Abstract:The monitoring of coal stress is an important part of prevention and control of rockburst,and the amount of coal fine obtained by drilling cuttings method is a widely used indicator.In order to reveal the influence of coal stress on surface energy and particle size distribution,a mechanical model of drilling process was established with the coal fine content of drilling cuttings method as the reference index.Coal drilling experiments were conducted and field engineering verification was carried out.The research results indicate that the surface energy of coal fine increases with increasing stress and is linearly related to the quantity of coal fine.The proportion of medium and fine-grained coal fine increases with the increase of stress,and the proportion of medium and fine-grained coal fine is linearly re-lated to the quantity of total coal fine.A new coal stress monitoring index has been proposed,which can provide technical reference for early warning of rockburst.

Abstract:Enhancing permeability and strengthening gas extraction in low-permeability coal seams is one of the important measures to improve the effectiveness of coal seam gas extraction,which can effectively solve the problem of coal seam gas control.Taking the No.3505 mining face of Huo'erxinhe Coal Mine in Shanxi Province as the research object,in response to its mechanical cavitation technolo-gy for enhancing permeability and strengthening gas extraction,the mechanism of coal seam permeability enhancement under different occurrence parameter conditions was revealed.The optimization of mechanical cavitation parameters,drilling structure design and lay-out,and optimization of drilling process parameters were carried out.The drilling structure parameters and layout suitable for under-ground coal seam gas drainage in Huo'erxinhe Coal Mine were designed,and the construction process of mechanical hole making and enhancement was optimized.The airbag type"three blockages and two injections"continuous high-quality sealing technology was pro-posed,and the overall layout optimization of mechanical cavitation and enhancement gas drainage drilling holes was completed.Research has shown that when the length of mechanical cavitation holes is 1.5 meters and the spacing between holes is 3 meters,the pure gas ex-traction and gas concentration of a single hole are both increased by 80％.The research provides scientific basis and practical guidance for improving the efficiency and effectiveness of gas extraction from low-permeability coal seams in the mine,shortening the half-life of gas extraction boreholes,and other aspects.

Abstract:The uneven distribution of rock layers in areas with abnormal sedimentary facies can easily lead to local stress concentration and rock fractures at sudden changes,resulting in a higher probability of dynamic events such as coal cannons and mining tremors than in areas with uniform sedimentary facies,which poses a threat to the safety production of working face.Taking Zhangshuanglou Coal Mine in Xuzhou mining area as the research object,its geological factors and sedimentary facies genesis were analyzed.It is found that under spe-cific sedimentary facies background,the coal thickness variation zone and the area with significant differences in roof thickness have dense distribution of mine tremors,especially in the coal thickness transition zone and steep change zone,which are prone to stress concentration due to static loads.The research results provide useful references and guidance for the prevention and control of rockburst in similar geo-logical environments.

Abstract:In order to effectively reduce the gas content and pressure in coal seams and mitigate the threat of coal and gas outbursts,a study was conducted on the application of hydraulic fracturing extraction technology to improve gas extraction efficiency in No.5 coal seam of a certain coal mine.An efficient gas extraction plan suitable for mine was proposed.The results indicate that the application of hydraulic fracturing extraction technology has significantly improved the gas extraction effect of the Lower5 coal seam,ensuring the safety production of mine.

Abstract:Coal gangue and fly ash are two common types of solid waste in mining areas.The discharge of these wastes not only occupies a large amount of land resources,but also causes serious harm to the ecological environment,becoming an urgent environmental problem that needs to be solved.Taking into comprehensive consideration of characteristics of coal gangue and fly ash,the two were crushed and mixed.By adding microbial activators(sludge)and inoculating functional microorganisms(such as arbuscular mycorrhizal fungi AMF),a"mineral-organic-microorganism"ternary synergistic improvement system was formed.This system not only brings organic matter and nutrients to matrix,but also increases the number of microorganisms in matrix and stimulates their growth,achieving rapid maturation and sustainable remediation of soil in the mining area.This system can meet the needs of plant growth and fully utilize solid waste in mining areas,providing reference for ecological utilization of coal-based solid waste.

Abstract:The construction of intelligent coal mines requires coal mines to establish an integrated underground communication system and equip corresponding equipment according to their own geological and production conditions,using 4G wireless communication,Wi-Fi6,Industrial Ethernet,bus and other coal mine communication protocols are integrated into a multi-technology fusion communication device.In response to the current situation of multiple underground equipment,disorderly cables,and difficult maintenance in coal mines,a 10 gigabit wired redundant network was utilized to construct a"one network,one station"high-speed transmission channel to improve equipment utilization.The 4G+Wi-Fi6 intrinsically safe base station studied can connect fixed telephones,wireless telephones,emergency broadcasting,video surveillance,personnel positioning and other systems,realizing interactive sharing and decision support of multiple departments,specialties and multi-technology integration,eliminating communication barriers,achieving unified command,and is of great significance for ensuring coal mine safety production and improving the level of intelligent construction.

Abstract:Relative sensitivity is an indicator that reflects the changes in predictive indicators with the risk of coal seam outburst.It is based on the lowest measured values of each predictive indicator during the statistical period,and calculates and calculates the average and maximum relative sensitivity of each predictive value during the prediction period,quantitatively reflecting the sensitivity of each predictive indicator to the predicted risk of coal seam outburst.The prediction of mining face outbursts in three coal mines were tracked,the relative sensitivity of each prediction indicator was calculated,and the gas dynamic phenomena during the prediction period was ana-lyzed.The results indicate that the average relative sensitivity of unit length of borehole gas emission index was more than 2 times higher than other predictive indicators,and the highest value was more than 5 times higher than other indicators.The study provides a new ana-lytical method for determining sensitive indicators for predicting coal seams.

Abstract:In order to actively respond to the national and Jiangsu Province's requirements for intelligent construction of coal mines,Zhangshuanglou Coal Mine has built the No.74104 working face into an intelligent working face based on underground geological condi-tions,achieving centralized control of production equipment such as one click start stop,operation monitoring,video monitoring,and au-tomatic coal cutting and relocation from the ground and underground.The application of intelligent mining technology has significantly improved the automation level of comprehensive mining,improved the working environment and safety conditions,reduced labor intensi-ty,and achieved the goal of"reducing staff and improving efficiency,and ensuring safety without anyone".

Abstract:High sulfate mine water poses serious hazards to the ecological environment and water resource utilization,while permeable reactive barriers can effectively treat high sulfate mine water at a relatively low cost.To investigate the adsorption effect of various adsor-bent materials in permeable reactive barriers(PRB)on sulfate ions under different ratios and determine the optimal ratio,indoor static adsorption experiments and PRB dynamic reaction column experiments were conducted.Theoretical analyses such as adsorption kinetics and isothermal adsorption models were employed to study the optimal ratio and usage conditions of the selected adsorbent materials.The results showed that sand,zeolite,and volcanic stone exhibited good adsorption effects on sulfate radicals,with an optimal dosage of 100 g/L.When the mass ratio of sand:volcanic stone:zeolite was 1:4:1,the best removal effect on sulfate radicals was achieved in Group ⑤(sand:volcanic stone:zeolite mass ratio of 1:4:1),with a sulfate radical removal rate of 47.84％in the static adsorption experiment and a sulfate radical removal rate of around43％during the adsorption stabilization phase in the column experiment.The ad-sorption process of the adsorbent material on SO42-was chemical adsorption and multilayer adsorption.

Abstract:As a typical geological condition that induces rock burst,hard roofs are characterized by high strength,high bearing capacity,high integrity,and low jointing,posing a serious threat to safe and efficient production in mines.To accurately predict rock burst disas-ters under this geological condition,a NOA-CNN rock burst early warning model was constructed.The NOA algorithm was utilized to optimize three hyperparameters of CNN:learning rate,batch size,and regularization coefficient,with their optimal values being 0.016 3,175,and 0.023 6,respectively.When training the NOA-CNN model,the accuracy rates of its training set and test set were 98.12％and 98.62％respectively.When training the CNN model without hyperparameter optimization,the prediction accuracy rates of both its train-ing set and test set were lower than those of NOA-CNN model,and the false negative rate and false positive rate of CNN model in-creased by 94.4％and 0.2％respectively.Research indicates that the NOA-CNN model excels in mining deeper potential features from microseismic data,delivering superior early warning performance,and is more suitable for predicting rock burst,thereby ensuring coal mine safety.

Abstract:To study the air leakage laws and spray sealing technology for small coal pillars in fully-mechanized caving face,Shaanxi Jianxin Coal Chemical Co.,Ltd.was selected as the research subject.By utilizing energy level test and SF6 tracer technology,an analysis was conducted on the arrangement of small coal pillars on its No.4301 mining face and the prevention and control of coal spontaneous combustion in the adjacent No.4300 goaf.The air leakage laws between the two were explored to identify the leakage locations.Based on this,research was conducted on the spraying technology for small coal pillars and fire prevention and extinguishing materials.FLAC3D software was used to analyze the reasonable spraying thickness of small coal pillars.The research results indicate that after applying plastic spraying materials in the air leakage area of small coal pillars,both the sealing and supporting effects have been significantly im-proved,ensuring safe extraction of working face.

Abstract:To prevent damage to grouting boreholes caused by overburden movement,a smaller-diameter tubing is typically run inside the technical casing as the grouting pipe.Adopting this measure is merely a passive prevention approach,and it severely restricts the de-livery of grout,contradicting the requirement for a large amount of grout injection during initial grouting.If the initial grouting volume fails to meet the requirement of"supporting the key stratum by compressing and supporting the upper part"of isolation wall and grou-ting filling body,it will cause the sliding or deformation instability of"voussoir beam"block of the key stratum.If the overlying strata continue to move,the boreholes will be damaged,ultimately leading to the failure of stowing project.Based on the theories of"voussoir beam"as the key layer for overlying strata separation grouting,"four zones"in the strike direction,and strata movement angles,a de-sign method for preventing damage to the first row of boreholes during strata separation grouting was proposed using directional drilling technology,and has been applied on-site.Practical application has proven that this design not only meets the requirement of a large ini-tial grouting volume for the first row of boreholes,but also shifts from passive prevention to active control,eliminating potential safety hazards.This design can also be applied to the last row of grouting boreholes outside the working face cut and to the"isolated island"type of first and last row grouting holes in the middle.

Abstract:Addressing the challenges of roadway supporting in isolated working faces of thick coal seams,taking the No.8303 working face of Tashidian Coal Mine as the engineering background,a numerical calculation model was established to study the stress distribu-tion characteristics of surrounding rock during mining on the working face,and to analyze the supporting effectiveness of existing road-way supporting scheme.The research results indicate that due to the high stress environment in which the roadway is located,there is a significant displacement of the roof,floor,and two sides of the roadway,with a wide range of influence,causing substantial damage to the surrounding rock.The roadway is in a highly unstable state.The introduction of new grouting anchor cables has been utilized for the op-timization design of roadway supporting schemes,and the effectiveness of optimized scheme has been verified using numerical analysis methods.The research results can provide technical supporting for the development of supporting system for isolated working faces in thick coal seams.

Abstract:Addressing the issues existing in the coal mine safety training mode,the VR intelligent training system was utilized to create an immersive learning experience scenario,the safety training mode was optimized,and it was applied in the safety(talent)training center of Shaanxi Guojiahe Coal Industry Co.,Ltd.Application practice has shown that incorporating the VR intelligent training system into coal mine safety training significantly enhances learners'interest in learning and effectively boosts their learning efficiency.Conse-quently,this greatly improves the quality of coal mine safety training and provides a safeguard for the implementation of coal mine safety work.

Abstract:Air compressors are auxiliary production equipment or power equipment in the manufacturing industry,with their energy con-sumption accounting for 8％to 10％of the total energy consumption of enterprises.The high performance and reliability of the screw air compressors have made them the preferred choice for coal-fired power units.Taking the screw air compressor unit of Jiangsu Xuzhou Mining Comprehensive Utilization Power Generation Co.,Ltd.as the research object,the current operating status of the compressed air equipment system was investigated,its existing problems and potential for energy saving were analyzed,and optimization and renovation plans were proposed.The implementation of the plan not only ensures the safe and stable operation of unit and reduces operating costs,but also promotes synergistic effects in energy conservation and emission reduction for the enterprise,enhancing its market competitive-ness.

Abstract:As the depth of coal mining increases,the surrounding rock medium exhibits multi-scale geological anisotropy,leading to a significant increase in mine pressure.To explore the characteristics of ground pressure and its influencing factors under the condition of roof cutting and pressure relief self-forming roadways,taking the self-forming roadway without coal pillars at No.21802 working face of a certain mine as an example,the FLAC3D software,which is suitable for simulating large deformation problems in underground excava-tion,was utilized to analyze the influence of factors such as the presence or absence of cutting seams,roof cutting height,and angle on ground pressure.The results indicate that the roof cutting and pressure relief technique can interrupt the stress transmission between the roadway and the roof of the mined-out area,reduce the degree of stress concentration in the solid coal pillar,and shift it towards the deeper part,thereby optimizing the stability of the roadway.The increase in roof cutting height can expand the pressure relief range of roadway roof,reduce the peak stress,decrease the vertical displacement of roadway roof,and enhance the convenience of roadway main-tenance.A moderate cutting angle facilitates the collapse of the roof in the mined-out area,enabling rock mass to fill the mined-out are-a and support the upper rock strata.Although the vertical displacement of roadway roof increases with the increase of roof cutting angle,when the roof cutting angle is 0°and 15°,the stress increase zone transfers to the deep part of the solid coal,which is conducive to the stability of surrounding rock of roadway.Especially at a roof cutting angle of 15°,the vertical concentrated stress is minimal.The re-search results provide theoretical and technical support for the design of roof cutting and pressure relief in practical engineering.

Abstract:Aiming at the problem of serious roadway deformation caused by mining-induced ground pressure in thick coal seam mining,on the basis of combing the difficulties in the prevention and control of mining-induced ground pressure in thick coal seam,the theoretical a-nalysis,indoor test,numerical simulation and field measurement methods were comprehensively used to study the application effect of roof breaking decompression technology in adjacent roadway for mining-induced ground pressure in thick coal seam.The results show that the influence range of mining-induced ground pressure in thick coal seam is wide,the stress is complex,the ground pressure manifestation is strong,and the support design and management are difficult;by cutting off the connection between the roof of the goaf and the roof of the roadway,the roof breaking decompression technology in adjacent roadway can reduce the amount of borehole drilling and the damage of the surrounding rock,and has the technical advantages of low comprehensive cost and simple process;through numerical simulation and field experiments,the deformation of roadway under the condition of broken roof and unbroken roof is compared and studied.The technology of breaking decompression in adjacent roadway can effectively cut off the stress transfer of roof and reduce the deformation of roadway signifi-cantly.The research results can provide reference for the prevention and control of mining-induced ground pressure in thick coal seams.

Abstract:Taking the ground well extraction of coalbed methane from the abandoned coal mine goaf of Xinghua Coal Mine in Jixi mining area as an example,the occurrence characteristics of coalbed methane in the abandoned mining area were analyzed,the scope of gas storage space in the abandoned mining area was studied,the influence of the"O"shaped fracture circle on the occurrence of coalbed methane was clarified,and the constraints of resource occurrence conditions in goaf on the construction of ground wells and gas produc-tion characteristics of ground wells were defined.Research results indicate that when ground wells are deployed in goaf with abundant coalbed methane resources,high resource abundance,and good resource preservation conditions,and when the well locations are con-structed in the fully decompressed area of the"O"shape fracture zone in goaf,a stable production of 10 000 m3/d of coalbed methane with a methane concentration ranging from 28％to 58％can be achieved.

Abstract:Taking Pingshu Coal Industry Co.,Ltd.(hereinafter referred to as Pingshu Company)mine as the engineering background,a study was conducted on its coal and gas outburst prevention and control system.Through the application of comprehensive prevention and control measures such as mining protection layer,floor rock pre extraction roadway through layer drilling pre extraction,bedding drilling pre extraction,and"small coal pillar"pressure relief and outburst elimination,the problem of coal and gas outburst was effec-tively eliminated.The results indicate that the deformation of the protected layer after mining is 5.6 ‰,which meets the relevant judg-ment criteria;the use of small coal pillars for pressure relief mining has an effective pressure relief protection range of 31.5 meters from the edge of the goaf,and the pressure relief is effective;experiments were conducted using through layer drilling combined with hole making and permeability enhancement technology,compared with ordinary gas extraction technology,hydraulic hole making and permea-bility enhancement technology has a more significant gas extraction effect,providing better safety guarantees for achieving mine safety production.

Abstract:In order to further recover coal resources and extend the service life of mine,Yunhe Coal Mine has carried out re-mining and recovery work on the coal resources remain from the original first mining area of the No.3 coal seam.The re-mining area is located within the goaf of No.1301 and No.1302 fully-mechanized mining faces in the original first mining area.The coal seam is a Class Ⅱspontaneous combustion coal seam,and fire prevention and control have become important tasks in this working face.Therefore,this study analyzes the potential risk of spontaneous combustion of coal seams in the secondary mining area,monitors the content and tem-perature change of natural combustion marker gas through the gob bundle and temperature probe,proposes the"three zones"distribu-tion of natural combustion,pressure equalization to reduce the risk of coal spontaneous combustion,network parallel electrical method to monitor the spread of gel,and other fire prevention and extinguishing technologies in the secondary mining face,and carries out engi-neering applications to ensure the safe and smooth recovery of the secondary mining face,and provides reference for the formulation and optimization of mine fire prevention and extinguishing schemes under similar conditions.