Taking the engineering background of the Baiyanzi Mine design in Gansu Province, and based on the occurrence characteristics of steeply inclined coal seams, the layout system of mine development roadways was innovated by following the principle of adapting measures to local conditions. By introducing mature domestic coal mining technologies and equipment, the underground mining system was optimized, reducing roadway engineering quantity and investment costs. This realized the intensive design of the production system, effectively lowering mine construction costs, significantly improving the level of mechanical mining, and enhancing the production capacity of working faces, thus providing technical guarantees for safe and efficient mine production.After commissioning, the mine exhibits the characteristics of a modern mine with "streamlined personnel configuration, outstanding production efficiency, advanced technical equipment, and remarkable economic benefits", integrating both economic and social benefits. As a pilot development project for steeply inclined coal seams in the Baiyanzi Mining area of Gansu Province, its construction has accumulated valuable engineering experience for the subsequent large-scale development of steeply inclined coal seams under similar geological conditions.

Cantilever beam structure is a type of overlying strata structure commonly found in comprehensive mining working face, which often results in higher stress concentrations in the coal pillar near the mining stop line. The failure of coal pillar leads to the transfer of front abutment pressure to the main roadway, thereby increasing the risk of destabilization of the surrounding rocks in the main roadway. Taking the 22104 working face of the Yaping Coal Mine as the engineering background, this paper first analyzes the transfer process of front abutment pressure influenced by the cantilever beam structure based on key stratum theory. Subsequently, the deformation and failure processes of the surrounding rock in the main roadway under the gradual influence of mining were simulated using FLAC^3D, which reduces the width of the coal pillar to about 55m. In order to provide sufficient safety redundancy for the main roadway, a combined reinforcement technology consisting of “excavating another pressure relief roadway and pre-grouting reinforcement on both sides” is proposed, which simultaneously realizes the pressure relief by the roadway and the pressure control by the reinforcement of the coal and rock, so as to improve the stress environment of the main roadway. The deformation and failure of the main roadway under the two programs of “pressure relief” and “pressure relief-pre grouting” were simulated, and the results showed that the reinforcement technology can effectively reduce the risk of failure of surrounding rocks in the main roadway. The program was applied in the field, and the main roadway could still maintain its own stability after 3 months of mining stoppage, which provided a guarantee for the safe mining of the mine.

Transparent working face model is an important prerequisite for achieving safe and efficient production in coal mines, and it is of great significance for realising accurate coal mining and geological safeguard. Taking the working face of a mine under complex geological conditions as an example, the research on transparent working face model construction technology and system for intelligent mining is carried out. Firstly, the self-developed Transparent Mine 3D Geological Modelling System (TIM-3D for short) is introduced, which provides an excellent solution for complex geological modelling by virtue of its unique development concept and advanced algorithms. Secondly, the TIN-GTP algorithm and implicit iterative modelling technique were proposed to successfully solve the challenges faced during the construction of inverse faults. Subsequently, a transparent working face model was constructed using the TIM-3D system to visualise the spatial morphology and spreading pattern of the strata, rock seams, coal seams and their tectonics 50m above and below the No.9 coal seam. The transparent working face model not only provides accurate geological navigation for intelligent mining, but also realises mutual information feedback with the ‘three machines’, which further improves the level of intelligence.

Based on the development trend of the survey and design industry, this article analyzes the problems existing in the promotion of BIM technology in coal design enterprises, and proposes a construction route for enterprise level BIM technology application system from the aspects of organizational structure setting, technical team construction, software and hardware configuration, project implementation and application, enterprise family library and model library, standards and guidelines, and guarantee measures, with technical team construction as the foundation and focus, and project implementation as the starting point. Through 4 years of construction, the comprehensive popularization of BIM technology among young and middle-aged design employees has been basically achieved. BIM technology has been deeply applied in the design and engineering general contracting of feasibility studies in mines, underground cooling system and coal storage and blending bases, accumulating a professional library and organizing design process and experience into enterprise standards and guidelines, provides a platform for promoting BIM technology within the enterprise.

With the continuous acceleration of coal mine intelligentization and informatization, industrial control systems (ICS) are increasingly confronted with complex cybersecurity threats, particularly the emergence of high-frequency and large-scale cyberattacks as a prominent challenge. Traditional protection schemes often rely on hardware-based detection devices and passive defense mechanisms; however, they commonly suffer from significant drawbacks such as strong intrusiveness, delayed responsiveness, and insufficient traceability. These limitations make it difficult to satisfy the stringent security requirements of coal mine ICS, where both real-time performance and operational stability are equally critical. Against this backdrop, digital twin technology, with its unique capabilities of virtual-physical mapping and synchronized interaction, provides a novel approach to enhancing cybersecurity in coal mine networks. This paper first reviews the current security landscape of coal mine ICS and, in light of recent advances in digital twin models, analyzes their potential applications in cybersecurity. An experimental system is then constructed on the OpenPLC platform, and empirical tests are conducted to assess the security vulnerabilities of the Modbus protocol, thereby validating the effectiveness of digital twin technology in offensive–defensive security scenarios. Finally, the study further explores the practical implementation challenges and future development directions of digital twin applications in coal mine contexts.

Aiming at the problem of reasonable selection of coal pillar width in gob-side entry driving technology under the condition of secondary gob-side entry driving, taking the roadway layout and engineering geological conditions in Qianyingzi Mine as the background, theoretical analysis, numerical simulation and field engineering practice were adopted to study the gob-side entry. The theoretical width range of coal pillar is calculated by the limit equilibrium theory of coal pillar, and the distribution characteristics of surrounding rock stress and displacement of gob-side entry under the width of 4 m~8 m coal pillar are analyzed by numerical simulation. The research shows that the reasonable width of coal pillar is 4 m~8 m； under this geological condition; When the coal pillar size is 5 m~7 m, the stress of coal pillar is improved. It can ensure the stability of roadway while giving consideration to economic benefits to a great extent; Based on all the factors, it is determined that the reasonable coal pillar for gob-side entry driving in E3215 wind tunnel is 6 m. When the small coal pillar is supported by anchor and cable, the maximum deformation of the roof and floor and two sides of E3215 air roadway after delayed grouting is 154 mm and 196 mm respectively, and the overall deformation of the roadway is within the controllable range. The 6 m coal pillar and surrounding rock control technology of gob-side entry driving can realize the stability of double-lane coal pillar and long-term effective control of surrounding rock.

To study the surrounding rock stability and control technology for gob-side retention entries with paste backfilling in working faces, this research takes the CT301 backfilling working face of a mine in the Ordos Mining Area as the engineering background, and conducts analysis and research through theoretical analysis, numerical simulation, and on-site industrial experiments. First, based on the equivalent mining height theory, the overlying rock movement characteristics of gob-side retention entries with paste backfilling are analyzed. A mechanical model of the roof is established under the assumption of the Winkler elastic foundation beam, clarifying that the filling ratio is a key controllable factor affecting roof deflection. Increasing the filling ratio can effectively enhance the supporting role of the backfill for the overlying rock. Second, the FLAC3D numerical simulation is used to study the deformation of surrounding rocks and the manifestation of mining pressure in gob-side retention entries with paste backfilling in working faces. The results show that a higher filling ratio leads to weaker mining pressure manifestation and better surrounding rock stability. As the working face advances and the solidification strength of the paste backfill increases, the supporting pressure in the stope gradually stabilizes. Finally, a comprehensive control technology system of "basic bolting-mesh-cable support + local collaborative strengthening support with portal hydraulic supports" is proposed. The on-site application results indicate that this technology effectively controls the deformation of surrounding rocks in the entry, with the maximum deformations of the roof-floor and two sides stabilizing at around 190mm and 140mm, respectively, demonstrating significant control effects on the surrounding rock of the retained entry.

The mining roadway of Panel 232206 in Meihuajing Coal Mine is located near a fault zone where the surrounding rock is subjected to typical combined effects of mining-induced stress and fault tectonic stress. Under these conditions, the mining roadway is prone to deformation and failure, with distinct variations being observed in surrounding rock deformation at different stages. To address the deformation and failure issues of the mining roadway, the UDEC numerical simulation method is first employed to investigate the rational width of fault-protection coal pillars. The activation characteristics and patterns of faults under different protection pillar widths are obtained. When the fault-protection coal pillar is less than 50m during mining operations at Panel 232206, fault activation is observed. It is found that as the pillar width decreases, the vertical displacement near the fault gradually increases while its affected range reduces, indicating that fault activation becomes more pronounced and occurs at lower positions with decreasing pillar width. The vertical stress at the fault with 60m protection pillars is measured to be 34.5% lower than that with 30m pillars. The cusp catastrophe theory is then applied to analyze the relationship between the plastic zone and the width of fault-protection pillars. The rational width of fault-protection pillars is determined when the ratio of pillar width to unilateral yield zone width reaches 1.5. Based on field data, the calculated optimal width for fault-protection pillars is 51.66m. Finally, based on studies of deformation patterns under different fault-protection pillar widths, a control technology combining pressure relief and support is designed for the transportation roadway of Panel 232206. Comparative experiments are conducted to verify the control technology. Monitoring data from both test and control sections demonstrate significant improvement in roadway deformation control, with an average reduction of 58.55% in deformation. These results confirm the effectiveness of the current support measures in successfully controlling surrounding rock stress.

Focusing on the instability issues of semi-coal rock roadway ribs in deeply buried inclined coal seams under high stress and mining disturbance, this study takes the gob-side entry retaining of 2301 working face in Shanxian Fengyuan Coal Mine as the engineering background. Through theoretical analysis, numerical simulation, and field tests, the failure mechanism of semi-coal rock roadways was investigated, leading to the development of a collaborative control scheme integrating "roof-cutting pressure relief + cross-layer surface reinforcement support". Results indicate that compressive-shear failure in coal mass and shear slip failure at coal-rock interfaces constitute the primary causes of roadway rib instability. Effective control measures involve 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 (φ_s). 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 semi-coal rock roadway convergence, effectively restraining rib deformation in mining roadways.

The fracture propagation effect in thick-hard roof strata during hydraulic fracturing is critically significant for evaluating the technology's effectiveness in preventing rock bursts. Using the hydraulic fracturing operation in the thick-hard roof strata of the 20101 working face as an engineering case study, this research investigated the fracture propagation effect through surface microseismic monitoring and the small-volume covering ellipsoid method. The results demonstrate that: ①A total fracture length of 1,000 m was achieved, with 1,255 microseismic events monitored during hydraulic fracturing. The fracture propagation range exhibited a positive correlation with fracturing fluid consumption but showed no correlation with operation duration. As microseismic events increased, the fracture propagation range in thick-hard rock strata expanded;② Centered on the horizontal well, hydraulic fractures demonstrated average radii of 127 m (north-south direction) and 31 m (vertical direction), with an average width of 71 m (east-west direction). The stimulated reservoir volume (SRV) in thick-hard rock strata reached 371.2×10⁴m³ post-fracturing；③ Water discharge conditions at underground drainage borehole drilling sites showed good agreement with fracture propagation results detected via surface microseismic monitoring.These findings confirm that surface microseismic monitoring technology can effectively study fracture propagation effects, providing a scientific basis for evaluating both fracture propagation outcomes and rock burst prevention effectiveness in thick-hard roof strata hydraulic fracturing.

To investigate the dynamic response characteristics of tunnel roof under mining-induced seismicity, a simplified model of the rock strata-support system’s dynamic response under impact disturbance was established. The dynamic responses of rock layers at different locations were studied under various conditions. The influence of impact disturbances, segmented rock layers, and changes in stiffness at different locations on the dynamic response of strata under conventional support was analyzed. Additionally, the effect of energy-dissipating support and damping changes on the dynamic response of the strata was discussed. The results show that the peak displacement of the strata response is proportional to the square root of the disturbance energy and linearly related to the initial velocity of the top layer. When the sandstone block above the coal seam is divided into seven parts, the peak displacement responses of m1 and ms decrease by 32.3% and 34.0%, respectively. Increasing ki by five times and ks by 25 times results in a decrease of 60.5%, 68.4%, and 81.1% in the peak displacements of m1, ms, and m7, respectively. The use of an energy-dissipating support with a stiffness of cs = 212.5×105 N/(m/s) and an increase in ci by five times shortens the dynamic response time of the strata to 1.35 seconds. Therefore, appropriately altering the rock layer structure, enhancing the support stiffness, and using energy-dissipating supports can effectively reduce the dynamic response of the strata induced by mining-induced seismicity and increase the stability of the strata.

Abstract：To address the insufficient dust control in traditional Long-duct forced and short-duct exhaust ventilation system within fully mechanized excavation faces， the study proposes a novel ventilation and dust removal system incorporating a flow distribution device. Through three-dimensional numerical modeling combined with Fluent simulations and field measurements， the mechanism of airflow field regulation and dust migration control is systematically investigated. The gas-solid coupling process is simulated using a heterogeneous Eulerian multiphase model with Realizable k-ε turbulence modeling， while a mathematical model of flow distribution ratio based on modified Bernoulli equations is established. Five pressure-exhaust ratios (3：2 to 2：3) are comprehensively evaluated through entropy weight method. Results demonstrate that the flow distribution device generates a gradient pressure field with terminal positive pressure and heading negative pressure， creating directional airflow to suppress dust diffusion. The optimized system reduces rear-tunnel dust concentration from 116.5 mg/m3 to 8.3 mg/m3. Under the 5：4 pressure-exhaust ratio (700m3/min supply /560m3/min exhaust)， dust removal efficiency reaches 96.5% with 59.81% reduction at operator position， achieving the maximum entropy weight value of 22.2%. Pressure field analysis confirms effective elimination of vortex-induced dust agglomeration. The research establishes an optimization model integrating structural parameters of flow distribution device and pressure-exhaust ratio matching， providing an innovative solution for directional dust control in mine environments. Key Words：flow distribution device; long-duct forced and short-duct exhaust ventilation system; pressure-exhaust ratio; numerical simulation; dust control efficiency

During the excavation of deep coal roadways, affected by high in-situ stress, abnormal stress in the roadway surrounding rock can easily induce disasters such as coal bumps, roof falls, and rib spalling. Accurate positioning and monitoring are the prerequisite and foundation for preventing and controlling these disasters. Taking the deep excavated coal roadway in Zhaozhuang Coal Mine as the engineering background, a highly sensitive high-frequency microseismic positioning and monitoring system was established. To address the challenge of identifying complex and weak microseismic signals induced by coal roadway excavation, a denoising algorithm based on unsupervised deep learning and attention mechanism was introduced, achieving adaptive suppression of broadband noise. Based on the improved ELM intelligent algorithm, accurate and efficient picking of weak microseismic events was realized. The Hilbert-Huang Transform (HHT) time-frequency analysis method was used to deeply analyze the time-frequency characteristics of three typical microseismic waveforms, namely small-energy, large abnormal stress-energy, and coal bump waveforms, realizing accurate identification of complex microseismic waveform signals induced by coal roadway excavation. On this basis, the source location of coal bump events induced by abnormal stress was carried out, and the characteristics of the microseismic monitoring response law were analyzed, revealing the coupling law between the microseismic monitoring response characteristics of "precursory rise - peak mutation - attenuation and stabilization" and the dynamic evolution process of "stress accumulation - coal bump occurrence - stress release" during the excavation process. The research results provide effective technical support for the early identification and early warning of surrounding rock damage and catastrophes during the excavation of deep coal roadways.

The strong dynamic load caused by the hard roof breaking and the high stress superposition caused by the large buried depth during the mining process of the working face are the main causes of the rock burst, and the filling mining is an effective means to control the roof breaking. In order to explore the control effect of filling mining on the dynamic and static load source of rock burst, the evolution law of roof breaking height and the distribution characteristics of abutment pressure under different filling rates were studied by theoretical calculation and field monitoring. The classification prevention and control technology of rock burst for filling mining was put forward, which was applied in the deep hard roof working face of Gucheng Coal Mine, and the anti-impact effect was tested by on-site microseismic monitoring. The results show that there is an optimal filling rate in the filling face and after reaching the optimal filling rate, the movement mode of the hard roof changes from periodic breaking to bending sinking, which greatly reduces the dynamic load of the roof breaking, and the reduction of the roof breaking height reduces the peak value of the abutment pressure. The 1123 working face of Gucheng Coal Mine did not reach the optimal filling rate, and the measures of pre-splitting blasting of hard roof, top coal support, high-pressure grouting of thick top coal and large-diameter drilling were taken. The 1 # working face reached the optimal filling rate, the blasting roof breaking pressure relief measures were cancelled, and only the large diameter drilling of coal body and the pressure relief measures in special areas were adopted. After the pressure relief measures were taken in the two working faces, the filling rate of the 1123 working face gradually increased from 70 % to 90 %, and the microseismic events of the roof of the working face changed from “low frequency and high energy ” to “high frequency and low energy ” ; the roof microseismic events of 1 # working face are characterized by “low frequency and low energy ”. The research results can provide theoretical guidance for the mining and anti-impact technology of hard roof working face in rock burst mine.

Studying on gas desorption law about measuring coal seam gas content by compressed air sampling and exploring calculation method of losing gas quantity contribute to improving the accuracy of measurement result. At first, the gas desorption experimental device was designed and manufactured which can simulate measuring coal seam gas content by compressed air sampling. Afterwards, optimum experimental parameters of coal size and driving air pressure and gas desorption law about measuring coal seam gas content by compressed air sampling in different conditions were studied by experiment. Finally, the mechanism that compressed air driving promotes gas desorption of coal was analyzed, and the correction method of losing gas quantity inferred value was presented, and field test and application were carried out. The results show that compressed air driving may influence on coal specimens containing gas from vibration effect, fragmentation effect and dilution effect, and it may promote gas desorption of coal. On the border of compressed air driving desorption early stage and follow-up static atmospheric pressure desorption, there is a clear inflection point in the rising curve of accumulated gas desorption quantity. The relative error is 24.2%-61.8% between losing gas quantity inferred value determining by gas desorption law of follow-up static atmospheric pressure and actual value of gas desorption quantity in the compressed air driving period early stage. The revised relative error descends to 1.5%-14.0%, and the measurement result of coal seam gas content is improved by 3.72%-6.86%.

To meet the demands of underground production, material shafts, and chambers have become crucial sites for mine material supply. The material shaft and conveying process significantly influence gas migration in underground chambers, particularly in high-gas mines. To investigate the impact of material shaft construction and conveying operations on the airflow-methane distribution characteristics within the chamber, this study established a coupled airflow-methane diffusion physical model by incorporating a methane component via the species transport model. The effects of material transport on the airflow-methane distribution in the material chamber and shaft were examined. The findings demonstrate that prior to shaft construction, localized methane accumulation occurred in the chamber due to insufficient airflow. After shaft construction, airflow enters the chamber along the shaft under pressure differentials, forming vortices that reduce overall methane concentrations. However, methane accumulation (exceeding 0.09% by volume) persists in the chamber's upper corner. As the methane content in the system airflow increases, the dispersing effect of pressure differentials diminishes. Compared to pressure-driven dispersal, increasing system airflow velocity more effectively reduces methane concentrations in the upper corner, with enhanced effectiveness at higher velocities. 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. These findings provide valuable insights for ventilation design in material shafts and chambers.

Rock slopes in open-pit coal mines are subjected to the long-term coupled effects of freeze-thaw cycles and cyclic loading-unloading. To further understand the impact of freeze-thaw weathering on sandstone damage from an energy analysis perspective, stepped cyclic loading-unloading tests were conducted on red sandstone specimens subjected to 0, 20, 40, and 60 freeze-thaw cycles. The freeze-thaw damage to the specimens was quantified using the wave velocity reduction rate and the porosity growth rate. The energy density per cycle and acoustic emission energy during the cyclic loading-unloading tests were then calculated and analyzed. The results indicate that: (1) The damage to the red sandstone intensified with increasing freeze-thaw cycles. After 60 cycles, the wave velocity decreased by 50.83% and the porosity increased by 34.75%. (2) The fatigue stress-strain curves of the red sandstone specimens exhibited a "sparse-dense-sparse" trend. The fatigue strength decreased from 80 MPa? for the unfrozen-thawed state to 40 MPa after 60 freeze-thaw cycles. (3) The total energy density and elastic energy density of the red sandstone specimens showed a "step-like" increase with rising cyclic loading-unloading levels. Prior to fatigue failure, the majority of the input energy was converted into elastic energy, while the dissipation energy fluctuated within a relatively small range. (4) The characteristics of the acoustic emission energy time series can effectively characterize the failure process of red sandstone under the coupled action of freeze-thaw cycles and cyclic loading-unloading. The overall level of acoustic emission energy increased sharply before the instability and failure of the red sandstone occurred. (5) Pre-existing damage induced by freeze-thaw cycles exacerbated microcrack propagation in the red sandstone specimens during the initial stages of cyclic loading-unloading, making damage accumulation more prone to occur. These findings provide a theoretical foundation for assessing and preventing the long-term stability of red sandstone slopes in open-pit coal mines located in cold regions.

To address the challenge of balancing detection performance and real-time capability under complex factors in coal mine environments, such as noise, multi-scale targets, and occlusion, this paper proposes a lightweight and high-precision foreign object detection method for underground conveyor belts based on an improved YOLOv11. Firstly, building upon YOLOv11, a dynamic convolution module integrating multi-path channel attention (DCNv2-Dynamic) is introduced to replace the standard convolutions in the C3k2 blocks of the backbone network, enhancing the capture of critical features in complex scenes. Secondly, a 160×160 detection layer is added to strengthen small object perception, while the redundant 20×20 output layer is removed to reduce computational load. Furthermore, a Separate and Enhance Attention Module (SEAM) is embedded into the detection heads to mitigate the information loss caused by occlusion. Experimental results show that the improved model achieves significant performance gains, achieving a 3.7% improvement in mAP50 and a 10.8% improvement in mAP50:95, alongside a 26.2% reduction in computational cost and a 21.8% reduction in model size, thereby establishing an efficient and reliable solution for foreign object detection in coal mine conveyor belts.

To address the reliance of shearer gearbox oil maintenance on manual experience and the difficulty of quantitatively evaluating multi-feature data, a multi-feature data-driven oil maintenance decision system is developed. The system integrates oil temperature, physicochemical indicators, and ferrography detection data, extracting 14 characteristic parameters, and proposes three key technologies: (1) a wear trend recognition method based on recurrent neural networks (RNN), which employs a sliding window to capture temporal dependencies; (2) a wear stage classification method based on bidirectional gated recurrent units (Bi-GRU), which learns bidirectional temporal relationships of features; and (3) fault analysis and recommendation by combining a three-level quantitative scale with hierarchical logical reasoning, establishing associations between degradation parameters and maintenance suggestions. Experimental results show that the RNN-based wear trend recognition achieves an accuracy of 90.7%, and the Bi-GRU-based wear stage classification reaches 91.49%; field validation demonstrates consistency with expert opinions. Furthermore, test bench experiments confirm the system’s generalization capability. The proposed system effectively integrates multi-source heterogeneous data, enabling intelligent recognition of shearer gearbox wear states, fault analysis, and maintenance recommendations, thereby significantly reducing reliance on manual experience and improving the objectivity and reliability of maintenance decision-making.

In order to address the problem that helical gears of mine-used vibrating screen exciter is prone to wear and and seriously affects the coal washing process, this paper establishes a dynamic numerical simulation model of the coupling system between the helical gear and rotor of the vibrating screen exciter. The fourth order Runge Kutta method is used to solve the time-varying meshing force of the gear. The characteristics of gear wear under mixed elastohydrodynamic lubrication is analyzed. By combining the above methods, the vibration response of the exciter helical gear system is obtained caused by tooth surface wear. Thus, the vibration response characteristics caused by wear faults are obtained, providing a theoretical basis for the diagnosis of gear wear fault in the vibrating screen exciter.

In addressing the challenges posed by the high cost and substantial sludge volume of conventional lime neutralization methods for acid mine water (AMD) with elevated iron content, a synergistic biological-chemical resource treatment process based on immobilized Thiobacillus ferrooxidans has been developed. The application of carrier immobilization technology results in enhanced biological oxidation efficiency, with the Fe2+ oxidation rate reaching 250mg/(L·h) and an oxidation efficiency of 99% under conditions of 30°C, a gas-to-water ratio of 150:1, and a hydraulic retention time of 3.5 hours. This results in stable and highly efficient oxidation of the influent Fe2+ concentration of 797 mg/L. The step-by-step precipitation method is then adopted for the selective recovery of iron resources, with the pH level of 3.5-4.0 being regulated by NaOH. The precipitation product is analyzed by XRF, which shows that the quality of Fe2O3 accounts for 93% of the total. The residual pollutants meet the standard after secondary neutralization and precipitation. The integration of biological oxidation and step-by-step precipitation technology within this process establishes a closed-loop system for pollution control and resource recovery, thereby providing a sustainable solution for the efficient recovery and eco-friendly management of iron resources in high iron-containing AMD.

Direct coal liquefaction pitch is a solid product of direct coal liquefaction with hydrogenation, accounting for about 30% of the raw coal. It has the characteristics of high aromaticity, high carbon content, and easy polymerization or cross-linking, which makes it an excellent precursor for preparing high value-added carbon materials with a wider range of application scenarios and high economic value. This article introduces the source, chemical composition, and macromolecular structure of direct coal liquefaction pitch, compares the differences between direct coal liquefaction pitch and coal tar pitch, and introduces the purification and modification methods of direct coal liquefaction pitch. Besides, this review specifically emphasizes the research progress of direct coal liquefaction pitch in the field of generalized carbon materials, including modified pitch, carbon fiber, needle coke, porous carbon materials, energy storage materials, etc. Finally, the key indicators and limiting factors in application are further revealed, and the prospects for the application of direct coal liquefaction pitch are discussed.

To enhance flotation efficiency of scarce coking coal slimes, this study investigated n-hexane and cyclohexane as flotation reagents, systematically examining how aliphatic chain versus cyclic molecular structures influence coal slime beneficiation performance using 1/3 coking coal from Xinwen Coal Preparation Plant. Integrated methodologies including flotation tests, contact angle measurements, density functional theory (DFT) computations, and molecular dynamics (MD) simulations elucidated structure-performance relationships at macroscopic and microscopic scales. Results demonstrate n-hexane's superior flotation efficacy compared to cyclohexane: at 2000 g/t collector dosage, n-hexane achieved 68.93% combustible recovery versus 64.79% for cyclohexane. Contact angle analysis revealed coal particles treated with n-hexane exhibited 178° hydrophobicity, significantly higher than the 152° observed with cyclohexane. DFT calculations indicated n-hexane's higher molecular polarity index (MPI is 2.85 kcal/mol) versus cyclohexane (2.45 kcal/mol), signifying stronger adsorption affinity on coal surfaces. MD simulations further confirmed n-hexane's enhanced spreading behavior and reduced molecular mobility on coal interfaces relative to cyclohexane. This work establishes that the collector with long chain structure is more advantageous in the process of coal slurry flotation, which provides a theoretical basis for the molecular design of high-performance coal slurry flotation capture agent.

Ash content detection of coal slime flotation tailings is a crucial aspect of flotation process intelligence. To enhance the accuracy and stability of ash content detection in flotation tailings and address the susceptibility to failure of ash prediction methods based solely on surface slurry images in complex coal preparation plants, this paper presents the design of a novel image acquisition device inspired by the hand movements of on-site operators. The core of this device is an anthropomorphic motion module driven by dual motors. Its design adheres to the fourth strength theory of material mechanics and employs maximum deflection as the criterion for verifying structural strength and rigidity. Motion optimization is achieved using quintic polynomial S-curve velocity planning to ensure mechanical integrity, operational smoothness, and impact reduction. The device integrates an image acquisition module comprising a CCD camera and a ball screw feed system to capture images of both the slurry surface and settled solids. It also incorporates a conveying pipeline, an oil film removal module, and a sample retention bucket. The oil film removal module exploits the density difference between slurry and oil film for preliminary separation, followed by residual oil film removal via airflow. An experimental platform was constructed for validation. Results demonstrate that the device can stably acquire images of tailings slurry surfaces and sediments, featuring a rational structural design and performance achieving parity with manual operation levels.

With the increasing depth of coal resource exploitation in China, the limitations of traditional shaft construction methods in terms of efficiency and safety have become increasingly evident. This study focuses on Shaft Boring Roadheader. Based on the finite element dynamic simulation method, the effects of cutting drum rotation speed, traction speed, and milling depth on cutting load, power, and specific energy consumption were systematically analyzed. Additionally, the rock-breaking characteristics of pick cutters and shell cutters in hard rock with boulder formations were compared. The results indicate that the horizontal and vertical cutting loads decrease with higher rotation speed, while cutting power and specific energy consumption increase significantly. Increasing traction speed leads to linear growth in load and power, but specific energy consumption peaks at a traction speed of 23 mm/s. Deeper milling reduces specific energy consumption but requires balancing the impact of load fluctuations on equipment lifespan. Therefore, appropriately reducing rotation speed, lowering traction speed, and increasing milling depth can significantly optimize specific energy consumption. In hard rock with boulder formations, shell cutters effectively isolate boulders and reduce load impact, while conventional picks are more efficient in pure hard rock. The findings provide theoretical support for the design of efficient deep shaft excavation equipment and the optimization of construction parameters.

The "borehole in place of roadway" technology has been gradually adopted in coal mine abandoned area gas extraction construction due to its ability to effectively increase the connectivity of fractures in the formation, enlarge the area of gas outflow channels, and improve gas extraction efficiency. According to the requirement of directional drilling of large diameter near horizontal high drilling hole, the helical tooth arrangement principle is adopted to optimize the circumferential layout of the blade. Improve the adaptability of drill bit to near horizontal drilling; Optimize the bit profile to ensure the bit steering performance; Adjust the waterway structure to ensure the drill washing effect; And through the optimization of surface additive technology, the automatic additive process is developed to harden the surface of the drill bit. The newly developed drill bit has been used in the field test of high level drilling in a coal mine in Huainan. The results show that when drilling into the sandstone and silt stone strata in the roof of coal seam, the average life of the two bits reaches 1898.5m. During drilling, the bit can drill along the preset trajectory, the drilling pressure is stable, the drilling pressure is stable, the drilling pressure is stable, the drilling pressure is smooth, and the water hole is not blocked after lifting the drill, which verifies that the tooth layout and water channel design are reasonable. The surface of the bit body has almost no wear, no cracks and no falling off, indicating that the bit additive technology is reasonable, the combination strength of the additive layer and the bit body is good, and the material hardness is high, which meets the requirements of large-diameter directional drilling with hole substitution, and provides a new solution for the design and manufacture of large-diameter directional drilling bits.