Abstract:To enhance the flotation efficiency of scarce coking coal slime,a 1/3 coking coal from Xinwen Coal Preparation Plant was selected as the research object,with n-hexane and cyclohexane chosen as flotation reagents.The influence of long-chain and cyclic molecular structures on the flotation performance of coal slime was systematically investigated.Through flotation experiments,spreading angle tests,Density Functional Theory(DFT)calculations,and molecular dynamics simulations,the mechanism of reagent molecular structure on flotation performance was revealed from both macroscopic and microscopic perspectives.The results show that n-hexane exhibits superior flotation performance compared to cyclohexane:at a collector dosage of 2000 g/t,the combustible recovery of n-hexane reached 68.93%,while that of cyclohexane was only 64.79%.Spreading angle tests indicated that the spreading angle of coal slime particles treated with n-hexane was 178°,significantly higher than the 152° for cyclohexane.DFT analysis revealed that the Molecular Polarity Index(MPI)of n-hexane is 2.85 kcal/mol,higher than the 2.45 kcal/mol for cyclohexane,indicating stronger adsorption capacity on the coal slime surface.Molecular dynamics simulations further confirmed that n-hexane spreads more effectively and exhibits lower mobility on the coal slime surface compared to cyclohexane.The findings demonstrate the significant advantage of long-chain structured collectors in the flotation process of coal slime,providing a theoretical basis for the molecular design of high-performance flotation collectors.

Abstract:The fracture propagation effect in thick-hard roof strata during hydraulic fracturing is critical for evaluating the technology's effectiveness in preventing rock bursts.Taking the hydraulic fracturing operation in the thick-hard roof strata of the 20101 working face as an engineering case study,we investigated the fracture propagation through surface microseismic monitoring and the small-volume covering ellipsoid method.The results demonstrate that:Firstly,within the total fracturing length of 1000 m,a total of 1255 microseismic events were monitored.The fracture propagation range is positively correlated with the volume of fracturing fluid used but unrelated to the fracturing operation time.As the number of microseismic events increases,the fracture propagation range in the thick-hard rock layer expands.Secondly,centered on the horizontal well,the average radii of hydraulic fractures in the north-south horizontal direction,east-west horizontal direction,and vertical direction are 127 m,71 m,and 31 m,respectively.The stimulated reservoir volume(SRV)after hydraulic fracturing of the thick-hard rock layer is 371.2×104 m3.Thirdly,the water discharge observed at the underground drainage borehole sites is generally consistent with the fracture propagation results from surface microseismic monitoring.These findings confirm that surface microseismic monitoring technology is effective to evaluate the fracture propagation effectiveness of hydraulic fracturing,providing a scientific basis for fracture assessment and rockburst prevention effect analysis under similar conditions.

Abstract:To comprehensively promote the application of BIM technology in coal mine design enterprises,based on the practical experience of the author's design firm,this paper first analyzes the various issues encountered during the technology's promotion within the enterprise.A systematic roadmap for constructing an enterprise-level BIM technical application system is proposed,encompassing seven key dimensions:organizational structure setup,technical team development,software and hardware configuration,project implementation and application,enterprise family and model libraries,standards and guidelines,and supporting measures.The roadmap identifies technical team development as the foundation and core focus,with project implementation serving as the key driver.After four years of systematic development,BIM technology has been largely popularized among middle-aged and young design professionals.It has been successfully applied in depth across various engineering projects,including mine feasibility studies,underground cooling systems in coal mines,and coal storage and distribution bases,as well as in engineering procurement and construction(EPC)contracting.A rich repository of professional family libraries has been accumulated,and design workflows and empirical knowledge from practice have been formalized into enterprise standards and guidelines.This effort has established a solid and practical application platform for the comprehensive internal promotion of BIM technology.

Abstract:Investigating the gas desorption law under compressed air sampling and exploring methods for determining lost gas volume are significant for improving the accuracy of coal seam gas content measurement.First,an experimental gas desorption apparatus was developed to simulate coal seam gas content measurement via compressed air sampling.Then,optimal experimental parameters for coal sample particle size and driving air pressure were determined through experiments,and the gas desorption law under different operating conditions for gas content measurement via compressed air sampling was systematically investigated.Finally,the intrinsic mechanism by which compressed air sampling promotes gas desorption from coal samples was analyzed,a correction method for estimating the lost gas volume under compressed air sampling was proposed,and this method was applied in field tests.The results show that compressed air sampling induces vibration,fragmentation,and dilution effects on gas-bearing coal samples,and the synergistic action of these three effects effectively promotes gas desorption.At the transition point between the initial air-driving desorption phase and the subsequent static atmospheric desorption phase,a distinct inflection point appears in the slope of the gas desorption curve.The relative error between the estimated lost gas volume,determined based on the subsequent static atmospheric desorption law,and the actual gas desorption amount during the initial air-driven phase was 24.2%-61.8%.After applying the correction method,this relative error was reduced to 1.5%-14.0%.Field tests indicate that the measured coal seam gas content increased by 1.13%-6.86%after correction compared to the uncorrected values.

Abstract:To rationally determine coal pillar width for gob-side entry driving under secondary mining conditions,a study was conducted on gob-side entry based on the roadway layout and engineering geological conditions of Qianyingzi Mine.Theoretical analysis,numerical simulation,and field practices were employed.The theoretical width range of the coal pillar was calculated using the limit equilibrium theory.Combined with numerical simulation,the distribution characteristics of stress and displacement in the surrounding rock of the gob-side entry under coal pillar widths of 4～8 m were analyzed.The results show that under these geological conditions,the reasonable coal pillar width ranges from 4 m to 8 m.When a 5～6 m coal pillar is retained,the stress state of the pillar improves,achieving a balance between economic benefits and roadway stability.Considering multiple factors,a 6 m coal pillar was determined to be optimal for the gob-side entry driving of the E3215 return airway.After implementing bolt-cable combined support for the small coal pillar and subsequent grouting,the maximum deformations of the roof-floor and two sides of the E3215 return airway were 154 mm and 196 mm,respectively.The overall deformation of the roadway remained within a controllable range.The 6 m coal pillar combined with the surrounding rock control technology for gob-side entry driving effectively ensures the stability of the double-roadway coal pillar and achieves long-term effective control of the surrounding rock.

Abstract:To meet underground production demands,blanking shafts and blanking chambers have become essential facilities for mine materials supply.However,the construction of blanking shafts and the material blanking process significantly affects the airflow-gas transport within the chamber,an issue particularly prominent in high-gas mines.To clarify the impact of blanking shaft construction and the blanking process on the airflow-gas distribution characteristics inside the chamber,a physical model of coupled airflow-gas diffusion was established by introducing the gas component through a component transport model.We systematically investigated the influence of material blanking on the airflow-gas distribution patterns within the blanking chamber and shaft.The results show that without a blanking shaft,there is no significant airflow movement inside the chamber,leading to local gas accumulation.After the blanking shaft is operational,airflow enters the chamber along the shaft under pressure difference,forming vortices that effectively reduce the overall gas concentration in the chamber.However,gas accumulation occurs at the upper corner of the chamber,with a volume fraction over 0.09%.As the gas concentration in the system airflow increases,the gas dispersal efficiency driven by pressure difference gradually diminishes.Compared to pressure difference,increasing the system airflow velocity can more effectively reduce the gas concentration at the chamber's upper corner,with higher velocities yielding more significant dispersal effects.Additionally,forced ventilation using auxiliary fans leverages the Coanda effect to deliberately increase airflow in the upper corner,optimizing internal air distribution and dispersing accumulated methane.

Abstract:To address the instability and failure of coal-rock roadway ribs in deep inclined coal seams under high stress and mining disturbance,we take the gob-side entry retaining of the 2301 working face in Zhangji Coal Mine as the engineering background.Using theoretical analysis,numerical simulation,and field tests,the deformation and failure mechanism of the surrounding rock in coal-rock roadways is systematically investigated,and a cooperative control scheme of"roof cutting pressure relief+cross-layer surface strengthening support"is proposed.The results show that compression-shear failure within the coal mass and shear slip at the coal-rock interface are the main causes of roadway side deformation and instability.Effective measures for stabilizing the coal-rock roadway side include reducing rib loading and restraining interfacial slippage.The maximum additional compressive strength provided by bolts(cables)occurs when the angle between interface/cross-layer bolts(β)equals the interface friction angle(φs).Numerical simulations demonstrate that under the pressure relief-reinforcement system,coal mass deformation decreases by 26.1%and relative deformation between coal and rock reduces by 47.8%.Field monitoring verifies that this control scheme achieves 34.9%reduction in coal-rock roadway convergence,effectively restraining rib deformation in mining roadways.

Abstract:The borehole-instead-of-roadway technology has been gradually promoted and applied in gas extraction from coal mine goafs due to its ability to effectively increase fracture connectivity in the strata,enlarge the gas emission channel area,and thereby improve gas extraction efficiency.Based on the demand for existing large-diameter near-horizontal high-level directional drilling,we employed the helical cutter layout principle to optimize the circumferential arrangement of the blades,enhancing the bit's adaptability to near-horizontal boreholes.The bit profile was optimized to improve steering performance,and the waterway structure was adjusted to ensure effective flushing.Surface additive technology was selectively applied to harden the bit surface.Field trials were conducted with the newly developed bit in high-level"borehole instead of roadway"drilling at a coal mine in Huainan.The results show that when drilling into sandstone and siltstone layers in the coal seam roof,the average service life of two bits reached 1898.5 m.Compared with conventional PDC bits,the new bit shows significant improvements in service life,drilling efficiency,and steering accuracy.During drilling,the bit followed the preset trajectory smoothly,with stable drilling pressure,no whirling,eccentric wear,or cutter breakage.Cuttings were discharged smoothly without pump blockage,and no bit balling or nozzle clogging occurred after tripping out,verifying the rationality of the cutter layout and waterway design.The bit body showed no wear,cracks,or spalling,indicating that the surface additive process is appropriate.The bit meets the requirements for large-diameter directional drilling in"borehole instead of roadway"applications,providing a new solution for the design and manufacture of large-diameter directional bits.

Abstract:To address the issue that teeth surface wear in helical gears of mining vibrating screen exciters severely compromises the coal washing process,a dynamic numerical simulation model of the exciter helical gear-rotor coupling system was established.The time-varying meshing force of the gear pair was obtained using the fourth-order Runge-Kutta method.Based on the characteristics of mixed elastohydrodynamic lubrication(EHL),the dynamic evolution of the time-varying wear coefficient,roughness load ratio,and oil film deficit coefficient for both driving and driven gears during the meshing process was investigated comparatively.The wear depth of the driving and driven gears under mixed EHL,as well as the post-wear time-varying meshing stiffness and time-varying backlash,were subsequently derived.By integrating these factors,the vibration response of the exciter helical gear system under teeth surface wear fault was obtained,and the vibration response patterns in various directions caused by wear faults were revealed.It was found that,in addition to the enhanced nonlinear vibration of the system,the x-direction,z-direction,and torsional direction are all sensitive to gear wear,which can provide a theoretical basis for fault diagnosis of gear wear in vibrating screen exciters.

Abstract:To address the surrounding rock control in gob-side entry retaining with concrete roadside filling,laboratory tests were conducted to determine the uniaxial compressive strength of concrete filling under different curing ages,relationship between concrete strength and curing age,as well as the concrete peak compressive strength were obtained.Borehole imaging was used to determine the extent of surrounding rock loosening and failure at different locations along the roadway,based on which the minimum lengths of roof anchor cables and sidewall bolts for the retained entry were determined as not less than 4.90 m and 3.70 m,respectively.Numerical simulation was employed to identify the advance influence range of the working face and the degree of disturbance on the surrounding rock at different positions,establishing that the reasonable distance for advance reinforced support should be not less than 19.08 m.Based on these findings,a zoned asymmetric control technology for surrounding rock in concrete roadside filling gob-side entry retaining was proposed.The feasibility of this zoned asymmetric control technology was analyzed through indicators such as internal surrounding rock pressure within the filling,roof separation,and surrounding rock convergence,verifying the rationality of the research results.

Abstract:To address the severe mine pressure behavior encountered during equipment withdrawal in the retreat roadway of a fully mechanized top coal caving face in an ultra-thick coal seam,caused by unreasonable parameters for leaving top coal and support design during the final mining stage,we employed field investigation,theoretical analysis,and numerical simulation to investigate the optimal location of the retreat roadway,parameters for leaving top coal,and surrounding rock control measures.The results indicate that leaving top coal during the final mining stage markedly reduces the intensity of strata behavior at the working face.An overlying strata structure where the main roof fracture line is located above the goaf is most favorable for the stability of the retreat roadway surrounding rock.A reasonable distance for leaving top coal is 20 m,which ensures effective goaf filling and timely fracture and pressure relief of the main roof.An asymmetric support system employing zoned rock bolts and cables(Support Scheme VI)for the retreat roadway achieves interconnection of the pre-stress fields in the coal rib and roof,enabling targeted control of the surrounding rock based on the differential principle of strong versus weak support demands.Field practice demonstrates that combining an appropriate distance for leaving top coal with a scientifically designed support system yields significant control effects for the retreat roadway surrounding rock,reducing waste of coal resources and mitigating safety hazards associated with spontaneous combustion of residual coal.

Abstract:Traditional underground drainage pump houses in mines often feature structural complexity,construction difficulties,long construction periods,and harsh working conditions.To address these drawbacks,this paper presents the design concept and a specific solution for a roadway-free water distribution drainage pump house.By replacing conventional water distribution roadways,distribution shafts,suction shafts,and suction niches with a full-length,continuously arranged suction shaft,the proposed design has several advantages:simplified structure,higher mechanization level,reduced labor intensity,shorter construction duration,and easier long-term operation and maintenance.Compared with the traditional scheme,the roadway-free design shortens the construction period by 1.5 months and reduces the estimated investment by 0.711 million yuan,which is a 9.7%reduction.This approach shows broad applicability and potential for use in both coal and non-coal mining operations.

Abstract:To address the need for emergency refuge during sudden mine accidents,we aim to design mobile refuge chamber with rapid response and flexible deployment capabilities.By integrating the Analytic Hierarchy Process(AHP),the Function-Behavior-Structure(FBS)model,and the Theory of Inventive Problem Solving(TRIZ),a systematic and innovation-driven design methodology was developed.Firstly,AHP was applied to identify and quantify miners'emergency requirements,determining the key functional indicators.The FBS model was then employed to map functions to structural solutions,clarifying the design pathway.Finally,TRIZ tools were used to resolve design contradictions,enhancing the innovativeness and reliability of the scheme.Based on this integrated approach,a refuge chamber device was designed and validated through digital simulation using the ergonomics analysis software Jack.The results demonstrate that the proposed AHP-FBS-TRIZ integrated design framework can effectively guide the design focus,significantly improve design efficiency and overall performance,and provide a feasible solution for reliable,efficient,and rapid mine emergency refuge.The research result holds practical significance for improving mine disaster rescue effectiveness.

Abstract:To investigate the coupling mechanism between stress and seepage fields in rocks under triaxial continuous loading,seepage characteristics of red sandstone specimens were tested under different pore water pressures.The mechanical response and seepage characteristics of red sandstone under fluid-solid coupling were analyzed.Particle flow numerical simulation coupled with the Fipy method was employed for experimental validation and meso-interpretation,to reveal the development and propagation of cracks as well as seepage evolution under fluid-solid coupling.The influence mechanism of effective confining pressure on volumetric strain,mesoscopic fracture,and seepage was elucidated.The results show that,based on crack volumetric strain,the complete stress-permeability coefficient-strain curve of red sandstone under pore water pressure can be divided into four stages.Under effective confining pressure,a reduction in effective confining pressure at the upper end of the rock specimen promotes force chain breakage and microcrack initiation,thereby increasing seepage velocity and flow.Simultaneously,this leads to stress concentration and localized crack development at the lower end,ultimately inducing macroscopic fracture.Pores and cracks serve as the main channels for seepage,which evolves due to the generation of new pores and cracks under stress.The heterogeneity in pore structure and crack distribution across different regions results in spatial variability of the permeability coefficient.During rock fracture,seepage channels transition from dispersed microscopic pore networks to concentrated macroscopic fracture surfaces,significantly enhancing permeability and forming a continuous and relatively stable seepage path along the fracture surface.

Abstract:To provide a more reasonable and feasible"three-machine"matching scheme for ultra-long working faces in medium-thick coal seams,we proposed a matching scheme for a 450 m ultra-long fully mechanized working face at the 132202 working face in Xiaobaodang No.2 Mine,considering the geological conditions and mining processes for the 2～3 m medium-thick coal seam.The matching scheme was determined through systematically calculating the parameters such as the power matching of coal shearers,scraper conveyors and hydraulic supports,as well as the transportation capacity and dimensions of the installation space.Underground operation results showed that,the matching scheme was reasonable,the equipment operated well,and the expected productivity(ten million tons per year)was achieved.This matching scheme provided both theoretical and practical experience for achieving mechanized mining of ultra-long working faces in medium-thick coal seams under similar conditions and contributes to the further development of ultra-long working face applications.

Abstract:Traditional coal wastewater treatment processes often suffer from low solid-liquid separation efficiency,high dependence on chemical agents,and insufficient reclaimed water reuse rates.To address these challenges,this study focuses on a typical coal preparation plant in an alpine mining area of Inner Mongolia.An innovative silicon carbide ceramic membrane separation system was developed,employing surface modification and dynamic filtration to enhance the synergistic adsorption-sieving mechanism at the ceramic membrane interface.Key parameters and the process flow were optimized and integrated with online air-water pulse backwashing technology to achieve efficient short-process resource recovery from wastewater.Engineering practice demonstrated that,even under significant fluctuations in influent COD,turbidity,and oil content,the system consistently achieved removal rates exceeding 97.5%for major pollutants(SS,petroleum substances,and COD),increased the reclaimed water reuse rate to 97.6%,and reduced operational cost per ton of water by 61.8%.Tailored to the characteristics of alpine mining area wastewater,this research proposes a highly efficient short-process treatment technology based on ceramic membranes,offering a new technical pathway for wastewater resource recovery and industrial near-zero discharge.

Abstract:The Xinjie Taigemiao mining area is located on the northeastern edge of the Mu Us Sandy Land.Under the dual influence of climate change and human activities,regional water resources are scarce,and the ecological carrying capacity is nearing its limit,while a large amount of mine drainage remains difficult to utilize effectively.In response to the above issues,the importance of balanced water resource allocation for the integration of blue-green spaces in semi-arid regions is analyzed.Combining regional geological and historical environmental changes,current physical geography,and expected mining subsidence,a fundamental framework for constructing regional blue-green spaces is proposed.Concurrently,through comprehensive research using remote sensing image analysis and statistical yearbook data,the elements and attribute characteristics of blue-green spaces under the regional sandy land-lake-grassland landscape pattern are systematically analyzed.Focusing on the quantity and quality characteristics of mine water and its comprehensive utilization potential,strategies for synergistic blue-green integration to achieve supply-demand balance and enhance ecosystem stability,as well as suggestions for optimizing spatial pattern zoning,are proposed.The aim is to progressively realize the protection and utilization of natural resources,improve the quality of urban and rural living environments,and ensure the safety and stability of the regional ecological pattern,thereby exploring and forming a new model for integrated ecological management and comprehensive resource utilization in semi-arid coal mining areas that aligns mining and land development.

Abstract:To address the challenges of controlling surrounding rock in high roadways subjected to mining-induced pressure,we took the 3924 return air roadway of Zhaiyadi Coal Mine as the research subject.Numerical simulation was used to analyze the influence range of mining pressure on the heading roadway,as well as the distribution characteristics of the plastic zone and maximum shear strain in the surrounding rock during different mining-excavation stages.Based on the shear-block theory of the roadway side coal mass,a mechanical model was constructed,and an expression for calculating the safety factor of the side coal mass was derived.After substituting actual parameters,the influencing factors on roadway stability were systematically analyzed.Combining numerical simulation and theoretical analysis,support parameters for the surrounding rock in the mining-affected section were designed and implemented in a field industrial test.The results show that the influence range of mining stress extends 40～60 m ahead of the heading face,and the distribution of the plastic zone closely aligns with that of the maximum shear strain.The shoulder and floor corners of the roadway sides are the initiation zones for shear failure.Under the superimposed stress from mining and heading,an X-shaped shear-slip zone forms in the pillar side within the mining-affected section,dividing the coal mass into an unstable triangular block.This block slips under the combined action of mining pressure and self-weight,leading to rib spalling,with mining pressure being the direct trigger for activating the shear-slip surface on the pillar side.Roadway height is negatively correlated with side stability,while coal strength and support resistance are positively correlated with side stability.Field monitoring data indicate that after implementing the proposed support scheme,deformation of the surrounding rock in the mining-affected section is limited,and the overall support effect is satisfactory.This study can provide a reference for surrounding rock control in roadways under similar conditions.

Abstract:The intelligent control of coal mines is facing the challenges of dynamic response lag and multi-source data fragmentation,while traditional models are incapable to capture transient anomalies underground and collaboratively analyze multimodal data.We propose a Multi-Task Adaptive Transformer Architecture(MTA-Transformer).Through cross-modal feature fusion and a shared encoder,it unifies the modeling of data such as equipment vibration and gas concentration,achieving multi-scale dynamic perception of the mining environment.This solves the problems of dynamic environmental monitoring and early risk warning.Experiments show that for bearing fault detection,the model achieves an accuracy of 93.5%,a False Alarm Rate(FAR)of 2.0%,and a response time within 5 ms,representing significant improvement over traditional models.For gas concentration prediction,it achieves a Normalized Root Mean Square Error(NRMSE)of 7.83%,a Prediction Interval Coverage Probability(PICP)of 91.7%,and enables early warnings up to 6 hours in advance.The MTA-Transformer provides a practical technical paradigm for the intelligent construction of mines.

Abstract:The mechanisms of water and sand inrush disasters in coal mine roofs are complex,and their prevention and control remain significant challenges.Addressing issues such as inconspicuous disaster precursors,large instantaneous inrush volumes,and difficulties in prediction,this study reviews recent research advances from four key perspectives:hydrogeological conditions,disaster mechanisms,prevention and control technologies,and monitoring and early warning systems.By analyzing typical engineering cases from shallow-buried thin bedrock mining faces,deep-buried weakly cemented rock layers,and faces adjacent to unconsolidated strata,the study clarifies the hydrogeological conditions and disaster characteristics of water and sand inrush,summarizes the essential conditions for its occurrence,and explains the underlying mechanisms in different sedimentary environments.It is emphasized that water and sand inrush results from the combined effects of sedimentary environment and mining-induced disturbance;the former provides the source and dynamic conditions for water and sand,while the latter determines the formation of flow channels and the triggering conditions.Corresponding to three typical inrush modes,prevention and control technologies are discussed,including aquifer modification,conventional dewatering and pressure reduction,surface direct drainage holes,and the"pre-installed diversion pipes+radial drainage"method.Furthermore,based on multi-physics monitoring data collected both underground and on the surface,an intelligent"perception-warning-decision"framework is proposed,forming a comprehensive technical system for dynamic monitoring,early warning,and prevention of roof water and sand inrush in working faces.Future research directions in this field are also outlined.