To address the contradiction between idle resources in closed coal mines in China and the shortage of empirical research facilities for mine safety, this study proposes an overall concept of constructing an engineering-scale in-situ test site by repurposing closed coal mines. Using Qinneng No. 3 Mine as the engineering background, and based on the “origin–in situ–in-field”concept, a roadway suitability evaluation system was established, comprising five primary indicators including safety controllability and module compatibility. The AHP–entropy weight method was employed to quantitatively optimize and select underground spaces. On this basis, seven categories of in-situ testing platforms—covering mine fire and ventilation, gas, rockburst, roof strata, water hazards, intelligent robots, and rescue drilling rigs—together with a ground-based integrated experimental control center were planned and designed. The total designed roadway length is 6,958 m, of which 6,183 m reutilizes existing roadways, achieving a roadway reuse rate of 88%. The results indicate that the proposed design can overcome the “scale effect” inherent in traditional laboratory research and can effectively enable the low-cost, large-scale construction of realistic disaster-simulation environments, providing a new pathway for the transformational utilization of closed coal mines.

Based on a comprehensive analysis of the current situation of resource occurrence and system status in the Shajihai coal mine integration area, it is proposed to use the existing industrial site and ground facilities. Through technical and economic comparison, the advantages and disadvantages of two development plans are compared from multiple perspectives. The development plan of building a new gentle slope auxiliary inclined shaft, using the original main inclined shaft, pedestrian inclined shaft, and return air vertical shaft, and transforming the original auxiliary inclined shaft into a concealed return air inclined shaft is determined. This plan can achieve the rationalization and maximization of resource development in the integration area, promote the scientific and balanced development of the mine, and comprehensively consider the production needs of the mine in the middle and later stages, laying the foundation for safe and efficient production of the coal mine.

To address the engineering challenges such as the efficient lowering of large-scale equipment and the coordinated operation of dual systems in the auxiliary vertical shaft of ultra-large mines, and to improve mine production efficiency, this study takes the Shitoumei No.2 Mine with a designed production capacity of 8.00 Mt/a as the research object to carry out the design of hoisting container layout schemes and research on key technological innovations for the auxiliary vertical shaft. In combination with the mine's hoisting task requirements, three layout schemes were proposed, namely the combination of wide and narrow cages with a shaft diameter of 10.0 m, the configuration of wide and narrow cages with a shaft diameter of 10.6 m, and the combination of wide cage and transport cage. A systematic comparative analysis was conducted from three dimensions: technical performance, economy and system reliability. The results show that the scheme of wide and narrow cage configuration with a shaft diameter of 10.6 m (Scheme 2) features sufficient hoisting capacity and safer and simpler equipment loading and unloading operations. Although its one-time construction investment is slightly higher, it has high system redundancy and strong risk resistance with prominent comprehensive advantages, thus being identified as the optimal scheme. To ensure the implementation of the optimal scheme, key technologies such as the customized structural design of a special double-deck wide cage and the optimization of integral lowering technology for large hydraulic supports were developed. Through measures including precise dimension optimization, high-strength and lightweight structural design, and the matching optimization of lowering process and system capacity, the safe and efficient integral lowering of 48 t hydraulic supports was realized, which solved the core technical problems in the hoisting of the auxiliary vertical shaft of ultra-large mines. The research results provide a reliable reference for the hoisting design of auxiliary vertical shafts in ultra-large mines under the same conditions and have a demonstrative significance for promoting the technological progress of coal mine vertical shaft hoisting.

To meet the continuous mining demands of open-pit coal mines, this paper systematically studies the design theory and synchronous control technology of sandwich belt conveyors. Through theoretical derivation and experimental validation, conveying capacity and pressing force models are established, revealing that syn-chronous operation of the dual belts reduces pressing force by approximately 50%. A stress-superposition-based method for calculating concave/convex arc radii and a simplified design approach for multi-layer belts are proposed. A dual-belt synchronous control system based on PID and cross-coupling compensation is developed, integrating a speed-tension cooperative protection mechanism to achieve high-precision dynamic matching and anti-slip protection. Verification using a prototype with a 1200 mm belt width and a 60° inclination demonstrates the accuracy of the theoretical models and the effectiveness of the synchronous control. The research provides key technical support for the domestic application of sandwich belt conveyors.

The liberation and re?separation of coking middlings is an important approach to promote the clean and efficient development and utilization of coal resources. Taking the middlings from a coal preparation plant in Shanxi as the test object, comparative tests of three crushing and liberation methods (impact, compression and shear), comparative grinding tests (full?size grinding vs. classified grinding), and flotation tests were systematically carried out to investigate the effects of crushing mode, grinding method and flotation flowsheet on the separation performance of the middlings. The results show that compression crushing can achieve selective liberation of the middlings. By adopting classified grinding combined with a one?stage roughing and one?stage cleaning flotation process, a clean coal product with a yield of 21.95% and an ash content of 12.70% can be obtained (the ash content can be reduced to below 12.50% after parameter opti-mization). Finally, a combined quality?improving process consisting of compression crushing, classification at 0.5 mm, classified grinding, and one?roughing one?cleaning flotation is established, which can provide a technical reference for the resource recovery of similar high?ash coking middlings.

Rapid excavation is an important technical path to solve the problem of imbalanced coal mining. Huangbaici Coal Mine has constructed a rapid excavation system with self moving row support and hydraulic anchor drilling truck as the core. However, there are frequent biting accidents during the support moving process and limited construction space of the hydraulic anchor drilling truck, resulting in low excavation efficiency. Therefore, this article analyzes the key factors that restrict the improvement of tunnel excavation speed and proposes targeted optimization techniques. The results show that the self moving row support is designed as a frame type grouping and control structure, which can easily cause asynchronous movement of the two sides of the support, leading to biting accidents after the vertical beams of the support come into contact and collide; The operating range of the rear bridge type transfer machine encroaches on the construction space of the hydraulic anchor drilling truck, making it impossible to achieve mechanized anchoring operations, resulting in excavation and support still being sequential operations, and the start-up rate of the comprehensive excavation machine is only 45% to 50%. Based on this, the synchronized movement and anti biting frame sound light linkage optimization technology of the row support and the multi-dimensional excavation and support construction process optimization technology in space were proposed, realizing the parallel operation of front excavation and rear support and excavation and support, and increasing the tunnel excavation speed from 220m/month to 350m/month. The research results can provide reference for rapid excavation construction of tunnels under similar conditions.

Taking 20601 haulage roadway of Dahaize Coal Mine as the engineering background, this paper studies the roof subsidence control and the determination of reasonable empty roof distance in the process of roadway excavation. By constructing the mechanical model of heading roof, the calculation formulas of roof deflection in disturbed area, empty roof area and unstable support area are derived, and the effects of empty roof length, direct roof load, support strength and direct roof elastic modulus on roof subsidence are analyzed. A numerical model is established to reveal the stress distribution, plastic zone law and deformation law of surrounding rock under different length of empty roof and support strength. According to the theoretical analysis and numerical simulation results, the original support scheme was optimized, the length of the empty roof area was increased from 2 m to 3 m and the support strength was improved. The engineering application results show that the optimized scheme not only ensures the stability of the roadway, but also improves the excavation and support efficiency. The bolt support density is reduced by 35.7%, and the tunneling speed is increased from 481.8 m/month to 640.5 m/month. The research results can provide theoretical basis and practical reference for similar projects.

In response to the frequent occurrence of rock burst in the hard roof working face under high stress conditions in the deep mining area of Ordos, a case of rock burst in the deep high-stress mine of Hulusu Coal Mine in Inner Mongolia was selected. The mechanism of rock burst induced by the hard roof under the conditions of deep mining and high stress in Hulusu Coal Mine was analyzed. In order to explore new methods for dealing with the hard roof, the abrasive jet axial cutting technology for the hard roof was introduced. Industrial tests were carried out to determine the key technical parameters of abrasive jet axial cutting and fracturing, and engineering practices for preventing rock burst under the conditions of hard roof were carried out. The implementation process and the effect during the mining process were inspected by using borehole inspection and microseismic monitoring methods. The research results show that the high stress in the wide coal pillar, the large amount of elastic energy accumulated in the lateral suspended roof, the advanced support pressure of the mining face, and the abnormal stress in the mining space area are the main factors inducing rock burst. The process parameters of abrasive jet axial cutting were determined through the test: cutting pressure of 45-50 MPa, cutting time of no less than 10 minutes, fracturing pressure of 35-40 MPa, and fracturing time of 30 minutes. Compared with blasting pressure relief, after the abrasive jet axial cutting of the hard roof, the activity of the surrounding rock in the mining face during the mining period is reduced, the release of elastic energy is stable, and the large deformation of the surrounding rock in the adjacent tunneling face is mitigated, which is beneficial to the maintenance of the tunneling face during the tunneling period.

To reveal the macro-micromechanical properties and phase transition-like failure mechanisms of weakly cemented sandstone in the Tiaohu Mining Area, Xinjiang, and to address the challenge of controlling roadway surrounding rock in this special stratum, a systematic experimental study was conducted on the microstructure and mechanical properties of Jurassic weakly cemented sandstone from the Tiaohu No.1 Mine. Nuclear Magnetic Resonance (NMR) technology was used to characterize the micro-pore structure features of weakly cemented sandstone from both the superficial soil segment and the bedrock segment. Triaxial cyclic loading-unloading tests under different confining pressures were performed using an MTS816 rock mechanics testing system to analyze the deformation laws, strength evolution characteristics, and phase transition-like instability mechanisms of sandstones with varying degrees of cementation. Considering the complex geological conditions of the mining area, characterized by fault cutting and fold development, a support philosophy centered on "active control" was proposed. A zoned, graded, and differentiated active support system was established, and its effectiveness was verified through FLAC3D numerical simulation. The results indicate that: the proportion of transition pores and fractures in the bedrock segment sandstone is higher than in the superficial soil segment, leading to stronger water conductivity, while the superficial soil segment sandstone contains a higher content of weakly cemented components, resulting in more significant slaking characteristics upon contact with water; the uniaxial compressive strength of the typical weakly cemented sandstone in the mining area is 1.5 to 2 times lower than that of similar sandstones in central and eastern China, exhibiting significant post-peak brittle failure characteristics with an almost complete loss of strength, indicating typical phase transition-like instability behavior; the sensitivity of damage evolution in weakly cemented sandstone to confining pressure increases with higher cementation degree, and a lower cementation degree leads to more pronounced phase transition-like failure characteristics; the optimized high pre-stress active support system can effectively inhibit the development of the plastic zone in the surrounding rock and improve its stress state. The research findings can provide theoretical basis and engineering reference for the support design of roadways in weakly cemented strata in the Tiaohu Mining Area and similar mines in western China.

To ensure the secondary reuse effect of small coal pillar-gob-side entry retaining, taking the bilateral gob-side entry retaining of 150207 transport crossheading of Yangchan Coal Industry as the engineering background, the theoretical analysis and numerical simulation methods are used to study the fracture characteristics of overburden rock structure after primary mining and secondary mining of roadway roof. The mechanical model of bilateral gob-side entry retaining roadway is established, and the core influencing factors of large deformation of surrounding rock of gob-side entry retaining are obtained. The roof cutting and pressure relief technology of bilateral gob-side entry retaining roadway is proposed, and the key parameters of roof cutting and pressure relief are determined. The field application results show that the technology can effectively suppress the convergence deformation of the surrounding rock of the retaining roadway and meet the return air demand of 150209 working face. The research in this paper has certain reference value for the gob-side entry retaining project under similar conditions.

In order to study the development pattern of water-conducting fracture zones in hard roof strata, the 1312 working face of No. 15 coal seam in Yixin Coal Mine was selected as the research object. Various methods such as empirical calculation, key layer theory, FLAC3D numerical simulation, borehole viewing imaging, and segmented water injection were adopted to compare and analyze the development pattern of water-conducting fractures in hard roof strata. The research results show that the heights of the water-conducting fracture zone measured by the drilling observation method and the segmented water injection method are basically the same, and they can mutually verify each other. Both of these measurement methods are reliable. The height of the water-conducting fracture zone simulated by FLAC3D numerical simulation is relatively close to the measured height, and the credibility is relatively high. The calculated height of the water-conducting fracture zone using the empirical formula is significantly lower than the measured height, and the reliability is not high. Calculating the height of the water-conducting fracture zone directly using the empirical formula may lead to safety accidents. The height of the water-conducting fracture zone gradually increases as the coal seam is mined forward. When the mining length is approximately equal to the width of the working face, the height of the water-conducting fracture zone reaches its maximum and remains constant thereafter. Moreover, the water-conducting fracture zone is distributed in a saddle-shaped manner along the vertical direction. The height of the water-conducting fracture zone in the 1312 working face is 53.09 m, and the fracture-production ratio is 19.67. The research results provide certain basis and reference for the study of the height of the water-conducting fracture zone in the hard roof of the Qinshui mining area and its surrounding areas.

To address the pose variations of target coal gangue caused by belt slippage, deviation, and speed fluctuations during coal gangue sorting operations, which make traditional belt-speed–based tracking methods incapable of accurately perceiving target poses in real time and may result in missed, failed, or empty grasps, this paper proposes a dynamic coal gangue tracking method based on an adaptive multi-feature ECO-FCC algorithm. An adaptive feature fusion strategy is employed to integrate CNN, fHOG, and CN features extracted from coal gangue tracking images, thereby improving target localization accuracy. An adaptive scale estimation strategy is introduced to dynamically adjust the tracking bounding box and obtain optimal target scale estimation. In addition, an occlusion-aware model updating mechanism is designed to enhance the robustness of the proposed method under complex operating conditions. Based on a self-developed dual-arm gantry-type coal gangue sorting robot platform, comparative tracking experiments are conducted under different belt speeds, different target scales, and different camera–robot installation configurations, in which the proposed method is compared with KCF, CN, fDSST, SiamFC, C-COT, ECO, and ECO-HC. Experimental results demonstrate that the proposed method achieves an accuracy of 97.4%, a success rate of 90.9%, and an average frame rate of 52.4 FPS, exhibiting high tracking precision, strong robustness, and good real-time performance, and effectively meeting the requirements for accurate dynamic tracking of coal gangue.

In order to analyze the mining response of steeply dipping and extra-thick coal seam, the stress evolution characteristics of coal rock in steeply dipping and extra-thick coal seams were studied through theoretical analysis, numerical simulation and similar simulation. The stress deflection damage law of coal and rock was obtained, and the zoning fracture behavior of the overburden in steeply dipping and extra-thick coal seams was clarified. The results show that the upper coal rock is characterized by arched stress zone, and the maximum principal stress peak of top coal and overburden is relatively advanced. The principal stress 1 along the Y-axis component of the coal and rock in steeply dipping and extra-thick coal seam is relatively small near the working face, and the stress and the Z-axis angle are characterized by a gradual decrease along the strike. The minimum principal stress 3 deflects significantly along the Y-axis, and its X-axis component exhibits an increasing-then-decreasing trend along its strike. As the angle between principal stress 1 and the long axis of fracture increases, the stress inside coal rock increases first and then decreases. The mining response is most intense in the upper roof of the steeply dipping and extra-thick coal seam, with mining stress showing a surge trend. The mining response in the middle roof is relatively stable, the mining stress in the lower strata is the weakest. The above research provides a theoretical basis for the analysis of mining effect of steeply dipping and extra-thick coal seam, and has certain reference value for the stability control of surrounding rock of steeply dipping and extra-thick coal seam.

Extremely thick sandstone roof slabs frequently occur in mines at depths exceeding one thousand metres. Investigating the fracture, rotational movement, and energy release of these overlying sandstone slabs in large-scale goaf areas with multiple working faces forms the foundation for preventing and controlling rock bursts. Using the second block area of Zhengtong Coal Industry as the engineering context, this paper examines the mechanism of rock bursts in extremely thick sandstone roofs through a combination of theoretical analysis and similar simulations. Research indicates that the initial breaking energy of the extremely thick sandstone roof exceeds the periodic breaking energy. This breaking energy correlates positively with the thickness of the rock layer and the tensile strength, while it correlates negatively with the width of the working face and the overburden load. The disparity between the initial breaking energy and the periodic breaking energy is directly proportional to the width of the working face. Throughout the mining process, the stress within the coal seam increases incrementally as sub-critical layer 1, sub-critical layer 2, and the main critical layer fracture. The main critical layer undergoes three stages during mining: an increase in suspension distance, bending and subsidence, followed by the development of fractures. This research achievement establishes a theoretical foundation for investigating the mechanisms of rock bursts under analogous engineering conditions.

Aiming at the problem that most of the explosion energy of deep hole blasting in complex stress environment shrinks in the crushing zone and cannot be effectively used in the crack propagation of coal seam, the influence of control hole diameter on the antireflection effect of blasting is studied. Based on the mechanism of control hole under blasting load, three groups of comparative tests were carried out by using the self-built similar simulation test platform without control hole, ordinary control hole and reaming. The crack propagation characteristics, stress wave propagation and coal damage evolution law in the blasting process were obtained. The results show that the existence of the control hole can guide the blasting crack to expand along the direction of the connection between the blasting hole and the control hole, forming a penetrating main crack. At the 2# measuring point, the peak tensile strain of the reaming test block and the control hole test block increased by 36.4% and 16% respectively compared with the non-control hole test block, indicating that the increase of the control hole diameter can significantly enhance the stress concentration effect around the control hole, increase the tensile stress amplitude, and promote the formation of the cross-fracture network between the two holes. The ultrasonic inversion results show that the wave velocity reduction of each model on the S2 detection surface after blasting is 30.46%, 36.92% and 42.78%, respectively. The damage of the reaming test block between the two holes is more significant, indicating that the large-aperture control hole can more effectively improve the explosion energy utilization rate and anti-reflection range. The research results can provide experimental basis for parameter optimization of controlled blasting in high gas coal seam.

China began to study and apply the bolt (cable) support in 1956, and the cable support has become the main support means of tunnel and underground. At present, the anchor cable anchorage is mainly end anchorage, and the unanchored part is easy to be affected by rock pressure disturbance, rock energy accumulation and fatigue damage, which will affect the strength of the anchor cable. Aiming at the problem of whether the cyclic dynamic load of the anchor cable affected the strength performance of the anchor cable, this paper uses the method of theoretical analysis, numerical simulation and laboratory experiment to analyze the performance and fatigue damage characteristics of the anchor cable under different cyclic loads.The research results show that the tensile limit displacement of the anchor cable is approximately 13mm. Exceeding this value will cause irreversible damage to the structure. When the cyclic load reaches 85% of its ultimate bearing capacity and the tensile rate reaches 9%, the anchor cable enters the critical state of fatigue damage. Under a cyclic load of 450kN, the tensile breaking peak of the anchor cable is increased by approximately 11% compared to the 400kN condition, demonstrating a certain load strengthening effect. The research results on the damage caused by the cyclic loading of anchor cables have certain theoretical and engineering application value for the support of shafts and tunnels.

Hard inclusions such as fluid inclusions are commonly hosted in coal seams during coal mining operations, and the hardness of such inclusions is significantly higher than that of the coal matrix. When a shearer drum cuts a coal seam containing inclusions, problems such as a sharp increase in the instantaneous impact load on the cutting system and abnormal wear of pick cutters are prone to occur, which seriously impairs the operating efficiency of the shearer. It is thus imperative to conduct a systematic study on the influence laws of key factors (including inclusion size, spatial distribution position and structural parameters of the shearer drum) on the dynamic cutting characteristics, cutting resistance characteristics and pick force-bearing characteristics of the drum. In this paper, a research method combining theoretical analysis and numerical simulation was adopted to systematically investigate the influence laws of inclusion size parameters, spatial position parameters and the included angle between adjacent picks on the number of participating cutting picks during the process of cutting inclusions. Taking the number of picks involved in cutting inclusions as a key intermediate variable, the internal correlation mechanism between the size characteristics of inclusions and the cutting characteristics of the shearer drum was deeply analyzed. The research findings show that the size of inclusions along the traveling direction of the drum has a significant effect on the number of picks cutting simultaneously. Especially in the middle of the coal seam, even small inclusions can cause more picks to work at the same time, leading to a load rise. Increasing the included angle between adjacent picks (e.g., from 15° to 25°) will increase the minimum size requirement of inclusions in the vertical direction by about 15%, thereby reducing the number of picks in simultaneous contact and helping to lower the overall load. The research content and conclusions of this paper can provide ideas and a theoretical basis for the structural design of shearer drums for cutting inclusion-rich coal seams.

To meet the requirements of high efficiency, safety, and green development in the coal industry, the application status, core constraint, and future development trends of laser technology in fully mechanized coal mining equipment were summarized. Laser technology has achieved excellent improvement effects in fields such as the positioning, navigation and condition detection of fully mechanized mining equipment. In terms of positioning and navigation, the fusion technology of lidar and inertial navigation has solved the positioning problem in underground environments, enhancing the positioning accuracy of coal mining machines and the support accuracy of hydraulic supports, and improving the daily advancement speed of the working face and the precision of equipment coordination. In terms of condition monitoring, technologies such as laser ultrasound and profile scanning have achieved non-contact monitoring of the core components of fully mechanized mining equipment. The lead time for fault early warning has been further extended, unplanned shutdowns of scraper conveyors have been significantly reduced, and efficiency losses caused by pick wear of shearers have been notably lowered. The large-scale application of laser technology still faces three key constraints: the high-humidity, high-dust, and strong-vibration underground environment leads to energy attenuation of laser equipment and increased positioning errors; the initial cost of laser systems is relatively high, resulting in a long investment payback period for small and medium-sized coal mines; there are technical shortcomings in the real-time processing of laser data from a single working face and the collaboration of multi-system data. In the future, through the integrated hardware innovation of moisture-proof, dust-proof, and shock-absorbing functions, the multi-technology integration, the replacement of domestic core components, and the establishment of industry detection standards, laser technology will become the core driving force for promoting the intelligent upgrading of fully mechanized coal mining.

Hidden hazardous factors constitute the core bottleneck constraining safe and efficient coal mining operations. Their dynamic identification, transparent representation, and process management represent the key tasks in current surveys of concealed hazards. Taking Ningxia's Wangwa No. 2 Mine as the study area, a transparent management system for concealed hazard factors based on intelligent geological assurance technology was established. By integrating geological exploration data, mining engineering information, and multi-source hazard monitoring data, multi-attribute geological models for water hazards, gas, and rock pressure were developed. Spatial interpretation and dynamic updating of concealed hazard structures were conducted. Building upon this foundation, key technologies including dynamic risk assessment, hazard prediction and forecasting, and spatial analysis were integrated to develop a transparent geological assurance system covering water hazard management, rockburst prevention, and gas hazard control. Functional modules such as intelligent identification of geological anomalies and dynamic assessment of hazard risks were established. Results demonstrate that by embedding concealed hazard factor information within the transparent geological model, the system significantly enhances the visualization, traceability, and early warning capabilities of hazard factors. It provides effective support for the comprehensive survey of concealed hazard factors and safety decision-making at Wangwa No. 2 Mine.

Based on the data of coal and gas outburst accidents in China from 2015 to 2024, the instantaneous/delayed types, omens, delay time, operation types and casualties of 52 outburst accidents were analyzed systematically by statistical analysis method. Among them, 36 cases were delayed type causing 198 people death. The frequency and harmfulness of delayed outbursts (69.2%) were significantly higher than that of instantaneous outbursts (30.8%) in which 79 people died; 47.2% of delayed outbursts had obvious signs (such as drilling anomaly and gas emission anomaly), and 77.4% of the delayed outbursts have delay time within 24 hours. Different operation types have significant influence on outburst occurrence, instantaneous outbursts were induced by fully mechanized tunneling accounting for 50%, while delayed outburst mostly occurred in cleaning coal and rock (33.3%) and borehole drilling (27.8%); the average death number of each outburst accident occurred in the process of support operation is the highest, reaching 9.5. The above results show that delayed outburst has become the main type of coal and gas outburst in China in recent ten years, and its harmfulness is greater, and most of them are accompanied by obvious omens; different operation types have significant effects on the occurrence mode and consequences of outburst, so differential prevention and control measures should be taken according to different operation types.

To systematically integrate the key technologies of intelligent open-pit mines and improve the level of green and efficient production in mines, this paper proposes a method for constructing a technology system that integrates CiteSpace knowledge graph and expert investigation method. Based on 1182 documents and multi-source data, the study adopts the DA-BERT-BiLSTM-CRF model to extract technical entities, constructs a domain knowledge graph through entity alignment and knowledge fusion, and establishes the corresponding technology system by combining expert questionnaires. The results show that the F1-score of the DA-BERT-BiLSTM-CRF model for technical entity extraction reaches 0.912; the constructed domain knowledge graph covers four types of entities, namely technology, environment, process, and equipment; the established intelligent open-pit mine technology system covers four major links: drilling and blasting, loading, transportation, and dumping, and clarifies the key technology integration path and its comprehensive optimization effect on production efficiency, cost control, and environmental governance. This technology system construction method can effectively integrate the key technologies of intelligent open-pit mines, provide strong technical support for the green and efficient production of mines, and the revealed key technology integration path can also provide important reference for the practice of mine production optimization.

To meet the demand for high-performance shotcrete in underground engineering, the effects of single and combined incorporation of nano-silica (NS) and nano-alumina (NA) on its workability, mechanical properties, and microstructure were investigated. Different mix proportions with varying dosages were designed, and slump as well as compressive strength at different curing ages (3, 7, and 28 days) were tested. Digital image correlation (DIC) technology, stress-strain curves, failure patterns, and scanning electron microscopy (SEM) were employed for analysis. The results indicate that single incorporation of 3% NS or 3% NA enhances strength, with 28-day compressive strength increasing by 15.9% and 11.1% respectively compared to the control group, though slump decreases. The combined incorporation system (total NS and NA dosage of 3%) demonstrates superior strengthening effects, with the optimal synergistic ratio of NS to NA at 2:1, achieving a 35.1% increase in 28-day compressive strength. DIC analysis indicates that the combined addition results in a more uniform distribution of cracks during specimen failure, a reduction in the width of primary cracks, a gentler descending segment in the stress-strain curve, and improved ductility. Microstructural analysis further confirms that NS and NA generate gel through pozzolanic reactions, exert micro-aggregate filling effects, and optimize the interfacial transition zone, leading to a denser microstructure. This study verifies that combined incorporation of NS and NA enhances the overall performance of shotcrete, providing an experimental basis for its engineering applications.

New Julong fat coal is a high-quality coking coal resource, but due to oxidation, the surface oxygen-containing functional groups increase significantly and the hydrophobicity decreases, resulting in deterioration of flotation dynamics and serious loss of refined coal. In this paper, the mineral composition and surface chemical properties of oxidized raw coal were analyzed by XRD, XRF, XPS, etc., and the oxidation characteristics of polar groups such as C-O/C=O were revealed, and the content of hydrophilic minerals such as kaolinite and quartz was high. The infrared spectroscopy after high shear slurry conditioning showed that the absorption peak of oxygen-containing functional groups was significantly weakened, and the high-shear slurry adjustment could effectively clean the oxide layer and fine mud cover on the surface of coal particles, and improve the dispersion and adsorption of the agent. The flotation kinetics analysis showed that the ultimate recovery rate ε∞ increased from 55.12% to 62.61%, and the k value increased from 1.52 to 1.57, which significantly improved the flotation kinetics of oxidized coal．

Against the backdrop of deep integration between new-generation information technology and enterprise management, the integration of business and finance has become a core driving force in promoting the digital and lean transformation of engineering project management. This paper addresses issues in traditional engineering project management, such as the disconnection between schedule management and financial control, data silos, and delayed decision-making. Taking the construction of Shenyang Design Institute’s digital management platform as a case study, it systematically elaborates on the practical approach to lean schedule management in engineering projects under the concept of business-finance integration. By establishing a real-time linked control system centered on specific projects and integrating multi-dimensional schedule indicators — including planned progress, visual progress, owner settlement progress, collection progress, revenue progress, management expense disbursement progress, and payment progress — and by leveraging automatic data synchronization, visual comparison of leading-edge lines, and intelligent early-warning rules, the system achieves collaborative visibility and dynamic adjustment of business flows and value flows throughout the project lifecycle. Practice shows that this model significantly enhances the accuracy of project schedule control, the timeliness of risk prediction, and the scientific nature of management decisions, providing a valuable reference for engineering enterprises in advancing digital transformation and refined management.

With the continuous increase in mining depth and scale, the energy-efficient operation of mining counter-rotating fans has become increasingly critical. While adjustable-blade counter-rotating fans can adequately meet the varying demands for air volume and pressure in fully mechanized mining faces, they face challenges such as limited underground transportation space, difficulties in installation and maintenance, and high energy consumption. To address the lightweight design requirements of mining counter-rotating fans, a three-dimensional solid model of the fan was established, and finite element analysis was performed on its key component—the hub—using Ansys Workbench. Based on the simulation results, an orthogonal experimental design was employed, selecting four parameters—hub width, hub plate thickness, concavity depth on both sides of the hub, and side plate thickness—as experimental factors. Range analysis was used to investigate the influence of these factors on the hub mass. Finally, structural optimization of the hub was carried out. The results indicate that side plate thickness and hub plate thickness have a significant impact on the overall hub mass. After optimization, the hub mass was reduced by 3.90 %, and the maximum equivalent stress decreased by 4.27 %. The optimized hub meets strength requirements while achieving lightweight objectives.

Mine shuttle cars have extensive applications in fields such as coal tunnel excavation, recovery of leftover coal, "three?down" coal filling and mining, and salt mine mining. With the continuous development of intelligent coal mines and unmanned vehicle technology, mine shuttle cars are gradually moving towards unmanned operation. However, the working environment of mining shuttle cars is complex, especially in the narrow coal mine roadways, where the shuttle cars are confronted with the challenges of trajectory planning and turning difficulties. In response to these problems, taking the unmanned shuttle car as the research object, through the analysis of its steering structure, simulation experiments were conducted to carry out the research on the trajectory planning of the mine shuttle car underground. Firstly, by analyzing the characteristics of the non-integrity constraints of the shuttle car, the kinematic equation was analyzed and derived, and the Hybrid A* algorithm and the TEB algorithm were determined as the basic algorithms for the trajectory planning of the mining shuttle car. Secondly, in view of the problems such as the large number of search nodes and the existence of paths with large curvature in the traditional Hybrid A* algorithm, the strategies of dynamically expanding the step size and dynamically using the RS curve are adopted. The calculation method of obstacle density is proposed and introduced into the steering penalty function. The reversing penalty is added to the cost function for the driving mode of the shuttle car. The generated paths were smoothed using the B-spline method. Global planning simulation experiments were conducted on the algorithms before and after improvement in the double-tunnel tunneling scenario. The results showed that the planning time of the improved D-Hybrid A* algorithm was reduced by 51.02%, the number of node expansions was reduced by 41.3%, and the number of turns was reduced by 36.36%. The efficiency was significantly improved. The generated path is smoother; Finally, aiming at the problems that the traditional TEB algorithm is prone to getting stuck in local optimum and generating trajectory oscillations, the obstacles were reconstructed, and an isolation layer was added outside the expansion layer to improve it. The simulation results of local trajectory planning of the algorithm before and after the improvement in the double-tunnel excavation environment were compared, indicating that the proposed S-TEB algorithm can achieve the functions of safe obstacle avoidance and stopping. Safe driving trajectories can be planned in various scenarios. The average efficiency of the improved S-TEB algorithm has increased by 22.89%, and the average safety performance has increased by 2.3 times compared to the original, which can meet the unmanned driving requirements of mining shuttle vehicles.