Abstract: In China’s western coal mines, shafts need pass through deep, water-rich, weakly cemented surrounding rock for-mations from Cretaceous and Jurassic periods. Artificial ground freezing methods are applied during the construction of large-diameter shafts. Determining the appropriate frozen depth is crucial for safe and successful shaft lining construction. In the case of deep shaft freezing, the cost of freezing significantly increases with depth. To rationally determine the shaft lining's frozen depth, the factors influencing frozen depth are analyzed, and a comprehensive assessment based on two main factors: the loca-tion and dimensions of shaft-related chambers and the geological conditions of the shaft (including engineering and hydrogeo-logical conditions) are proposed. By combining specific analyses of shaft-related chambers, rock distribution patterns, and wa-ter content in the main and auxiliary shafts of a particular mine, along with insights from neighboring mine shaft construction experiences, an optimized frozen depth plan for the shaft lining are proposed. The advantages and disadvantages are analyzed, and a technical and economic comparison are performed. The research methodology can provide as a technical reference for determining shaft lining frozen depths under similar geological conditions.

In response to the current mining situation of the Hongshaquan open-pit coal mine, it was found that the angle of the end slope is generally lower than the design requirements, which makes it difficult to effectively exploit the overlying coal resources and leads to the waste of coal resources. This study used the Morgenstern-Price limit equilibrium method and finite element strength reduction method to analyze the ultimate angle and sliding mode of the western slope, and verified the feasibility of improving the end slope angle through steep slope mining; Based on the three-dimensional numerical simulation of the mining site, explore the influence of different tracking distances and working slope angles on the stability and deformation of the end slope under the influence of the internal dumping site and working slope; Based on comprehensive engineering conditions, two end slope and steep slope mining schemes were analyzed and compared. The results show that the maximum angle of the western slope can be set at 36°, which is suitable for implementing steep slope mining to optimize the angle of the end slope; Under the influence of the internal dumping site and the working slope, the tracking distance has a significant impact on the deformation and stability of the slope. As the tracking distance increases, the deformation amount and range of the deep rock mass gradually increase, but the gradient of change is small; The change in working angle has a relatively small impact on the stability of the end slope. As the working angle of the slope increases, the exposed area of the end slope surface decreases, and the stability of the end slope increases; Considering the impact of the crushing station on the western slope, a combination of reducing the width of the flat plate and merging steps was adopted to determine the steep slope mining plan. After optimization, the overall angle of the western slope was 18°, with an average annual increase of 800000 tons of raw coal recovery, a stripping ratio of 1.5 m3/t, and an economic benefit of 96.7 million yuan.

Due to lack of reference, parameter value of wind load shape coefficient and gust response coefficient becomes a design problem for closed belt machine conveyor bridge. Taking the coal and ore conveying project of the wharf in Indonesia as an example, compared with the relevant provisions of Chinese, American and European codes, 3D model analysis was carried out by using MIDAS finite element software. The results show that shape coefficients of conveyor bridge or semblable structure are similar in different countries’ codes. Wind load shape coefficient is affected by wind direction angle. There may be a wind pressure concentration area at the end of conveyor bridge. The force and deformation of conveyor bridge need to be considered by this influence factor. The stress of trestle support under the action of uneven wind load needs to be paid attention to.

In order to optimize the effect of rainwater storage in coal mine industrial site under different rainfall conditions, a method of rainwater storage in coal mine industrial site based on SWMM model was proposed. The overflow calculation method for rainwater storage tanks based on the SWMM model is used to calculate the overflow in the catchment area and pipeline network of coal mine industrial sites during rainfall. Based on the optimization model of rainwater storage tanks and focusing on the overflow situation of rainwater storage tanks in the factory area, an objective function and constraint conditions for optimizing rainwater storage tanks are established. Non dominated sorting genetic algorithm is used to obtain the optimal drainage scheme of rainwater storage tanks and achieve reasonable rainwater storage in coal mine industrial sites. The research results indicate that this method can reduce underground seepage losses and surface runoff in coal mining industrial sites at different recurrence periods, and improve the external discharge of the factory area and the storage capacity of rainwater storage tanks. Among different types of rainfall, the water depth and flow rate at the outlet of the rainwater storage tank can be reduced. In different rainfall times, the number of overflow nodes, overflow time, and overflow depth can be reduced

Abstract: Aimed at the problem of safe rotary mining of protective coal pillars in the lower roadway of adjacent chamber group in 2317 working face of a Coal Mine in Jining affected by multiple disturbances. Employ theoretical analysis, numerical simulation and field monitoring, the distribution law and influence range of mine pressure in rotary fully mechanized mining face are 68 m. The research results show that: the mining stress concentration in the central area of rotary mining and the repeated support of triangular arc suspension plate by hydraulic support, the stress concentration at the near end of the working face is significantly higher than that at the far end; Under the influence of mining activities, the cave system experiences deformation and destruction, and the overburden stress is relieved, forming a ' mining stress release zone '. In this regard, a support scheme combining cable netting and W steel plates was proposed and implemented during the rotary mining process, the advance tunnel is reinforced with U-shaped steel sheds and unit supports. On-site monitoring showed that the support scheme had good control over the mining pressure caused by rotary mining, and the working face could be mined safely.

Utilizing the 5-2 coal seam working face in the first mining district of Guojiawan Coal Mine as an engineering backdrop, the analysis was conducted on the issue of designing a zonal support method for overlying obliquely intersected coal pillar roadways, which is based on the thickness of unstable strata. Through the application of theoretical analysis, numerical simulations, and on-site engineering practices, the study was conducted to investigate the mechanical structure of surrounding rock and the stability of roadways beneath the remaining obliquely intersected coal pillars. This led to the determination of the principles for designing support zoning and the preferred parameters for support, both of which are based on the thickness of intact rock strata. Besides, through field engineering practices, a zoning support plan for the roadway was determined and subsequently simulated for verification. The research findings indicated that when conditions such as the mining height and stress concentration factor at the upper coal seam working face changed, the thickness of the unstable rock stratum also varied accordingly, displaying a positive correlation. Among these factors, the stress concentration factor had a relatively significant impact on it. As the interlayer spacing decreased and approached the centerline of the coal pillar, the stress concentration factor continually increased, while the distance between supports and the effective length of the roof bolt decreased accordingly. In such circumstances, the support scheme was successively adopted with bolt-cable, full-cable, and shed support. The numerical simulation proved to be feasible and practical, and the field verification demonstrated good control effects. This provided a theoretical basis for studying the support issues of roadways located beneath overlying oblique coal pillars.

In order to ensure the safety of the 8306 isolated island working face under pressure mining in a certain mine of Shuo Coal Company, and to clarify the degree of influence of Ordovician limestone water on the mining of the 8306 working face.Comprehensive geophysical exploration was conducted on the structure and water abundance of the working face floor using transient electromagnetic method, audio electric perspective method, and radio wave perspective method. The water abundance and structural development of the working face floor were identified, and analyzing the safety of mining under pressure in 8306 working face based on geophysical exploration results. The results indicate that there is a limestone wall with almost no intrusion of water-bearing magmatic rock in the coal seam of 8306 working face, and several generally weak fissure water or low resistance rock masses are inferred within a range of 40m from the bottom plate. Among them, one fault is inferred in the southeast region to connect with the water-bearing body of Ordovician limestone water, and the Ordovician limestone aquifer below 40m from the bottom plate is inferred to have strong water-bearing ability - generally Ordovician limestone water;During the normal pressure mining process of 8306 working face, water inrush generally does not occur. However, if there is a hidden penetrating water conducting structure in the section, especially in the area where the water bearing body and structure overlap delineated by mine geophysical exploration, there may be a risk of water inrush from the coal seam floor.Water prevention and control work such as drilling and hydrological monitoring and warning should be done well.

The mining of Group A coal in Pan 'er Coal Mine in Huainan Mining area is seriously threatened by the high confined water of floor. In order to clearly understand the depth and development mechanism of floor failure in Group A coal mining process, based on FLAC3D numerical simulation and microseismic monitoring technology, the stress distribution and floor failure range of Group A coal mining face under mining disturbance were analyzed. According to the real-time monitoring data of microseismic in the process of mining, the cluster analysis of floor crushing concentration range is made by SPSS software. The research results show that the concentrated depth of floor failure zone is 23~30m, and the average floor failure depth is about 27m. In the floor fractured rock mass of the lower stratified mining face, there is a large concentration in the floor depth of 9~22m, and it is highly concentrated at 21m below the floor. The floor fractured body induced by the lower stratified mining is basically within the failure range of the upper layer coal seam mining floor, and the mining failure zone and the water-bearing guide zone are not connected

Aiming at the problem of gas extraction and spontaneous combustion of residual coal in goaf of fully mechanized caving face in spontaneous combustion coal seam, taking 150315 fully mechanized caving face of a mine in Shanxi as an example, the distribution characteristics of cracks and porosity in goaf of this working face are analyzed by theoretical calculation and numerical analysis, and the reasonable horizon of high drainage roadway is given from the perspective of gas extraction. Based on Comsol simulation, the distribution characteristics of gas concentration and spontaneous combustion ' three zones ' in goaf under the disturbance of high drainage roadway at different positions are compared and analyzed, as well as the quantitative variation characteristics of gas concentration and oxygen concentration under different negative pressure of extraction. It is pointed out that the horizontal distance is positively correlated with its disturbance effect on ' three zones ', and its vertical height is proportional to the concentration of extracted gas and inversely proportional to the concentration of extracted oxygen. It is determined that the horizontal position of high drainage roadway is 20 m away from the return airway, the vertical height is 50 m, and the reasonable negative pressure is 20 kPa, which is verified by field practice. After optimization, the extraction amount of high drainage roadway and the gas concentration in the upper corner of the working face are within the safe range. At the same time, the width of spontaneous combustion oxidation zone in goaf is reduced, the risk of spontaneous combustion is effectively reduced, and the cooperative co-governance of gas and coal spontaneous combustion in goaf is realized.

Abstract: In recent years, the phenomenon of CO exceeding the limit in the return air corner of the working face in Shendong mining area has become more and more serious, which seriously affects the safety production of coal mining enterprises. Therefore, taking 104-1 comprehensive mining face on 22 of Ohtai coal mine as the research object, a series of experiments were carried out, such as CO test of primary endowment in coal seams, test of CO production rate of coal at room temperature, test of CO production in the process of coal mining, and test of CO produced by exhaust gas of underground rubber wheel trucks, to investigate the main source of CO in the return air corner of comprehensive mining face. The study shows that about 75% of the CO is generated from the normal temperature oxidation of floating coal, 13% and 12% are generated from the coal cutter and the tail gas of rubber wheel trucks, and the primary CO in the coal seam is almost 0. The CO in the return air corner of the comprehensive mining face mainly comes from the oxidation of floating coal in the mining air space. By studying the source of CO, measures such as equal-pressure ventilation and spraying inhibitor were proposed to reduce the CO concentration in the return-air corner from 42 ppm to less than 10 ppm by reducing the oxidation of floating coal inside the air-mining area and preventing the leakage of CO in the air-mining area, which solved the problem of CO exceeding the limitation at the working face, and effectively ensured the safety production of theShi Ohtai Coal Mine.

In order to solve the problems of low concentrate yield and high ash content of concentrate which can not reach the qualified quality requirements (ash content of concentrate <12%) by conventional flotation process for Longquan 4# floating slime, the multi-stage flotation process was explored. The "one rougher, one cleaner" two-stage flotation tests revealed that the entrainment of high-ash fine slimes led to elevated ash content in the concentrate. Due to the high-shear flocculation flotation demonstrated a significant improvement in reducing fine slime entrainment, the "high-shear flocculation flotation +one rougher , two cleaner" flotation process combined with a reasonable flotation reagent system was adopted. The mechanisms underlying the improvement in flotation efficiency due to high-shear flocculation were analyzed using laser particle size analyzer, contact angle measuring instrument, scanning electron microscopy, and calculations of the collision probability between coal particles and oil droplets. The results indicated that using the flotation process of " high-shear flocculation flotation +one rougher, two cleaner ", the concentrate ash content of Longquan 4# difficult-to-floate coking slime can be reduced to 11.73%, the concentrate recovery rate reached approximately 50%, and the tail coal ash content can be increased to 82.57%. Both the concentrate and the tail coal index can meet the requirements of coal preparation plant.

In view of the increasingly stringent discharge requirements of coal mine water, this paper systematically evaluates the removal effect of traditional mine water purification technology on dissolved pollutants by using the existing purification process of a coal mine in southwest Shanxi. The results show that the mine water can not only effectively remove high-concentration particulate matter, but also remove dissolved pollution components such as organic matter, total phosphorus, fluoride, sulfide and total mercury to varying degrees. The enhanced purification measures of activated carbon adsorption and microfiltration can ensure that all dissolved pollutants except total nitrogen and fluoride can stably meet the Class III standard of surface water in the environment of large fluctuations in the concentration of pollutants in the raw water of the mine. Further studies found that the adsorption of particulate matter and activated carbon in mine water and the mechanical retention of microfiltration membranes were the mechanisms for the purification and removal of dissolved pollutants. In order to improve the purification effect of total nitrogen and fluoride, it is suggested to add denitrification denitrification unit and fluoride adsorption unit on the basis of the existing treatment process, which can provide theoretical support for the selection and upgrading of coal mine water purification process.

The stability control of the floor is the basis of the stability control of the ' support-surrounding rock ' system in steeply inclined coal seam mining. Based on the engineering background of a steeply inclined long-wall fully mechanized mining face in a mine, this paper adopts the research method of combining physical similarity simulation and numerical calculation. On the basis of comprehensively determining and analyzing the general law of asymmetric deformation and failure of floor, the transmission path of floor mining stress and its dip angle effect are studied, and the evolution characteristics of principal stress gradient and direction deflection of floor in steeply inclined stope are quantitatively characterized. The results show that in steeply inclined coal seam mining, the transmission path of mining-induced stress in the floor exhibits an asymmetric anticlinal shape under the influence of the coal seam dip angle. Within the stress arch, the immediate floor and the basic floor in the middle-lower region of the working face are under tensile stress, with the principal stress direction nearly parallel to the coal seam. Outside the stress arch, the principal stress in the floor deviates toward both sides of the coal body, with the stress deflection boundary serving as the demarcation line. Furthermore, as the coal seam dip angle increases, the arch height of the floor stress arch and the support pressure on the lower side of the working face floor exhibit a decrease-increase-decrease trend. The magnitude of the first principal stress and the unloading coefficient gradually decrease, with the maximum unloading position migrating toward the coal body on the lower side of the working face. The direction of the first principal stress gradually deflects towards the coal seam, resulting in a gradual reduction in the depth of floor failure. As a result, the maximum failure depth of the floor is located in the middle-lower region of the working face. Meanwhile, influenced by the unequal confinement effect of the goaf's waste rock, the floor block structure in the middle-upper region of the working face is more prone to instability and sliding, with upward expansion likely under continued mining disturbance. Based on these findings, targeted preventive measures such as "key monitoring and regional treatment" can be implemented in areas prone to failure and sliding. These measures aim to improve the stress environment and structural characteristics of the floor in these regions, thereby achieving effective stability control of the floor in steeply inclined longwall mining faces.

Long-distance protective layer mining is restricted by the long distance, the small pressure relief and the construction difficulty of through-layer drilling, so it will be beneficial for long-distance protective layer mining to study overburden movement law and pressure relief range. Take 9# coal seam (outburst) and 15# coal seam (non-outburst) as mining background, this paper adopted theoretical analysis, similar simulation and field test to analyze the characteristics of "two zones" distribution in roof and gas flow law after long-distance protective layer mining, to discuss roof movement of working face and stress distribution law, and designed the mining scheme of long-distance protective layer. The results showed that the pressure relief of protected layer was mainly related to the height development of the "two zones", and the protected layer was in the bending subsidence zone in engineering mine; after the mining of the lower protective layer, “three zones” appeared above the protective layer, the difference between the curves of both sides of cut hole and stop-mining line were obvious, the subsidence of coal roof was the most obvious, the one near the protected layer roof more moderate, and the one on the upper more obvious; the abutment pressure in front of the working face of the protective layer increased firstly, then decreased and finally increased slowly with working face advancing; the stress of the protected layer increased slowly firstly, then decreased and finally increased slowly with working face advancing; during the mining of the protective layer, the periodic weighting was obvious, and the average collapse step of periodic weighting was 17 m, the fracture development zone formed to trapezoid as working face advance 243 m, the upper caving Angle is 69°, and the lower caving Angle 62°; 9# coal gas could be extracted from the 15# through-bed drilling, the gas extraction concentration had a slight decline trend with the increase of time, the gas concentration dropped to 3.8% in day 65, and the extraction effect was significant.

The geological conditions of coal-rock roadways are complex, and the anchoring performance of bolts across layers is constrained by multiple factors, leading to suboptimal support effectiveness. This study focuses on the key influencing factors of bolt anchoring performance in coal-rock roadway support. Firstly, the physical and mechanical parameters of different coal seams and roof-floor strata in typical mines were obtained, combined with the hollow inclusion stress relief method to measure in-situ stress distribution within the roadway. Based on field data, a numerical model was established to invert the stress state of the bolt working environment during excavation and mining, determining a confining pressure range of 0–15 MPa. Through laboratory tests, the influence patterns of different coal-rock strength ratios (1:2, 1:3, 1:4, 1:5), confining pressures (0, 5, 10, 15 MPa), and cross-layer anchoring methods (coal-to-rock, rock-to-coal) on the load-bearing performance of coal-rock composite anchorages were systematically analysed. The results indicate that: Increasing the coal-rock strength ratio significantly enhances the ultimate pull-out load of bolts (from 45.4 kN at 1:2 to 68.79 kN at 1:5); Higher confining pressure effectively improves anchorage stability (ultimate load increases from 34.52 kN at 0 MPa to 77.55 kN at 15 MPa); The coal-to-rock anchoring method demonstrates superior performance compared to rock-to-coal, exhibiting delayed interface debonding and higher residual strength. These findings provide theoretical and experimental support for bolt support design in coal-rock roadways under complex geological conditions.

In recent years, China's coal mining is huge, and the healthy operation of the mining equipment gear transmission system is a prerequisite for ensuring efficient coal mining and safe underground operation. Gear transmission device as the core component of mechanical equipment, its operating conditions are complex, and the vibration signals of many structural components overlap, making it more difficult to monitor and requiring in-depth analysis by professionals. In view of the challenges faced by the monitoring of the gear transmission system of mining machinery and equipment, this paper firstly reduces the vibration signals based on the joint noise reduction algorithm of modal preference reconstruction and expression (CEEMDAN), and further constructs a fault diagnosis model based on the long and short-term memory (LSTM) neural network. At the same time, the gray wolf algorithm is improved in three aspects, namely, population initialization method, convergence parameter updating strategy, and location updating strategy, and after performance testing and comparison with other algorithms, it is found that the three improvement measures adopted in this paper significantly enhance the performance of the gray wolf algorithm. Finally, the improved Gray Wolf algorithm is used to optimize the hyperparameters of the fault diagnosis model. After simulation analysis and experimental verification, the fault diagnosis model proposed in this paper, compared with the traditional model, the diagnostic accuracy and stability have been greatly improved, and the average accuracy of identification can reach more than 96%.

As the ' throat ' connecting the upper and lower mines, the operation state of the mine hoist directly affects the production efficiency and safety of the mine, and the braking system is an important guarantee for the stable operation of the hoist. In order to reduce the dependence on expert experience and fully exploit the complex relationship between data, a fault diagnosis method of lifting braking system based on improved Transformer neural network is proposed. Firstly, the fault phenomena and causes of the braking system are analyzed, and the monitoring parameters are determined. Secondly, an improved Transformer fault diagnosis model is built, and a multi-layer self-attention mechanism is used to capture the correlation and fault relationship between the monitoring data of the mine hoist. The pooling layer is introduced into the Transformer model to reduce the parameters of the model and alleviate the risk of over-fitting. Finally, the experimental research is carried out based on the actual operation data of the hoist. The Adam optimizer is used to update the model parameters. The results show that the accuracy of the improved Transformer fault classification prediction can reach 97.5 %, which is 6.1 %, 10.0 % and 14.8 % higher than that of Transformer, CNN and LSTM neural network, respectively.

The complex and variable formation conditions pose a great challenge to safe and efficient production in coal mines. By establishing a drillability prediction model based on drilling data, intelligent perception of formation types can be achieved, providing geological information support for the drilling process.Addressing the issues of outliers and unbalanced sample sizes in coal mine drilling data, we employ the Local Outlier Factor (LOF) anomaly detection algorithm to remove abnormal drilling data. Additionally, we leverage a Generative Adversarial Network (GAN) to train on the original drilling samples, thereby obtaining generated drilling samples to construct a balanced drilling dataset.A method for predicting the drillability of a formation using a whale optimization algorithm-based kernel extreme learning machine (WOA-KELM) is proposed, which combines the drillability of the formation as an evaluation index. A prediction model based on the optimized WOA-KELM is constructed to predict the level of drillability of the formation.Through the actual drilling data in Huainan mining area, we obtained drilling parameters such as weight on bit (WOB), rotation speed, and penetration rate. After eliminating outliers using LOF, GAN was used to generate samples with high similarity to the original ones. The reliability of these generated drilling samples was verified through box plots, recognition rates, and scatter plot distributions.Using the generated sample balanced drilling dataset, a formation drillability prediction model was established through WOA-KELM for drilling process. The accuracy of formation drillability prediction reached about 98%, which is superior to recognition models such as SVM and KNN.The research results provide a reference for the adaptive drilling and intelligent perception technology in coal mines.

In the process of coal mining, the coal body in the mining space is always under the combined disturbance of mining dynamic load and high static load, and it is difficult to determine the pressure relief position of the overburden under the combination of dynamic and static loads due to the fact that the cumulative characteristics of superimposed damage caused by cyclic load and creep are not clear. To this end, the MTS815 testing machine was used to carry out different axial creep compression tests after cyclic addition and unloading under the condition of confining pressure of 10MPa. The results show that the elastic modulus of unloading is higher than that of the loading process in the cyclic loading cycle. The Poisson's ratio showed a similar trend, and the gap between the elastic modulus and the Poisson's ratio became smaller during loading and unloading. The stress-strain response exhibits hardening and softening effects under constant deviator stress, and the triaxial?compressive?strength (TCS) has a dominant hardening effect under low deviator stress. On the other hand, the softening effect is more obvious under the action of higher deviator stress. The evolutionary characteristics between axial strain rate and volume strain rate can be well described by the negative exponential function relationship. The coal and rock mass at the boundary of mining pressure relief has experienced periodic failure and continuously increasing creep stress. Therefore, based on the creep evolution law of coal and rock mass, the appropriate time is selected to determine the boundary, which provides a quantitative basis for the prevention and control of disasters dominated by stress evolution. This study can provide a certain reference for preventing coal and rock dynamic disasters and determining the spatial location of pressure relief gas extraction.Key words: Mining-induced stress; creep rate; fatigue damage; hardening effect; gas drainage

The rock itself is inhomogeneous, and the plastic failure of the aquifuge rock mass within the failure range of the coal seam floor occurs due to coal seam mining. The adjacent roadway excavation and working face mining and other projects lead to the rock mass undergoing cyclic loading and unloading process after failure. In order to investigate the effect of post-peak cyclic loads on the mechanics and permeability of rock masses with axial hole defects, and to clarify the influence of repeated engineering disturbance on water inrush of defective floor rock mass, the following was done. A post-peak cyclic loading test study was carried out on sandstone with holes of 5, 10, 15, and 20 mm under a confining pressure of 20 MPa. This study was based on the rock adaptive multi-field test instrument. The results show that : ( 1 ) In the conventional triaxial compression stage, the permeability of rock increases and decreases with the closure and development of internal cracks in rock. The brittle failure characteristics of rock with 5 mm pore size are obvious, and the rock with 10 mm, 15 mm and 20 mm pore size is intermittent. ( 2 ) In the post-peak cycle stage, the change of rock permeability shows a regular cycle with the action of axial pressure and confining pressure. In the cyclic unloading stage, the rock permeability increases rapidly and decreases rapidly. ( 3 ) Cyclic loading and unloading causes cumulative damage to the rock, and the cyclic bearing capacity of the rock decreases with the increase of the pore size. The total amount of seepage channel expansion of the rock containing pores under post-peak cyclic loading and unloading is greater than the total amount of rock particle accumulation and blockage in the seepage channel. ( 4 ) The failure mode of rock with holes is still transfixion shear failure. The cyclic loading makes the secondary shear cracks develop and the degree of crack development increases with the increase of pore size, and the failure mode of rock tends to be complex.

Existing coal safety supervision mostly adopts the mode of "people-oriented", which has problems such as strong subjectivity and high energy consumption. It can easily lead to negligent behaviors such as playing cell phones, smoking, sleeping on duty, and it is difficult to ensure that the coal mine safety production is carried out in a stable and orderly manner. In view of this, this paper utilizes the target detection technology, based on deep learning method, to study the intelligent recognition method of the working status of the personnel in the coal mine dispatching room. First, a YOLOv5-based method for recognizing the working status of personnel in coal mine dispatching room is constructed; Then, a convolutional attention module is introduced into the feature fusion sub-network in order to enhance the information extraction ability of the model in different channels and different spatial locations; Finally, the stepped residual convolution module with multi-scale feature fusion capability is used to enhance the model's ability to extract subtle features and fuse global features of personnel in the dispatching room. The experimental results show that the average accuracy rate of the full-state recognition of the method proposed in this article reaches 91.7%, and the average accuracy rate of small-scale action state recognition such as playing with mobile phones and smoking is 94.4% and 86.0% respectively, which verifies the effectiveness of the proposed model in identifying the working status of dispatchers.

the coal mine wastewater with high salinity is difficult for efficient treatment by traditional coagulation and precipitation methods. we designed an effective process of micro-bubble air flotation system for coal mine wastewater treatmen. The influences of dissolved gas pressure and gas-water ratio on particle size distribution and stability of micro-bubbles were studied, as well as the influences of dissolved gas pressure, gas-water ratio, water salt content, oil content and chemical dosage on oil removal effect were also studied. The results showed that when the microbubble generator is operated under the conditions of 0.55 MPa dissolved gas pressure and 6% gas-water ratio, the stability of the microbubble is the best, the average particle size is as low as 9.24 μm, and the oil removal rate can reach 45.80%. Under the condition of higher oil concentration and higher salt content, the system still maintains 40% treatment effect. Response surface method was used to optimize the dosing combination, and the optimal dosing ratio of PAC dosing concentration of 107.900 mg/L, cationic PAM dosing amount of 10.034 mg/L, and compound demulsifier dosage of 90.000 mg/L was determined. At this time, the removal efficiency of emulsified oil could be increased to 94.52%. Therefore, the micro-bubble air flotation technology has high efficiency and applicability in the treatment of mine water with high salt and high emulsified oil content.

The injection rate of gasification agent is an important factor affecting the yield of gasification products and gas calorific value in the process of underground coal development. In order to reveal the effects of residence time and heating rate on the gasification behavior and product distribution characteristics of lignite in Santanghu Basin, the gasification and pyrolysis experiments of Xishanyao Formation lignite in Santanghu Basin under different residence time and heating rate were carried out based on a fixed bed gasifier. The results show that（1）with the increase of residence time, the conversion rate of semi-coke and gas yield increase, and the water yield increases first and then decreases. Under high temperature conditions, the secondary reaction is aggravated, and the methane conversion reaction is promoted, resulting in a significant increase in the volume of H2, but the total mass of pollutants is reduced.（2）With the increase of heating rate, the semi-coke conversion and gas yield decreased, and the yield of water and tar decreased first and then increased. Under high temperature conditions, the secondary reaction is inhibited, the volume of H2 is reduced and the total mass of pollutants is increased.（3）It is suggested that in the actual production process, by controlling the moving speed of steam injection to increase the residence time and reduce the heating rate, the generation of H2 can be significantly increased, so as to improve the efficient and clean development of underground coal gasification process. The research results can provide theoretical guidance for the underground coal gasification process of lignite in Xishanyao Formation of Santanghu Basin.

A hybrid PFM-PWM control strategy based on dynamic surface control is proposed to address the stability, fastness and tracking of the CLLC converter high order system for power transfer under full load condition. This control method can use PWM control and with PFM control strategy in light load and full load state respectively, based on this hybrid control strategy CLLC resonant converter can switch modes according to the output voltage value. This paper analyzes the topology of the CLLC resonant converter in detail, analyzes the operating waveforms of the under-resonant state, the resonant point state and the over-resonant state, and comes up with a specific implementation scheme of the hybrid control strategy for the dynamic surface. Combined with the characteristics of the mining locomotive charger to the use of MATLAB/Simulink simulation and physical experiments to prove the feasibility of the proposed control method.

The exposed steel wire rope of the landing multi rope friction hoist runs under the conditions of low temperature, wet and cold, rain and snow in winter, which has the problem of surface icing. The ice on the steel wire rope is easy to reduce the friction coefficient of the hoisting system, which will cause the creep and slip of the steel wire rope, and may cause the hoisting accidents such as sliding rope and stall in serious cases. Therefore, the author puts forward a design idea of the wire rope deicing and drying device suitable for the landing multi rope friction hoist, which uses compressed air as the working medium and is used by the annular air knife after filtering and heating. The annular air knife releases high-pressure, high-speed and high-temperature airflow to continuously impact and melt the ice on the surface of the steel wire rope, so as to achieve the purpose of deicing and drying.