Abstract:To address the challenges of roof management under the coupled conditions of shallow burial,intense weathering,fractured roof,and valley landforms,we focused on the roof control of 3209 working face in Fengjiata Coal Mine as it traversed a highly weathered zone.Using field measurements,numerical simulation,theoretical analysis,and industrial testing,the stability control technology for surrounding rock throughout the excavation and mining cycle in the shallow weathered zone of the 3209 working face was investigated.The reinforcement effect of grouting cables on the roof during roadway development was evaluated,and the mine pressure behavior mechanism under the coupling effect of surface valley topography and roof weathering in shallow mining faces was revealed.The results indicate that during panel extraction,the maximum vertical stress in the haulage roadway roof reached 2.45 MPa,the maximum roof subsidence was 248 mm,the maximum extent of the plastic zone was approximately 20 m,and the cracks in the roof were predominantly tensile-shear fractures.Under the ravine landform,the maximum surface subsidence above the working face was 1.76 m,the peak front abutment pressure was 5.40 MPa with a stress concentration factor of 1.8.After the mining distance exceeded 80 m,crack development tended to stabilize.A control technical scheme involving grouting"reconstruction"for the highly weathered and fractured roof was proposed to ensure safe mining.Field implementation showed that roof grouting effectively enhanced the overall stability and deformation resistance of the surrounding rock.During the working face extraction,only localized rib spalling and face fall occurred,and the working face advanced smoothly without shield support failure.This effectively resolved the surrounding rock control challenges throughout the excavation and mining cycle in the shallow weathered zone.

Abstract:Monitoring and early warning of spontaneous combustion hazards in goaf are critical preemptive measures for preventing coal fire disasters,representing a core technical challenge in mine fire prevention and control.To address the early warning challenge during the mining of the 1502-2 ultra-thick,steeply inclined longwall top coal caving face in the 5-2 coal seam of Chicheng Coal Mine,programmed temperature rise experiments were conducted.These experiments systematically revealed the evolution patterns of gas concentrations(CO,CO2,CH4,C2H6,C2H4,C2H2)with increasing coal temperature during the spontaneous oxidation of tested coal samples.Based on field monitoring data and indicator optimization,CO and C2H4 were identified as the core predictive indicator gases for spontaneous combustion.Concurrently,ΔCO/ΔO2 and C2H4/C2H6 were selected as key warning indicators.A five-level graded early warning system("Gray,Blue,Yellow,Orange,Red")was established,with specific on-site warning thresholds defined for each level,forming a tailored graded early warning technical system for such working faces.This system was successfully applied at the 1502-2 face,achieving early detection of spontaneous combustion hazards.It effectively enhanced the mine's fire prevention and control capabilities,providing reliable support for safe and efficient mining operations.

Abstract:To address three challenges in classifying coal mine"three violations"text data,including strong domain specificity,semantic ambiguity,and imbalanced sample distribution,a cBert-GCN classification model is proposed.Considering that the coal mine"three violations"texts are short yet contextually coherent and inherently ambiguous,alongside containing domain-specific information,pinyin and glyph embeddings are introduced to enhance text representation.Graph Convolutional Networks(GCN)are applied to"three violations"text classification by constructing text co-occurrence graphs to capture structural information and dependency relationships.The model integrates a Chinese pre-trained model with GCN for feature learning,combining character-level and word-level representations with tunable weights to achieve accurate classification.Experimental results show that the cBert-GCN model outperforms other models,achieving 97.03%accuracy on the training set and 93.17%on the test set,demonstrating strong generalization capability.Thus,the cBert-GCN model shows clear advantages for classifying coal mine"three violations"text data.

Abstract:In the Shenfu Mining Area,the surface is crisscrossed by gullies with large elevation differences.Under the combined action of mining disturbance and surface topography,the laws of mine pressure behavior are complex when the working face advances beneath gully areas.Additionally,the upper coal seam was mined using the room-and-pillar method,and the remnant coal pillars affect the roof stability during the lower seam extraction.To address this issue,taking the 51208 working face of Guojiawan Coal Mine as the engineering background,theoretical analysis,numerical simulation,and field monitoring was combined to investigate the mine pressure behavior laws when mining under room-and-pillar goaf in gully terrain.The results show that:The stress of room-and-pillar coal pillars in gully areas increases toward the extension segment of the slope crest,with the maximum influence position shifting to the middle of the slope,exhibiting the characteristics of"increasing on the slope,decreasing at the slope bottom,stepped distribution,and centripetal offset".Gully terrain dominates the mine pressure behavior of the lower working face,with the difference in roof stress between the working face mined under room-and-pillar goaf being only 1%.The patterns observed in the on-site monitoring of mine pressure are similar to the simulated stress characteristics.The periodic weighting interval in the bottom of the slope area is approximately 7.45 m,while the periodic weighting interval in the uphill section is 9.54～11.74 m.The average periodic weighting interval at the top of the slope and in the stable mining section is 10.0 m.Overall,the mine pressure shows zonal characteristics of"short and small at the slope bottom,chaotic and large in the middle slope,stable and widespread at the slope crest"and a behavior law of"unilateral concentration in the early stage,asynchronous fluctuation in the middle stage,and global stability in the later stage".

Abstract:In order to replace traditional emulsion systems with water hydraulic systems,we highlight the advantages of water-based systems,including environmental friendliness,absence of pollution,and lower operational costs.Leveraging the accuracy and reliability of pressure loss simulation models for pipeline components in AMESim software,simulation models are developed for single-inlet/single-outlet,double-inlet/double-outlet,and triple-inlet/triple-outlet fluid supply pipeline configurations based on the ZY29000/45/100D support hydraulic system.Pressure loss performance is analyzed for these configurations under both emulsion and pure water media.The results show that,under the experimental conditions,the frictional pressure loss in pipelines using pure water is 20%-30%lower than in those using emulsion.As the number of pipeline branches increases,the pressure loss advantage of pure water becomes more significant.However,a comprehensive evaluation is required to balance the stability of the working face in the lifting system with pipeline costs.

Abstract:To address key issues in coal mine intelligentization,such as the lack of a normalized operational management mechanism,underperforming system efficiency,and an immature technology ecosystem,we established a systematic theoretical system and top-level architecture for normalized intelligent coal mine operation.By introducing the integrated concepts of"management integration,system intelligence,sustained operation,and standardized evaluation,"and incorporating a dual-drive model of"intelligent technology+management,"a top-level architecture for normalized intelligent coal mine operation was designed,encompassing business logic,technical systems,data architecture,and evaluation management.The synergistic relationships among the four core systems,including business control,AI collaboration,safety assurance,and evaluation management,were clarified within this architecture.The technical implementation path based on a PaaS cloud foundation,an intelligent operation and maintenance AI engine,and a full-lifecycle data architecture were elaborated.Furthermore,a closed-loop evaluation management process centered on a maturity model was proposed.The results indicate that this top-level architecture provides theoretical guidance and methodological support for achieving long-term stable and self-adaptive normalized operation of intelligent coal mine systems,thereby facilitating the transition of coal mine production toward a safe,efficient,green,intelligent,and sustainable model.

Abstract:To address the"filter cake sandwich"issue in coal slime dewatering using plate-and-frame filter presses,a self-designed plate-and-frame filtration test apparatus and numerical simulation methods were employed.The optimal feeding conditions under current equipment settings were investigated,along with the formation process of the filter cake,filtrate concentration,dewatering rate,particle size distribution of the filter cake,and moisture distribution;the migration patterns of the solid and liquid phases within the filter chamber;and the influence of filter chamber thickness on the internal moisture distribution of the filter cake.The growth behavior of the filter cake and the underlying causes of the"sandwich"phenomenon were also explored.Experimental results indicate the existence of a critical feeding pressure and an optimal feeding concentration.Under these optimal conditions,the filtration time is 8 minutes,with an average moisture content of the filter cake at 23.44%.The filter cake formation process is divided into three stages:base accumulation,structural formation,and internal filling.During the frame filtration process,the"sandwich"phenomenon in the filter cake primarily occurs in the upper-central region of the filter cake,which is the last region to form and the most challenging for filtrate discharge.The particle size distribution of the filter cake is uneven,with coarse particles mainly concentrated at the bottom and central layers,while fine particles are predominantly located in the upper-middle and surface layers.kaolinite and montmorillonite in argillized coal slime can fill the pores of the filter cake structure,this uneven distribution further impedes the discharge of filtrate from the central layer,which is a critical factor contributing to the"sandwich"phenomenon.Numerical simulation results demonstrate that under optimal conditions,both the solid and liquid phases migrate smoothly,allowing for the complete discharge of filtrate from the central region,thereby effectively preventing the"sandwich"phenomenon.However,when the filter chamber thickness increases to 38 mm,the"sandwich"phenomenon begins to manifest and progressively shifts from the feed layer toward the center.As the thickness of the filter chamber increases,the liquid phase volume fraction in the central region increases,leading to significant moisture retention.

Abstract:To address the large deformation of head-on mining roadways under multiple superimposed stress disturbances,we took the 1150403 working face return airway in Hongyi Coal Mine as an engineering case.Combining borehole imaging and numerical simulation,a systematic investigation was conducted on four types of zonal failure characteristics of the test roadway under mining influence,which indicated that the key factors contributing to zonal failure were the high mining-induced stress,the presence of soft rock strata,and unreasonable support structures.Accordingly,a roadway control strategy of"roof-cutting stress adjustment+zonal treatment+grouting reconstruction+multi-level cooperative reinforcement"was proposed,forming a technology of pressure relief and roof-sidewall-floor linkage control.Simulation and field monitoring showed that the after the technology was implemented,the peak stress in the roadway reduced by over 10.29%,the stress concentration area decreased by more than 54.25%,and roof-to-floor and sidewall convergence reduced by 79.2%and 53.8%,respectively,significantly enhancing the surrounding rock control effectiveness.

Abstract:To solve the problems of low transmission efficiency,poor synchronization and low-speed torque pulsation of emerging switched reluctance motor(SRM)in traditional multi-motor drive system of belt conveyor,a multi-motor cooperative control strategy based on optimized fuzzy PID and improved deviation coupling based on Whale Algorithm(WOA)is proposed.Firstly,an integrated switched reluctance semi-direct drive(SRSD)multi-motor system of SRM+built-in planetary gear reduction mechanism was designed;Secondly,a direct instantaneous torque control method based on WOA optimized fuzzy PID was proposed to improve the dynamic response and disturbance immunity of SRM by dynamically adjusting the PID parameters.The simulation results show that compared with the traditional PID and fuzzy PID control,the WOA optimized strategy reduces the speed overshoot to 0.33%and the starting current to 20%under no-load condition;Furthermore,according to the demands of multi-motor cooperative control,a new control structure with improved deviation coupling was designed by introducing synchronous compensation coefficient and acceleration compensation mechanism.The simulation shows that the maximum speed difference of the three motors decreases from 4 r/min to 3 r/min;Finally,a validation test was carried out on the semi-direct-drive test platform with two rollers and three motors of the belt conveyor,and the maximum speed difference between the three motors in the no-load and load tests of the drive system with the new control strategy was 3.8 r/min and 3.4 r/min respectively.

Abstract:To address the issue in steeply inclined coal seam mining where the layout of negative coal pillars in roadways,while effective in avoiding rockburst,tends to create air leakage channels with surrounding goaf and subsequently induce spontaneous coal combustion,the 412W working face of Huafeng Coal Mine was taken as the research subject.We systematically analyzed the mining characteristics and spontaneous combustion risks in the goaf of steeply inclined faces with negative coal pillars.Using a combined approach of field observation and numerical simulation,we investigated the multi-physical field coupling among temperature,pressure,and gas concentration in the goaf,accurately delineated spontaneous combustion hazard zones,and ultimately proposed a targeted prevention and control strategy for such mining conditions.Results show a significant pressure difference exists between the intake and return sides of the goaf,promoting air leakage channel development.Connectivity with adjacent goaf further expands the leakage scope.Major leakage zones are concentrated between supports of the 412W working face and at the return airway corner,with an air leakage rate of approximately 146.56 m3/min from the rear goaf into the working face,and about 78.76 m3/min from the goaf of 411W working face into the upper gate road of the 412W working face.Based on these findings,an integrated prevention system combining high-level borehole injection of composite gel and cyclic nitrogen injection into the goaf was established.Through the dual mechanisms of oxygen isolation/sealing and inerting/cooling,this system effectively curbed the spontaneous combustion hazard,providing technical support for safe mining in steeply inclined faces with negative coal pillars.

Abstract:To address the challenge of rockburst prevention in development headings under the coupled effects of large mining depth,fault structures,and lateral stress from goafs,we employed a combined approach of theoretical analysis,field measurement,and engineering back-analysis.We systematically investigated the mine pressure behavior in development headings and proposed comprehensive rockburst prevention measures of"drilling-blasting+reverse heading advancement+targeted reinforcement support,"achieving safe excavation in areas of coupled high stress concentration.The research results show that,based on estimates from the"three-zone loading"theory,the maximum static load on the development heading is 45.67 MPa,and the peak lateral abutment pressure from the goaf is located 60 m from the goaf.Microseismic monitoring data indicate that microseismic events mainly occur within 30 m of the roof and floor.Microseismic events within 30 m from the roof account for 40%of the total energy and 38%of the frequency.This horizon primarily corresponds to a 13.4 m thick medium sandstone located 23.6 m above the coal seam roof,providing a basis for optimizing roof fracturing parameters guided by key strata theory.The back-analysis results of microseismic data show stress accumulation at 55～80 m from the 3lower101 goaf,which is generally consistent with the 60 m peak location calculated by the three-zone loading theory.

Abstract:During the horizontal sublevel mining of steeply pitching coal seam groups,multi-sublevel extraction leads to complex roof movement and stress evolution.To investigate the fracture characteristics and stress evolution mechanisms,based on the engineering background of Tianshun Mine in Xinjiang,we combined physical similarity simulation and numerical calculation to analyze the asymmetric failure characteristics of surrounding rock and the energy-stress synergy mechanism.The results indicate that the mining-induced stress field exhibits significant asymmetric deflection.Stress concentration zones form in the upper and lower parts of the goaf roof along the dip,with a stress relief zone in the middle.The third principal stress deflects reversely,forming an asymmetric stress envelope arch.The surrounding rock failure evolves in three stages:sublevel 1 and sublevel 2 represent the initial stable stage,with minor principal stress deflection and slight rock caving.Sublevel 3 is the critical instability stage,where principal stress deflection increases markedly,both microseismic energy and unloading volume peak,the bearing arch undergoes abrupt instability,and high-position strata experience intense caving.Sublevel 4 and sublevel 5 constitute the chain propagation stage,characterized by an expanding unloading scope and increased microseismic frequency,with the failure range extending as the mining deepens.The study reveals that roof stability is synergistically controlled by the mining technique and principal stress deflection.The roof becomes unstable in stages at a sublevel height of 25 m,with the third sublevel acting as the critical threshold.

Abstract:To address technical issues associated with traditional integral active drill rods,such as complex assembly and disassembly,low replacement efficiency,the need for complete replacement due to wear,and high replacement costs,a detachable active drill rod was developed.By thoroughly analyzing the fundamental requirements of the drill rod,a technical solution based on a split structural design was proposed,along with a method for determining the optimal filling amount of thread-locking adhesive.Through simulation and numerical analysis of thread-locking adhesive failure parameters,the relationships among applied torque,maximum contact pressure,and maximum contact torque were investigated,leading to the determination of the applied torque value at which the thread-locking adhesive fails.This provides data reference for reducing experimental testing frequency and lowering experimental costs.Finally,laboratory testing,field drilling trials,and underground mine experiments were conducted.Results of the underground trials demonstrate that the active drill rod operates continuously and stably during drilling,with no unsafe occurrences such as thread disengagement,jamming,deformation,or fracture.It meets the requirements for applicability,safety,strength,and stability in underground applications.Worn components can be individually replaced without the need for complete rod replacement,facilitating convenient and efficient assembly/disassembly and significantly reducing replacement time and costs.

Abstract:To address the critical challenge of water and sand inrush from loose layers in coal seam roof areas with thin bedrock,we systematically analyzed the four essential conditions for such disasters:water-sand source,transport pathways,driving forces,and accommodation space.Accordingly,a water displacement and sand consolidation grouting treatment technology was proposed.Its core principle involves reconstructing the hydrodynamic field of the loose layer through high-pressure grouting to form a spatially interconnected"root skeleton"network that extends vertically and interlocks horizontally.This achieves the dual objectives of displacing water from the loose sand layer and reinforcing stratum stability.Based on this concept,targeted drilling type selection criteria and key parameters were established for different hydrogeological conditions.The applicability of four grouting modes—Flat-Pushing,Central Blooming,Cap Covering,and Edge Locking—was clarified,along with the key supporting parameters such as grouting materials,pressure,and volume.According to the field application at Wugou Coal Mine,after treatment,the maximum specific yield of the sand layer in the Quaternary aquifer decreased to 0.000474 L/(s·m),and the grouting pressure in inspection holes increased by 15.3%～57%compared to pre-treatment levels.Multi-dimensional data,including characteristics of grout return via inter-hole communication,monitoring of grout diffusion distance,and borehole core sampling results,collectively confirmed the effective formation of the"root skeleton"grout diffusion network.This significantly reduces the risk of water-sand inrush disasters,providing a systematic solution integrating concept,technology,and parameters for preventing and controlling water hazards in loose layers within coal seam thin bedrock zones.

Abstract:To promote energy saving and emission reduction in coal mine explosion-proof vehicles,the advantages of diesel engines(easy starting and reliable continuous operation)and electric motors(zero exhaust emissions and low noise),are leveraged to develop a parallel oil-electric dual-power drive technology.The diesel engine and electric motor are designed to operate in a time-sharing mode.The key technologies are elaborated.For the explosion-proof diesel engine and DC trolley electric parallel drive,the onboard current collection device,high-voltage DC electric drive system design,matching of explosion-proof diesel engine with hydro-mechanical transmission,matching of explosion-proof electric motor with power-shift transmission and drive axle,and real-time vehicle monitoring system design are introduced.For the explosion-proof diesel engine and AC cable electric parallel drive,the onboard integrated automatic cable winding device,high-voltage AC electric drive system design,matching of explosion-proof diesel engine with hydraulic pump and motor,and matching of explosion-proof electric motor with hydraulic pump and motor are introduced.Tests show that the parallel drive system combining an explosion-proof diesel engine and a DC trolley electric motor achieves an energy consumption ratio of approximately 6∶1 for the two power sources,while the latter can reduce the required number of auxiliary transport equipment and operators by one-third.For the parallel drive system combining an explosion-proof diesel engine and an AC cable electric single-boom roof bolter,energy consumption can be reduced by about 20%,with exhaust emissions decreasing by one-third and equipment vibration and noise lowered by 50%for the latter.

Abstract:To enhance the safety and reliability of the artificial ground freezing method,we compared the mechanical performance differences of freezing pipes with outer and inner lining welded structures under varying specifications and low-temperature conditions,and clarified the influence of their load-bearing capacity and deformation characteristics on the engineering selection.We adopted two types of freezing pipes with different welding methods,namely inner lining and outer lining.Three specifications,namely Φ140 mm×5 mm+Φ140×6 mm,Φ140 mm×6 mm+Φ140 mm×6 mm,Φ140 mm×5 mm+Φ140 mm×5 mm,were selected respectively.Under simulated low-temperature conditions,their axial load-bearing capacity and flexural deformation characteristics were tested.The results show that under the same dimensions and experimental conditions,the average load-bearing capacity of freezing pipes with external lining structures is significantly lower than that of pipes with internal lining structures,while their deflection values are higher.This indicates that the welding structure directly influences the mechanical properties of freezing pipes:internal lining structures exhibit superior compressive resistance,whereas external lining structures demonstrate stronger deformation adaptability.Safety assessments of freezing pipes with the two different welding methods were conducted using the curvature test method,and the results indicate that both types meet the requirements of safety codes.

Abstract:To address poor power quality under complex operating conditions in underground coal mines,we investigate methods for detecting and compensating abnormal currents.The structural principles and functional characteristics of various types of second-order generalized integrators are analyzed in detail to achieve accurate current tracking and effective filtering.Furthermore,an integrated current compensation method is proposed.Based on the second-order generalized integrator structure for fundamental frequency filtering,the positive-sequence current component is extracted using the symmetric component method,and the active current component is extracted using the instantaneous power theory.The fundamental positive-sequence active component of the load current is then uniformly obtained,and the difference between the actual load current and this component is taken as the total compensation requirement,enabling integrated current detection and compensation.Simulation experiments under various non-ideal load conditions are conducted on the Simulink platform to verify the accuracy of the theoretical analysis.The results demonstrate that this method can achieve integrated detection and compensation of abnormal currents such as reactive power,harmonics,and imbalance,proving its feasibility for power quality management in complex underground coal mine environments.

Abstract:As the mineral processing industry transitions towards intelligence and efficiency,fuzzy control technology has become a core research direction for technological advancement in this field due to its superior ability to handle nonlinear,multivariate,and uncertain systems.To understand the research progress in the application of fuzzy control technology in the mineral processing industry,we focus on analyzing its practical effectiveness in key processes such as grinding and classification,flotation,and dense medium separation.Research shows that multivariate fuzzy control systems effectively alleviate coupling issues between variables through methods such as decoupling modeling,"dual-input single-output"design,and fuzzy neural networks.The integration with neural networks(e.g.,fuzzy"feedforward-feedback"strategies,fuzzy neural network controllers)significantly improves control accuracy and robustness.Composite control technologies(e.g.,fuzzy PID,PLC integration)optimize system adaptability,addressing bottlenecks such as fixed parameters and strong hysteresis in traditional industrial control.Furthermore,the application of intelligent algorithms(e.g.,weighted WM algorithm,case-based reasoning combined with RBF networks)in fuzzy rule extraction,as well as improvements in system stability through techniques such as variable universe control,sliding windows,and APSO algorithms,further enhance the engineering applicability of fuzzy control.In the future,fuzzy control systems will be fully integrated with the entire mineral processing workflow,including flotation,gravity separation,and magnetic separation,assisting the intelligent and high-efficiency development of the mineral processing industry.

Abstract:In response to the complex factors affecting the stability of roadway surrounding rock,based on the field investigation background of Baliancheng Coal Mine,we adopted fuzzy cluster analysis method to study eight main factors affecting the roof strength,two-wall strength,floor strength,buried depth,roof-to-height ratio(ratio of direct roof thickness to mining height),coal pillar width,maximum horizontal principal stress and average caving interval,and established an evaluation model.The surrounding rock of the roadway was divided into five evaluation grades:very stable(Ⅰ),stable(Ⅱ),moderately stable(Ⅲ),unstable(Ⅳ)and extremely unstable(Ⅴ).The regression equation of surrounding rock stability prediction was established using multiple stepwise regression analysis.The results show that the accuracy of the simulation is 0.911,which can well reflect the quantitative relationship between the main influencing factors and the surrounding rock stability.The stability identification software of the surrounding rock of the roadway was developed,which could quickly identify the type of roadway,thus to design the optimal support scheme based on the classification results,and effectively reduced the deformation of the surrounding rock.

Abstract:To address issues such as energy waste,response lag,and operational instability caused by fixed speed settings in traditional speed control methods for belt conveyors,we proposed a dual-loop fuzzy PID speed control strategy based on the dynamic balance between coal flow and motor power.Based on the longitudinal dynamic model of the conveyor belt and the coal flow-motor coupling equations,the system equilibrium conditions and constraints were derived,and three typical operating modes—safe,efficient,and transitional—were defined,revealing the strong nonlinear relationship among belt speed,coal flow,and motor power.A hierarchical dual-loop fuzzy PID control architecture was constructed,comprising an outer-loop fuzzy controller and an inner-loop PID controller.The outer-loop fuzzy controller takes real-time coal flow and motor power as inputs and dynamically generates speed setpoints using Mamdani fuzzy rules,enabling adaptive energy efficiency optimization across the three operating modes.The inner-loop PID controller precisely tracks the speed setpoint via feedback,effectively suppressing dynamic fluctuations.Experimental results demonstrate that this strategy enhances system dynamic response,achieving a setpoint update delay of less than 5 ms under step changes in coal flow,an actual speed response time of only 1.2 s,a speed tracking root mean square error of 0.09 m/s,and an efficient operating mode proportion of 89％,significantly improving system energy efficiency and control accuracy.