficult long-distance drilling along the seam and poor drainage effect in Yangquan mining area, taking Huayang No.2 Mine as a demonstration mine, based on the analysis of mine gas geology and drainage treatment status, the overall scheme of gas drainage drilling construction using high-power nitrogen directional drilling technology and equipment is proposed. The technical principle and technical advantages are introduced, and the key technologies of nitrogen directional drilling, such as composite directional trajectory control technology, composite high-efficiency slag discharge technology, long-distance drilling along the seam, and long-distance sieve tube hole protection technology for directional drilling, are developed. The core equipment of high-power directional drilling equipment, such as high-power directional drilling rig, nitrogen making device, high-torque and long-life pneumatic screw motor, was studied and selected. The overall test scheme of drilling field design, drilling design, equipment matching and drilling tool combination design was formulated. The high-power nitrogen directional drilling test of bedding drilling was carried out in the 81511 drilling field of Huayang No.2 Coal Mine. According to the test results, the high-power nitrogen directional drilling technology and equipment can realize the efficient directional drilling and gas drainage in the soft and low permeability coal seam. The construction completed 7 main holes and 13 branch holes of directional drilling, of which 5 holes were more than 350 m deep, the maximum hole depth reached 506 m, and the total footage was 3363 m. The diameter of the drilling hole is 120 mm, and the Φ32 mm sieve tube is put into the whole hole. The test drilling field has been stably extracted for nearly half a year, the gas extraction concentration has exceeded 50 %, the gas extraction purity has reached 2.46 m3/min, and the cumulative gas extraction purity has reached 56.06 million m3. It provides a new technical way for the efficient extraction and control of gas area in broken soft and low permeability coal seam of Yangquan mining area, which can be used for reference in mines with similar conditions.

Thick bedrock working face is prone to produce the phenomenon of large overhanging area of the arc-shaped triangle at the end of the working face during the mining period, which is prone to produce the accident of large-area coming pressure on the roof plate and affects the safe production of coal mines. In order to analyze the mechanism and evolution law of the formation of the arc-shaped triangle at the end of the working face, we take the working face of 12407 of Huangyuichuan Coal Mine as the research background and focus on the problem of large overhanging area of the arc-shaped triangle at the end of the working face during the mining process in the gum transporting and wind-returning chutes, through the combination of theoretical analysis, laboratory test and numerical simulation. In order to solve the problem of large overhanging roof area in the working face of 12407 working face, through theoretical analysis, laboratory test and numerical simulation, we analyzed the formation mechanism of 12407 working face arc triangle, studied the evolution law of 12407 working face arc triangle in the process of mining, and put forward the management plan of large overhanging roof area in 12407 working face arc triangle of Huangyuchuan Coal Mine. Research results show that: due to the roof plate "O-X" broken, the roof plate rock strength is larger, the working face two ends of the location of the hard roof plate is difficult to collapse, easy to produce the working face roof end of a large area of overhanging, the formation of the end of the arc-shaped triangle, theoretical calculations of the Huangyuchuan coal mine 12407 working face end of the arc-shaped triangle Theoretical calculation shows that the overhanging distance of the triangle is 20.1m; by analyzing the damage characteristics of the roof plate in the air-mining area during the advancement of the working face, it is concluded that with the advancement of the working face, the geometrical form of the working face's end arc-shaped triangle is gradually reduced, but the magnitude of the reduction is relatively small, and there is still a safety hazard of the end-end large-scale overhanging roof, and the Huangyu-Chuan coal mine 12407 working face's end-end arc-shaped triangle management plan is proposed to manage the overhanging roof in the field. Along the parallel direction of the working face from the original 20m reduced to 5.3m, along the vertical direction of the working face from the original 15m reduced to 6m.

Addressing the issue of difficulty in achieving large-scale pre-relief of rock burst in working faces under thick hard roofs, a study was conducted on hydraulic fracturing technology in long boreholes for rock burst prevention at the 20101 face of Dazezhe Coal Mine. Using theoretical analysis and field measurements, the fracturing layers were identified, and the effects of hydraulic fracturing and rock burst prevention were evaluated. The conclusions are as follows: ①By analyzing the height of the caving zone filled with rocks in the goaf and the distribution pattern of microseismic events in the working face, and comprehensively considering the height required to fill the goaf, the fracture range of the overlying strata, and avoiding damage to the existing roadway support structures during fracturing, the design heights for underground long borehole hydraulic fracturing were determined to be 20 meters and 35 meters, respectively. ②During fracturing, the water pressure fluctuates within a stable range, and in the late stage of fracturing, the sudden increase in water output from adjacent boreholes indicates that the fractures in the target layer have communicated with adjacent boreholes, forming a fracture network, demonstrating good fracturing results. ③After adopting underground long borehole hydraulic fracturing, the total energy and frequency of microseismic events, high-energy microseismic events, dynamic load coefficient, and pressure step distance significantly decreased or reduced. The research results indicate that underground long borehole hydraulic fracturing can significantly reduce the risk of rock burst in the working face, achieve safe mining under thick hard roofs, and provide a reference for rock burst prevention in working faces of mines with similar geological conditions.

As high gas mines gradually enter the realm of deep mining, the problem of rockburst has become increasingly prominent. In response to the problem of rockburst in high gas mines, the technology of anti- punching pressure relief by gas extraction borehole along stratum in gas mine is discussed. The research results indicate the followings. Extraction drilling can reduce the stress environment of coal. However, the pressure relief effect of gas drainage drilling is slightly weaker than that of large-diameter pressure relief drilling. By utilizing the lateral stress zoning characteristics of the surrounding rock of the roadway, improved sealing process of extraction and pressure relief drilling, the sealing section of the borehole is transformed from a single section sealing to a double section sealing. The extraction and pressure relief technology was established, and further applied to the high gas mine walking face. Field test results show the followings. After the construction of extraction and pressure relief drilling, the average maximum energy of microseismic events decreased by 4000J, the average daily energy decreased by 1000J, which indicated that the roof activity was significantly weakened. The displacement of the two sides was reduced by 300mm, the proximity of the top and bottom was reduced by 100mm, which indicated that the deformation of the roadway surrounding rock is obviously improved. This indicates that sequential drilling can achieve the pressure relief effect of the coal seam in the mining space, while also taking into account the functions of gas extraction and pressure relief from rock burst, truly achieving the dual use of one hole.

In this paper, comprehensive research methods such as laboratory experiments, theoretical analysis, numerical simulation and field measurements are used to systematically study the development characteristics of mining fractures and water hazards in the overlying rock of the small coal pillar working face. According to the empirical formula of the conduction height and the measured results, it is clear that the range of the crack-to-production ratio of the working face is 21~27, and the maximum development height of the water conduction fracture zone is 117 m. Combined with numerical simulation, the characteristics of the saddle-shaped distribution of the water conduction fracture zone in the working face were clarified, and the development characteristics of the water conduction fracture zone under different mining parameters such as coal pillar width, working face length and mining thickness were mastered. Based on the ArcGIS platform, it is clarified that the key prevention and control areas of water hazard on the roof of the working face are 1041 m~2411 m and 3299 m~4630 m away from the cutting eye of the working face. Combined with the risk zoning of roof water hazard, a technical scheme of "exploration-release" of water hazard between the roof of the working face and the goaf of the upper section was proposed. Key words: Narrow coal pillars; water-conduction fracture zone; Risk Zoning; Water Hazard Control

In order to solve the problem of poor dust suppression effect of airborne external spray dust suppression system in the driving face of the 31 coal mine auxiliary transportation mountain half coal rock roadway in Daliuta Mine, which can not adapt to the coal dust and rock dust control during the tunneling process, based on the coal dust and rock dust samples collected at the working face site, an experimental study on the dust wetting characteristics of the composite surfactant was carried out, and the best surfactant composite scheme and proportion were obtained. Through the composite surfactant spray dust suppression test and the tunneling simulation test, the best spray pressure test of the roadway was carried out to verify the dust suppression efficiency improvement effect of the spray dust suppression system after adding the composite surfactant on the coal dust and rock dust samples collected at the working face, and the best spray pressure was determined Parameters. The field application results show that the dust concentration in the coal and rock mass excavation process of the working face is effectively reduced after adding the compound surfactant to the water used in the spray system of the working face, and the dust concentration at the driver's position and the 15m position at the downwind side is 486.27 mg/m3and 279.33 mg/m3Reduced to 180.20 mg/m3and 116.80 mg/m3. In the process of tunneling, the total dust reduction efficiency of coal dust reached 62.94% and 58.19%, respectively.

Given the unclear scope and lack of basic data on the small kiln destruction area caused by room-pillar mining in Guojiawan Coal Mine, a method combining geophysical exploration, drilling, and three-dimensional spatial scanning technology was used to conduct a detailed exploration of the goaf area, roof status and water accumulation, internal tunnels, and coal pillar size. First, the goaf area and different partitions were delineated by interpreting the abnormal area through ground transient electromagnetic physical properties and verifying the exploration results through drilling. Then, the three-dimensional spatial scanning technology was used to conduct detailed scanning and observation of the internal space of the water and water-free goaf areas, and high-precision technical data such as tunnel width, goaf height, coal pillar size within a certain range around the bottom of the borehole were obtained. The internal and external morphology of the goaf was obtained through three-dimensional modeling. The research method in this paper can provide support for the exploration of small kiln destruction areas, accurate data measurement of internal space, stability assessment of goaf areas, and disaster prevention.

In order to study the mine pressure manifestation and surface settlement law induced by 8-meter super-high working face mining, the study means of arranging stress monitoring system in the underground working face of 2203 working face of Zhangjiamao Coal Mine of Shaanxi Coal Group and arranging GNSS automatic observatory in the surface were used to collaboratively analyze the mine pressure manifestation law and surface settlement characteristics during the period of mining of this working face. The mine pressure at the 8-meter super-large mining height of the 2203 working face exhibits distinct regional pressure, with a pattern of "higher in the middle and lower at both ends" in the working resistance of the support. Compared to ordinary mining heights, the larger mining space and the increased load from the roof in super-large mining faces result in greater pressure on the support, leading to more severe mine pressure. The periodic pressure cycles in super-large mining faces are generally longer, with high pressure intensity, following a pattern of alternating large and small cycles. When the super-large mining face experiences pressure, the support resistance increases sharply, with a significant amplitude of resistance growth. 8m super high 2203 working face has a shorter active period of surface subsidence, and the sinking speed is bigger during the period, and the surface subsidence is violent, but the recession period is longer; the influence range of the surface subsidence induced by the mining back of the working face is bigger, but the area of significant subsidence is smaller, and the basin formed by the subsidence is in the shape of an "inverted straw hat"; The surface cracks are obviously developed, with large widths, mainly in the middle of the working face's hollow area, distributed in a non-closed ring, and the surface of the whole working face is seriously damaged, forming obvious step-like cracks; the amount and scope of surface settlement caused by the mining back of the oversized working face are larger, and the rate of subsidence is faster and lasts for a longer time than that of the ordinary working face.8 The surface of 2203 working face of 8m super high mining height will come to pressure in 1~5d before the settlement, which shows that the mine pressure will show on the surface settlement has a warning effect, and then with the cycle of coming to pressure, the surface settlement goes through the slow settlement, rapid settlement stage and settlement stabilization stage, the rapid settlement stage is more frequent than the slow settlement and settlement stabilization stage of the downhole mine pressure shows more frequently and violently, the number of times of coming to pressure increases, the step distance of coming to pressure decreases, the downward speed of settlement is faster, and the duration is longer. The number of incoming pressures increases, the step size of incoming pressures decreases, the duration of incoming pressures increases, and the faster the working face advances, the greater the subsidence rate of the ground surface;. The research results provide technical support for this working face and the subsequent similar working faces.

Abstract: Clarifying the movement laws of the overlying rock strata under repeated mining activities at extremely close range is of great significance for the stability of the mining field and the control of the surrounding rock in the return mining roadways. In the eastern mining areas, the situation of mining coal seams at close range is common, and strong mining pressure phenomena often occur in the underlying return mining roadways when the mining face is arranged in such coal seams. To further study the movement laws of the overlying rock strata under repeated mining activities at extremely close range, taking the extremely close range mining face of the Fucun Coal Mine in Zaozhuang Mining Area as the engineering background, a combination of theoretical derivation, numerical simulation, and on-site measurement was used to analyze the mining of various working faces of the 3rd upper and 3rd lower coal seams in Fucun Coal Mine and the overlying rock strata affected by repeated mining activities, as well as the state and evolutionary characteristics of the overlying rock movement. The results show that, according to the key layer theory calculation, the fracture distance of the key layer of the overlying rock of the working face is positively correlated with its distance from the top of the coal seam, and negatively correlated with the face width, and the fracture distance of the key layer decreases significantly after the second disturbance, with the percentage decrease being positively correlated with the face width. It is calculated that the height of the repeated mining fracture zone of the 1009 working face in the 3rd lower section is 94.7 m. According to the UDEC numerical simulation results, the secondary movement of the overlying rock caused by repeated mining activities greatly increases the range of the fracture zone, and the range of the fracture zone increases significantly with the increase of the working face width. It is concluded that the height of the caving zone and the fracture zone of the 1009 working face in the 3rd lower section are 32.4 m and 91.8 m, respectively. On-site measurement of the height of the two zones of the overlying rock was conducted using double-end water plugging devices, and the height of the caving zone and the fracture zone of the 1009 working face in the 3rd lower section were obtained as 41.43 m and 101.03 m, respectively, corroborating the results of theoretical derivation and numerical simulation. The research results can provide corresponding theoretical and technical basis for theoretical research and engineering construction under similar conditions.

To investigate the influence of pressure on the atomization characteristics and dust suppression efficiency of internal-mixing nozzles, experiments were conducted using a custom-built spray dust suppression platform. The study examined the atomization behavior and dust suppression efficiency within the pressure range of 0.15 MPa to 0.4 MPa for both air and water, aiming to elucidate the mechanisms by which two-phase fluid pressure affects nozzle flow rate, atomization angle, droplet size, and dust suppression performance. The results demonstrate that, under constant water pressure, as air pressure increases, air consumption rises almost linearly, while water consumption decreases exponentially. The atomization angle progressively narrows, and the droplet size metrics decline accordingly. When air pressure is further elevated, the rate of droplet size reduction diminishes, and the droplet size distribution becomes more concentrated. As air pressure increases from 0.15 MPa to 0.4 MPa, air consumption increases by 47.5 L/min, water consumption decreases by 0.61 L/min (a reduction of approximately 83.56%), the atomization angle reduces by 38°, and D[3,2] decreases by about 54 μm. Under constant air pressure, increasing water pressure reduces air flow and increases water flow, leading to a widening of the atomization angle. However, further increases in water pressure weaken the gas-liquid interaction, causing the atomization angle to decrease once more. The droplet size distribution broadens, and the frequency peak shifts downward. When water pressure rises from 0.15 MPa to 0.4 MPa, air flow decreases by 10.2 L/min, water flow increases by 0.94 L/min, the atomization angle increases by 16°, and D[3,2] increases by approximately 31 μm. Increases in either air or water pressure result in an initial rise followed by a decline in dust suppression efficiency for both total and respirable dust. Based on an analysis of the effects of pressure on nozzle flow rate, atomization angle, and droplet size, the optimal combination of water and air pressures was identified as PL = 0.3 MPa and Pair = 0.25 MPa. Under these conditions, the dust suppression efficiency for total dust and respirable dust reached 71.99% and 45.96%, respectively.

In order to study the key factors affecting the water richness condition of the Jurassic coal seam roof and make a reasonable evaluation of the water richness condition of the Jurassic coal seam roof, this paper uses GeoDetector to explore the connection between the lithological and tectonic factors and the interactions between the factors and the water richness, to screen out the main factors affecting the water richness and to evaluate the level of water richness of the study area by using the Shaozhai Mine as an example, using the AdaBoost algorithm. The results show that the number of sand and mud interbedded layers (0.62), sandstone equivalent thickness (0.45), sandstone thickness (0.42), sand to mud ratio (0.31) and lithological influence index (0.09) are the key factors for the evaluation of water richness in the study area, in which the number of sand and mud interbedded layers is the most important factor for the evaluation of water richness of the roof of the Jurassic coal seam, and the tectonic factors have weaker influence on the water richness condition of the Jurassic coal seam. The areas with high water richness in the study area mainly exist in the northeast, the areas with medium water richness are in the west-central and a small part of the east-central part of the study area, and the majority of the study area has low water richness. The GeoDetector can determine the main factors affecting the water richness of the Jurassic coal seam roof, and combined with the AdaBoost algorithm, it can reasonably evaluate the water richness of the Jurassic coal seam roof.

In recent years, water inrush from bed separation in coal mines occurs frequently, and the disaster of water inrush in the bed separation is gradually receiving attention. Due to the inrush of bed separation water in overlying strata has characteristics of without obvious precursor and gushing rapidly, it is likely to cause accidents if there is no forecast or handled improperly. Based on the study area of 104 and 106 mining area in Yangliu coal mine of Huaibei Mining Group, the paper determined five main factors that influenced the inrush of water in bed separation by the analysis, then build the geological model to forecast the inrush of water in bed separation by using analytic hierarchy process and modeling capabilities of GIS, and tested the reliability of the model, the results of test are ideal. This research result can directly serve the safe mining of coal seams in the research area and similar mining areas, and also enrich the theory of prevention and control of water inrush from bed separation.

Aiming at the problems that single-phase grounding fault line selection of mine power grid is greatly interfered by underground environment, and the fault line selection speed and accuracy are low, A new method for single-phase grounding fault line selection of mine power grid based on arithmetic optimization algorithm and improved continuous variational mode decomposition and attention mechanism convolutional neural network is proposed. Firstly, the parameters of continuous variational mode decomposition are optimized by arithmetic optimization algorithm, and the zero-sequence current sequence is divided into natural mode functions of different frequencies. Secondly, the data preprocessing method of relative position matrix is introduced to convert one-dimensional sequence into two-dimensional image, and the time-frequency characteristic diagram of zero-sequence current signal is obtained. Finally, the attention mechanism is embedded into the CNN classification algorithm model to realize fault line selection.. The simulation and experimental results show that the proposed method can accurately select fault lines under the conditions of strong noise and asynchronism of sampling time, and can meet the requirements of accuracy and reliability of line selection in mine power grid.

In the operation process of the toothed roller crusher, the crushing teeth, as the direct force bearing components, continuously bear strong forces such as impact and compression applied by the material, making them the most vulnerable components to wear and tear. The condition of these broken teeth directly affects the overall working efficiency and performance of the toothed roller crusher. At present, the application scenarios of toothed roller crushers are becoming increasingly complex and diverse, such as underground mines that are not suitable for replacement and maintenance, and open-pit coal mines with a large processing capacity, which pose great challenges to the performance and convenience of crushing teeth. Therefore, a replaceable crushing tooth is designed, and the Discrete Element Method (DEM) is used as the research method to explore the crushing effect of replaceable crushing teeth in the crushing process. Meanwhile, in order to evaluate the load-bearing capacity of replaceable broken teeth, further strength analysis was conducted using finite element method (FEM).This can optimize the design of the crushing tooth structure.

Machine vision has been widely used in the field of coal processing and sorting. However, in image segmentation, there are still challenges in separating the background and foreground in multi-scale feature coal particle CT images, as well as segmentation challenges caused by inconsistent particle sizes. This paper proposes a semantic segmentation method for coal particle CT images based on an improved ECA-Segformer model. In order to address the phenomenon of missed detection that occurs due to uneven distribution of particles at multiple scales, the model introduces the ECA-Net attention mechanism to effectively enhance the network's representation ability, aiming to improve segmentation accuracy. In addition, the use of the Squared ReLU activation function can better capture the different features of the foreground and background, thereby improving the segmentation efficiency of coal particle CT images. Experiments were conducted using a self-built CT dataset of coal particles. The results showed that the improved Segformer model had the best comprehensive detection ability, with an average intersection-union ratio of 87.78%, an average pixel accuracy of 93.44%, and an accuracy rate of 93.46%. Compared to the basic Segformer network, it improved by 2.12%, 1.30%, and 0.58% respectively. The analysis of the segmented data can study the particle size distribution statistics of coal particles, which is of great significance for efficient and intelligent separation of coal.

In response to the complex issue regarding the influence of the liberation degree and particle size of pyrite in high-sulfur coal gangue on the sulfur recovery process through gravity separation, test and experimental methods such as the AMICS automatic quantitative analysis system, X-ray fluorescence spectrometer, and shaking table experiments, combined with the kinetic analysis of the shaking table separation process, were employed. The technological mineralogy characteristics of high-sulfur coal gangue and the influence of the liberation degree of pyrite in high-sulfur coal gangue on the migration law of gravity separation products were investigated. The results indicated that the ratio of pyrite to the total sulfur content in high sulfur coal gangue was as high as 87.16%, and pyrite was mostly associated with kaolinite in forms such as tabular, group aggregations, or lumps. When recovering pyrite from high-sulfur coal gangue using the shaking table, the lower limit of the effective separation particle size was 0.038 mm. The liberation of pyrite in the concentrate after separation was favorable, with a single liberation degree reaching as high as 82.37%. However, the pyrite in the re-election and roughing tailings had a more complex associated relationship with other minerals, and the single liberation degree of pyrite was relatively low. Meanwhile, the particle size and single liberation degree of coal gangue had a significant influence on their movement trajectories on the shaking table bed surface. When the single liberation degree of pyrite was lower than 85%, it would cause pyrite to be lost in the tailings to varying degrees.experiments, combined with the kinetic analysis of the shaking table separation process, were employed. The technological mineralogy characteristics of high-sulfur coal gangue and the influence of the dissociation degree of pyrite in high-sulfur coal gangue on the migration law of heavy separation products were investigated. The results indicated that the ratio of pyrite to the total sulfur content in high-sulfur coal gangue was as high as 87.16%, and pyrite was mostly associated with kaolinite in forms such as tabular, group aggregations, or lumps. When recovering pyrite from high-sulfur coal gangue using the shaking table, the lower limit of the effective separation particle size was 0.038 mm. The dissociation of pyrite in the concentrate after separation was favorable, with a single dissociation degree reaching as high as 82.37%. However, the pyrite in the re-election tailings and roughing tailings had a more complex associated relationship with other minerals, and the single dissociation degree of pyrite was relatively low. Meanwhile, the particle size and single dissociation degree of coal gangue had a significant influence on their movement trajectories on the shaking table bed surface. When the single dissociation degree of pyrite was lower than 85%, it would cause pyrite to be lost in the tailings to varying degrees.

Improving the industrial carbon emission efficiency in regions where coal is the main resource can reduce the reliance on fossil energy, promote the clean and efficient utilization of coal and the development and utilization of renewable energy, and is one of the important ways to achieve economic low-carbon transformation and regional sustainable development. Quantifying the industrial carbon emission efficiency and its influencing factors in coal-dominated regions is a necessary prerequisite for achieving efficiency improvement. This study selected a certain province in the central region and several coal-dominated cities and prefectures under its jurisdiction as the research samples. Data enveloping analysis was used to evaluate the carbon emission efficiency and trend, and the Tobit regression model was utilized to deeply explore the key influencing factors of carbon emission efficiency. Research has found that although the energy structure dominated by coal has a strong inhibitory effect on carbon emission efficiency, the overall carbon emission efficiency of industrial scale and above in China's coal-dominated regions still shows an upward trend. The scale effect can reduce the carbon emissions per unit output and have a positive impact on carbon emission efficiency. In addition, promoting the low-carbon transformation of the energy structure, accelerating the upgrading of the industrial structure, and expanding the scale of enterprises all contribute to enhancing the industrial carbon emission efficiency in coal-dominated regions.

As an important hub connecting the cutting arm and the body of the roadheader, the dynamic characteristics and reliability of the rotary table are the key to improve the cutting speed. In this paper, the dynamic characteristics and structural optimisation of the rotary table are studied, the explicit dynamic model of the cutter tooth cutting hard rock is established to obtain the cutting load force; the rigid-flexible coupling model of the whole machine is constructed, and the dynamic characteristics of the rotary table under different working inclination angles are studied; the structural bionic optimisation of the rotary table is carried out by referring to the structure of the human femur. The results show that the roadheader is the most stable when cutting in the downward direction, and the stability of the machine body will be affected if the cutting arm is lifted too high. The force on the upper articulated hole of the rotary table is the main reason affecting its dynamic characteristics. The upper articulated hole mainly bears the support force during cutting, and the lower articulated hole mainly bears the normal force of the coal rock plane. The equivalent force of the optimised rotary table is reduced by 33.072% and the deformation is reduced by 2.122%. This study is of great significance to the rapid boring and optimised design of roadheader.