The "dual carbon" goals have driven explosive growth in the renewable energy industry, leading to surging demand for critical metals such as copper, nickel, and cobalt. As a strategic supplement to land-based resources, the development of deep-sea minerals has become a critical pathway to ensure supply chain security. Addressing China's high external dependency on critical metals and acute supply chain vulnerabilities, the strategic layout of the entire industry chain for deep-sea mineral resource development was systematically investigated. Building on the vast potential of international seabed resources such as polymetallic nodules, cobalt-rich crusts, polymetallic sulfides and deep-sea rare earths, and leveraging China's "first-mover advantage" of exclusive exploration rights and priority mining rights over five international seabed areas, competitiveness analysis indicates that China has advantages in exploration scale and manned submersible technologies. However, persistent bottlenecks are summarized, including reliance on imported core mining components and insufficient influence in international environmental standard-setting. A framework anchored in "top-level strategic planning, green technology innovation, industrial chain coordination, international rule leadership" was proposed. Key pathways encompass establishing a national collaborative mechanism to advance low-disturbance mining technologies, building a distributed industrial chain spanning "offshore mining-coastal preprocessing-inland refining", and spearheading international standards for sustainable deep-sea mining. Phase-specific milestones are defined: completing full-system sea trials in mining areas by 2030 and achieving an annual production capacity of 20 million tons of dry nodules by 2040. By integrating technological breakthroughs and international rule gaming, this framework provides strategic support for China to build an independent and controllable deep-sea resource supply system.

To ensure efficient resource collection while minimizing environmental impact, enhancing economic feasibility, and promoting the sustainable development of deep-sea hydraulic mining technology, a hybrid evaluation system was constructed for identifying key influencing factors and optimizing solution selection. Firstly, based on grounded theory, a comprehensive evaluation system was constructed from three dimensions of technology, environment and economy, which includes 5 primary indicators (environmental disturbance, collection efficiency, energy consumption characteristics, structural reliability and collection economy) and their corresponding 20 secondary indicators. Next, the Fuzzy-DEMATEL method and the CRITIC method were applied to determine subjective and objective weights, respectively, followed by comprehensive weighting. Finally, the Pythagorean fuzzy multi-attribute decision-making method based on PFHWD-TOPSIS was used to sort the alternatives and achieve scientific optimization. The results show that the constructed hybrid evaluation system can effectively support factor analysis and scheme decision-making, among which environmental disturbance and economic stability are the key constraint factors in the decision-making of deep-sea hydraulic mining schemes. In the four deep-sea hydraulic mining schemes, the wall-attached jet scheme (C₂) has the optimal comprehensive performance, and performs prominently in terms of environmental disturbance, energy consumption characteristics and economy. The research results can provide a theoretical reference for the optimization of deep-sea hydraulic mining schemes and help the sustainable development of the technology.

The hydraulic compensator in marine drilling equipment plays a critical role in regulating the pressure balance between internal and external environments and the machine's oil supply rate. Its working principle involves utilizing seawater pressure to compensate for volumetric changes in hydraulic oil caused by deep-sea pressure and ambient temperature differences, thereby preventing seawater backflow and subsequent equipment corrosion. A mechanical volume analysis on two compensators with different shapes was conducted using Ansys software, and their hydraulic circuits were simulated via AMEsim. Based on the original hydraulic circuit, additional components such as pressure reducing valves, check valves, and overflow valves were incorporated to construct a hydraulic circuit suitable for active operation mode. A comparative analysis of flow velocity before and after the improvements was performed. Furthermore, the influence of different structural parameters on the internal flow field under deep-sea working conditions was investigated. Finally, a new hydraulic compensator was designed accounting for the pressure and temperature conditions of the marine environment. The results demonstrate that the compensator with a multilayer folded structure and an inlet/outlet size of 20 mm delivers optimal performance. Its hydraulic system can supply a larger flow rate within a shorter time and exhibits enhanced adaptive adjustment capability for transient flow variations.

Deep underground metal mines are subjected to the long-term superimposed effects of high in-situ stress and cyclic blast-induced dynamic disturbance, making the surrounding rock prone to stress concentration, cumulative roof settlement, and intensified vibration response, which threaten stope stability and production safety. Existing mining parameter designs mostly rely on engineering experience and struggle to balance stope stability and production efficiency. To address this issue, a dynamic and static coupling optimization method for mining parameters was proposed to synergistically regulate factors such as stope span, pillar width, filling height, and explosive consumption. Dynamic response simulations based on a three-dimensional numerical model and field comparative verification were carried out. The results show that after the coordinated parameter optimization, the peak particle velocity (PPV) at a near-field distance of 10 m decreases from 31.3 cm/s to 14.5 cm/s, and the peak displacement of the bottom structure reduces from -0.64 cm to -0.18 cm. Within 24 hours after blasting, the mid-roof settlement droppes from 9.8 mm to 4.1 mm, and the height of the plastic zone extension in the roof decreases from 8.6 m to 5.1 m. These results demonstrate that the proposed parameter optimization method can effectively mitigate the effects of blast-induced disturbance, improve the stress state of the surrounding rock, and enhance stope structural stability, providing reliable optimization ideas and technical support for safe and efficient mining in deep mines.

The southeast ore body of the Chambishi Copper Mine is a typical deep-level mine in central and southern Africa. As the mining scope continuously expands, the underground ventilation system of the mine faces problems such as long ventilation routes, high ventilation resistance, uneven airflow distribution, and local ventilation difficulties, which severely affect mine production safety and the working environment. Taking the deep-horizon multi-shaft ventilation system of the mine as the research object, and based on systematic investigation and parameter determination, the ventilation districts were rationally partitioned. Furthermore, targeted optimization schemes were formulated from the perspectives of the ventilation network, ventilation engineering, ventilation structures, and ventilation power. In the south mining district, the 696 m level was utilized as the main return airway; coordinated with automatic ventilation doors and short shaft engineering, this configuration ensured the fresh air supply to the ramp. Furthermore, efficient ventilation at the 900 m level was achieved via the 800-680 m dedicated return shaft operating in conjunction with variable-frequency fans. In the north mining district, ventilation structures were added to seal the air leakage at the 980 m level, and a newly excavated intake shaft from the north main ramp to the 1 000 m level resolved the difficulty of fresh air intake in deep levels. A three-dimensional simulation model was established using Ventsim software, and the error between its simulation results and the measured data was less than 10%. After engineering application, the distributed air volume at the 900 m level increases to 102.2 m³/s, the air leakage volume of the south ore body decreases by 57.89%, and the effective airflow rate improves by 19.51%. The air volume in the deep middle level is obviously improved, and the underground environment is significantly improved.

Under the coupled action of high stress and aggressive media in deep mines, the support system is highly prone to structural failure due to stress-electrochemical coupled corrosion, which seriously threatens mine production safety. With the corrosion protection of bolts under a saline-alkali corrosive environment in a deep mine in Shandong taken as the engineering background, field investigation, laboratory tests, and numerical simulation were combined to investigate the variation law of the electrochemical corrosion rate of bolts after adding Cr₂O₃ corrosion inhibitor, and to comparatively analyze the corrosion evolution process of ordinary bolts and bolts with the corrosion inhibitor under the high-stress environment of deep mines. The results show that as the Cr₂O₃ concentration increases, the self-corrosion potential of the bolt rises from -1.062 V to -0.924 V, the corrosion current density decreases from 7.76×10^-5 A/cm² to 1.47×10^-5 A/cm², and the corrosion rate drops from 0.936 mm/a to 0.181 mm/a. The Cr₂O₃ corrosion inhibitor exhibits a significant inhibitory effect on electrochemical corrosion. The grouting body compressive strength test shows that with the increase of Cr₂O₃ concentration, both the 1 d and 7 d compressive strengths of the specimens present a trend of first increasing and then decreasing. The numerical simulation results show that after 1 500 d of corrosion, the ordinary bolt has large potential differences and concentrated current density, whereas the bolt with Cr₂O₃ has a uniform potential distribution. The total electrode corrosion thickness decreases from 68.7 μm to 0.182 μm, a reduction of 99.7%, and the surface concentrations of chloride, iron, and sodium ions on the anti-corrosion bolt are significantly lower than those on the ordinary bolt, indicating that the Cr₂O₃ corrosion inhibitor can achieve long-term inhibition of electrochemical corrosion under high-stress and high-corrosion environments.

To analyze the impact of external flow field pressure variations on the safety clearance during the operation of lifting container in ultra-deep metal mines, and to identify the key factors in the safety clearance design of mixed lifting container in ultra-deep shafts, a closed-loop analysis method integrating "multi-field coupled dynamics-regulatory codes-engineering design" was proposed. This method was utilized to investigate the key indicators of safety clearance for mixed lifting container in ultra-deep shafts under different operating conditions. Relying on the Daping Phosphate Mine mixed shaft project in Guizhou, a standard κ-ε two-equation turbulence model was adopted to perform a numerical simulation on the external flow field pressure variations of the lifting container during operation. The pressure distribution characteristics of the container during steady-state operation and the transient passing process were deeply investigated. Simultaneously, by comprehensively considering the key factors affecting the oscillation of the container, such as the torsional moment of the hoisting wire rope, the Coriolis force, and steady-state aerodynamic forces, the design safety clearance for lifting container in ultra-deep shafts was systematically analyzed and determined. The results indicate that the relative relationship between the operating direction of the container and the main airflow direction in the shaft is the key factor influencing the negative pressure in the passage. Under the counter-flow operating condition, the aerodynamic negative pressure effect is more intense, which makes it the critical operating condition for safety clearance design. Furthermore, the total lateral displacement of the lifting container is 158.8 mm, and the calculated safety clearance is 536.4 mm, which is higher than the safety clearance (528.9 mm) specified in the Safety Regulations for Metal and Nonmetal Mines. The research findings provide a scientific and reliable basis for the safety design of ultra-deep shafts, ensure the stable and safe operation of lifting systems in deep mining, and offer a theoretical reference for the evaluation criteria of safety margins in the safety clearance design of ultra-deep shafts.

To address the issues of a complex solution space, strong nonlinearity, and easy entrapment in local optima in microseismic localization, the application of swarm intelligence optimization algorithms in microseismic localization was systematically investigated. By comparing the performance of the sparrow search algorithm (SSA), differential evolution (DE) algorithm, and particle swarm optimization (PSO) algorithm in single P-wave localization, it was found that PSO algorithm exhibited the best performance in terms of solution stability. To further increase the localization accuracy and enhance algorithm robustness, S-waves were introduced to construct a dual-wave joint localization model, reducing the inversion space from four dimensions to three dimensions. The experimental results indicate that the dual-wave joint localization significantly outperformed the single P-wave localization, where PSO algorithm achieves the lowest average localization error in the dual-wave joint localization and demonstrated good adaptability. To overcome the shortcomings of the PSO algorithm, such as premature convergence and sensitivity to initial values, an adaptive improved particle swarm optimization (APSO) algorithm integrating opposition-based learning and chaotic mapping was proposed. Opposition-based learning was utilized to generate a high-quality initial population, while chaotic mapping achieved the dynamic adjustment of the inertia weight to balance the global exploration and local exploitation capabilities. The numerical experimental results indicate that the average localization error of APSO algorithm at multiple typical source points is lower than that of the standard PSO algorithm, with the average localization error reduced by approximately 62.4%, and it exhibits stronger stability and convergence efficiency. This method provides an effective tool for high-precision microseismic localization in deep rock mass engineering and has promising prospects for engineering application.

To achieve safe mining in the near-shaft area of steeply inclined thin orebody, a steeply inclined thin gold mine was taken as the engineering background. Combined with the geological conditions of the mine, the applicable mining method was preliminarily selected, and the primary selection scheme was optimized by using the analytic hierarchy process and fuzzy decision theory. FLAC3D numerical simulation was used to analyze the shaft stability during the mining process in the newly added recoverable near-shaft area. The results show that the upward drift filling mining method is the optimal mining scheme for the newly delineated area of the shaft safety pillar. Compared with ascending mining, descending mining reduces the extreme value of the maximum unbalanced force in the stope by 15%-20%, effectively alleviates the local stress concentration in the ore body, and helps restrain ground pressure activities and control shaft displacement. The optimized mining sequence gradually releases stress and creates a favorable stress environment for the stope. The filling body plays a key supporting role, and their synergistic effect significantly enhances the overall stability of the stope and effectively inhibits rock mass failure and propagation. The on-site monitoring results of the shaft indicate that after adopting the descending mining scheme, the maximum compressive deformation of the main shaft is 0.049 mm/m, and the maximum tensile deformation of the blind shaft is 0.151 mm/m, both values meet the requirements specified in safety regulations (2.0 mm/m). The field industrial test results show that the upward drift filling mining method has good safety and economic benefits, the resource recovery rate is increased to 95%, realizing the coordinated optimization of safety, economic benefit and resource recovery.

Based on the occurrence characteristics of the soft, fractured, and thick large orebodies in a gold mine, the mechanized upward drift filling mining method was recommended. Six sets of stope structural parameters were designed through an orthogonal experiment, and the FLAC3D numerical simulation software was utilized to analyse the stope stability. The simulation results indicate that the compressive and tensile stresses in the stope are mainly concentrated at the top and bottom corners of the sidewalls, and both exhibit a symmetrical distribution. The displacement values of the stope roof, floor, and hanging wall surrounding rock increase with the increase of the drift width and drift height, but the overall displacement values are relatively small. On the premise of ensuring the safety and stability of the stope, larger stope structural parameters are preferentially selected to improve the technical and economic indicators. Therefore, Scheme 3 (with both the drift width and drift height being 5 m) is determined as the optimal stope layout scheme. The field application results indicate that when the mechanized upward drift filling mining method is adopted for extraction, the stope production capacity reaches 220 t/d, and the development and cutting ratio is 24.5 m³/kt. Furthermore, the ore loss rate is 6.2%, and the dilution rate is 8.3%, achieving favourable technical and economic benefits.

In a gold mine, the uniaxial compressive strength of ultra-fine unclassified tailings backfill cannot satisfy the requirements of stope filling. To improve the backfill strength, steel fibers, polypropylene fibers and steel-polypropylene hybrid fibers were adopted as reinforcement materials for backfill, and the effects of fiber type, fiber dosage and curing age on the backfill strength were systematically analyzed. Based on the test data, a prediction model for backfill strength integrating Gaussian Process Regression (GPR) and Shapley Additive Explanations (SHAP) was proposed. The research results show that both steel fibers and polypropylene fibers can effectively enhance the backfill strength. Compared with the fiber-free blank control group, all fiber systems achieve the optimal strength enhancement at a fiber dosage of 0.3%. A typical nonlinear relationship of "promotion at low dosage and inhibition at high dosage" exists between fiber dosage and backfill strength. In addition, the established strength prediction model exhibits excellent prediction performance, and the average relative error of strength prediction is controlled within 10%. The SHAP analysis can accurately quantify the influence degree of fiber type, fiber dosage and curing age to backfill strength. The research results provide a quantitative basis for the mix proportion design of fiber-modified backfill and help promote the intelligent development of mine backfilling engineering.

To address the problems of weak research on solidification and slurry properties of classified overflow fine tailings and slow progress in underground backfill treatment of fine tailings, a small spread cylinder was used to measure the spread value to determine the paste backfill concentration. Using slag-based cementitious materials, solidification tests and slurry property studies were carried out on ultrafine tailings from middling overflow of an iron mine, classified overflow fine tailings from some gold mines, and unclassified tailings from several iron mines. The results show that the use of slag-based cementitious powder can effectively solve the problems related to the solidification and strength requirements of classified overflow ultrafine tailings. Ultrafine tailings have high porosity and low bulk density, and the slurry mass concentration can be as low as below 50%. Under the same binder dosage, the cement-tailing ratio of ultrafine tailings is relatively high, but the 28-day strength loss of the backfill is limited, and the increase in backfill cost is not significant. The slurry mass concentration has a significant effect on solidification strength. Under a filling line of 3.5 to 4.0, the ultrafine tailings backfill slurry can achieve gravity flow transportation without pumping.

To effectively solve the problems of severe backbreak damage, high oversize block ratio and poor stability of working face side when using large-diameter long-hole caving method in underground stopes, the optimization of axial charge structure was carried out based on the engineering background of three rows of large-diameter long-hole lateral blasting in underground stope of a copper mine in Anhui Province. LS-DYNA was used to establish five numerical models of axial segmented charge structures with three rows of blast holes. By analyzing the damage distribution law and failure volume of rock mass in different zones, the optimal charge structure for backbreak control in each row of blast holes were determined respectively. The numerical simulation results show that the axial charge structure can alter the distribution of explosion energy, thereby regulating the damage distribution and failure range of the rock mass. Considering both rock breaking effect and backbreak control effect comprehensively, it is recommended that the three rows of blastholes adopt axial charge structures with 1 m charge and 1 m air interval, 0.5 m charge and 1 m air interval, and 0.5 m charge and 1.5 m air interval, respectively. The field industrial test results show that after adopting the optimized charge structure, the number of oversize blocks in the collapsed muck pile decrease significantly, the reduction of sonic wave velocity in the rock mass of the imminent blasting zone is about 8.8%, and the rock damage value is basically less than 0.19. This indicates that the rock mass features favorable integrity and slight damage, and the backbreak control effect is remarkable.

To realize safe and efficient mining in a copper-nickel mine in Xinjiang, a horizontal lateral medium-deep hole blasting mining technology was proposed. Firstly, blasting parameters are preliminarily determined by the empirical analogy method: the blast hole diameter is 65 mm, the minimum resistance line is 1.625-2.275 m, the hole spacing is 1.300-2.275 m, continuous in-hole charging is adopted, the unit explosive consumption is 0.35-0.5 kg/t, and the millisecond delay initiation interval is 25 ms. Interval stemming is adopted for blast holes, with stemming lengths of 1 m and 2 m respectively. Subsequently, the LS-DYNA finite element software was used to carry out numerical simulation analysis on horizontal lateral medium-deep hole blasting. The numerical simulation results show that rock can be effectively broken by blasting and the stability of backfill roof can be guaranteed when the minimum resistance line is 1.5 m and the hole spacing is 1.0-1.5 m. Finally, field verification tests were carried out. The results show that the shape of the drift stope after blasting is relatively regular. The predicted overbreak and underbreak volume is less than 10%, No oversize blocks or fine ore are generated, and the backfill roof remains intact, achieving favorable blasting performance.

To accurately identify the key factors influencing the mining safety of underground metal mines and clarify the internal interaction logic among the influencing factors, an integrated analysis model for factors affecting mine mining safety based on Grey-DEMATEL-ISM-MICMAC was constructed. Through literature review and case analysis, 17 influencing factors were screened and identified from five dimensions: personnel, equipment, environment, management and technology. The Grey-DEMATEL method was employed to quantitatively analyze the importance of each factor. Combined with the ISM method, a multi-level hierarchical structure model was constructed to reveal the interrelationships among the factors. Finally, the MICMAC method was used to analyze the attribute characteristics of the factors. The research results indicate that the 17 influencing factors can be divided into 6 levels and 3 types. Employee training and education, safety production management system, safety hazard identification and rectification, and rationality of mining technology are the core influencing factors of mine mining safety, possessing characteristics of high driving force and low dependency. The reliability of safety protection devices, daily equipment renewal and maintenance, environmental hazard source control, working environment conditions, key technology application, and technological innovation are direct influencing factors, exhibiting high dependency characteristics. In response, combined with the actual engineering situation, targeted optimization measures are proposed, guided by the modernization and practicability of the management system, centered on the comprehensive improvement of personnel quality, based on the improvement of the working environment, and supported by the upgrading of technical equipment. The research results can provide theoretical basis and decision-making reference for enhancing the level of mine safety management.

To address the severe water inflow issue in the underground workings of the Mingniwan Phosphate Mine in Guizhou, after confirming substantial water loss from the surface river, water samples were collected from six underground water inflow points, the dolomite aquifer, and the Yangshui River for hydrochemical analysis. Six hydrochemical components, Ca²⁺, Mg²⁺, Na⁺+K⁺, , Cl^- and , were selected as discrimination indicators. The Piper trilinear diagram combined with Grey Relational Analysis (GRA) was applied to identify the sources of underground water inflow. The results show that the hydrochemical types of water samples from the Yangshui River, the 368 m grit chamber, the 490 m water sump, the 440 m goaf, the 524 m water sump, and the 520 m drift are all type, while those from the 650 m main slope surface and the dolomite aquifer are type. The water inflow source in the 440 m goaf is most likely from the Yangshui River, with the highest correlation degree of 0.94. The 650 m main slope surface shows the lowest correlation with the Yangshui River, but its correlation degree with the dolomite aquifer reaches 0.86, indicating a strong correlation, suggesting that the dolomite aquifer is a highly probable water inflow source. The Piper-GRA combined analysis method provides an effective technical solution for identifying water inflow sources and can serve as a scientific basis for subsequent formulation of water prevention and control measures.

The simulation method of drainage hole unit for finite element calculation of seepage field was summarized. On this basis, the direct simulation method of drainage unit for seepage well of tailings pond was proposed. This method establishes a solid mesh model containing optimization parameters of seepage wells all at once at the initial stage of calculation. Afterwards, the optimized elements of seepage wells were grouped in advance by setting different internal boundary conditions. During the finite element solution of the seepage field, the condensation of permeability conduction matrix only needs to be performed once. In the calculation process, the node information of each group was processed according to the first kind of known head boundary conditions. The whole process is easy to program and features fast solving speed. Compared with commonly used engineering methods such as the implicit composite element method and the improved drainage substructure method, the proposed method significantly improves the efficiency of modeling and solution through optimized parameter settings. Meanwhile, it greatly enhances computational accuracy by finely simulating the size effect of seepage wells. Finally, the calculation accuracy of the method is verified to meet the engineering requirements through a fully penetrating well example and a specific engineering case.

Aiming at the support problem of large deformation of surrounding rock in deep high ground stress roadway, a kind of compressible concrete-filled steel tube support structure (referred to as "compressible support") was proposed. Firstly, a comparison test of compressible similar materials was carried out, and PVC foam was determined to be applicable as the compressible similar material for simulation tests. Secondly, the similar simulation test of the compressible support was carried out, and the stress-time and load-displacement curves of the whole process of static load were obtained. The evolution of compressible support, initiation and propagation of concrete cracks was monitored. Three mechanical response stages of the compressible support were revealed: the elastic deformation stage, stable yielding stage and rigid stage after yielding. The test results show that the peak stress of the surrounding rock of the roof and floor is approximately 0.7 MPa, and the peak stress of the surrounding rock of the left and right sides is approximately 1.4 MPa. The stress of the surrounding rock is transferred to the depth, the supporting model does not experience overall instability and deformation, and the support is bent, but the structure is still intact. The compressibility of PVC foam measured is approximately 77%, indicating that the support achieves a favorable yielding effect. The field application results show that the maximum displacement of the roof and floor of the surrounding rock is 216 mm, and the compressibility of the compressible support is about 72%. The compressible support achieves favorable supporting performance, and the support structure can effectively coordinate the collaborative deformation of the surrounding rock and support. The research results can provide reference for the support design and engineering application of the compressible support.

To promote the resource utilization of industrial solid waste and the sustainable development of green wet-mix shotcrete, cement clinker-free solid-waste-based wet-mix shotcrete was prepared using steel slag, slag, and desulfurization gypsum as cementitious materials, and copper slag and waste rock as aggregates. Furthermore, raw material property analysis, mix proportion optimization, mechanical property testing, microscopic mechanism investigation, and on-site industrial tests were systematically conducted. The results indicate that the mechanical properties of the solid-waste-based wet-mix shotcrete with optimal mix proportions (specimens No.5 and No.9) are superior to those of the cement-based wet-mix shotcrete. The 7-day compressive strength of specimen No.9 reaches 16.31 MPa, and its 56-day compressive strength exceeds 28 MPa. Its workability is comparable to that of the cement-based wet-mix shotcrete, and the slump and slump flow meet the requirements of wet spraying operations. The solid-waste-based wet-mix shotcrete exhibits a remarkable solidification effect on heavy metals. It reduces the leaching concentrations of excessive heavy metals Pb and Cd in the copper slag to below the Class Ⅱ water quality standard for groundwater, demonstrating excellent environmental safety. Microscopic analysis results indicate that the solid-waste-based wet-mix shotcrete is rich in hydration products and exhibits a high degree of polymerization of the silicate gel. On-site tests verify the feasibility of engineering application for the copper slag wet-mix shotcrete. Although issues such as incomplete material discharge exist, they can be improved through process optimization. This provides an effective path for the harmless disposal and resource utilization of solid wastes such as copper slag, possessing environmental, economic, and social values.

Underground rock masses often contain fissures with different inclination angles and various fillings, and the crack propagation and failure behavior of rock bridge structures directly affect the stability of underground rock engineering. Through uniaxial compression tests on filled jointed red sandstone with different inclination angles, acoustic emission parameters (ring count, rise time, amplitude, duration) monitoring and FRACOD numerical simulation, the crack propagation law and damage mechanism of rock bridge structures in filled joints under different inclination angles of joint were systematically studied. The results show that the stress-strain curves exhibit three stages of compaction, elastic deformation and rapid stress drop. A stress surge occurs near the peak stress due to specimen slip and crack initiation. The acoustic emission signals increase significantly before and after the peak stress. The cumulative ring count shows a stepwise jump, and the abrupt increase points of its curve can effectively determine the critical point of crack initiation. The results of RA-AF analysis show that the proportion of shear cracks is the largest when inclination angle of joint is 30°, and tensile failure dominates when inclination angle of joint is 45°. With the increase of inclination angle of joint, the crack propagation mode transforms from tensile-dominated to tensile-shear composite, and then back to tensile-dominated. The FRACOD simulation results show that with the decrease of stress ratio, the horizontal stress significantly restrains the initiation and propagation range of cracks. The increase in horizontal stress significantly changes the failure mode of the rock mass by inhibiting the propagation of tensile cracks. The results reveal the mechanism of joint inclination angle on crack propagation and damage evolution of rock bridge structures, providing a theoretical basis for stability analysis of deep underground rock engineering.

In high-altitude cold regions, complex physicochemical processes such as water-ice phase transitions, ice wedging, and filler dissolution/crystallization occur within rocks, which can easily lead to irreversible damage in rocks with filling fractures, seriously threatening the safety and stability of open-pit mine slopes and transportation infrastructure in these regions. Taking frozen sandstone with filling fractures (FSFF) as the research object, the acousto-optic combined testing technique was employed to investigate the effects of fracture length and fracture angle on the macroscopic mechanical properties, surface strain field, and acoustic emission (AE) parameters of the rock samples. The results show that as the fracture length increases, the compressive strength of the rock samples exhibits a continuously decreasing trend, and the crack propagation in the rock samples is dominated by S1 and S3 type shear cracks and M type tensile-shear mixed cracks. When the fracture length is short, the sharp increase in the AE ring count of the rock samples is concentrated in the crack propagation stage. As the fracture length increases, the phenomenon of the sharp increase in the ring count extends to the elastic stage and the crack propagation stage. With the increase in the fracture angle, the compressive strength of the rock samples first decreases and then increases. The number of sharp increase events in the AE ring count within the rock samples increases, and the spatial distribution of AE events becomes increasingly dispersed. The crack propagation in the rock samples is dominated by S1, S2, and S3 type shear cracks and M type tensile-shear mixed cracks. The failure mode of FSFF is primarily shear rupture. The lower the compressive strength of the rock sample, the greater the proportion of internal shear cracks. The research results can provide a theoretical basis for the engineering stability assessment of fractured rock masses in cold regions.

To reveal the tensile fracture and instability collapse mechanism of granite roofs in deep mining, three types of samples, namely fine-grained Luotian granite, coarse-grained Golden Ma granite, and medium-grained Yunfu granite, were selected for three-point bending tests. Combined with acoustic emission monitoring technology, the bending strength, dominant frequency distribution, damage evolution, and crack propagation patterns were systematically investigated. The results show that the bending strength of granite exhibits a significant particle size effect. The fine-grained Luotian granite has the highest strength of 17.79 MPa, with a sudden post-peak stress drop indicating brittle fracture. The coarse-grained Golden Ma granite has the lowest strength of 5.33 MPa, showing pronounced ductility characteristics. The strength of medium-grained Yunfu granite lies between the above two rock types, reaching 16.04 MPa, and exhibits brittle-ductile transition behavior after the peak. The dominant frequency signals of acoustic emission mainly appear near the peak load and in the post-peak stage, forming three main frequency bands of 0-40 kHz, 50-80 kHz, and 130-180 kHz. The high-frequency signals (130-180 kHz) of Luotian granite surge before the peak, while the dominant frequencies of Golden Ma granite and Yunfu granite are concentrated in the low-frequency band (0-40 kHz) after the peak. The damage evolution of granite undergoes three stages: initial damage, stable development, and accelerated development. Damage accumulation is highly concentrated in the post-peak stage. Golden Ma granite has the highest damage proportion in the post-peak stage, and Luotian granite releases the largest strain energy per unit damage. RA-AF crack mode analysis indicates that the failure of the samples is dominated by tensile cracks, and the proportion of tensile cracks is negatively correlated with mineral grain size. The proportion of tensile cracks in Luotian granite is 3.17 and 6.15 percentage points higher than that in Yunfu and Golden Ma granite, respectively. The quantitative early warning method for roof instability based on dominant frequency signals can provide a theoretical basis and engineering guidance for roof stability evaluation and dynamic disaster prevention and control in deep mining.

In order to investigate the mechanical properties and permeability evolution of limestone with parallel double fissures during complete stress-strain processes before and after grouting, the complete stress-strain seepage tests was carried out on limestone with 45° parallel double fissures before and after grouting under the confining pressure of 10 MPa, 20 MPa and 30 MPa. The test results show that the strength of limestone with parallel double fissures before and after grouting increases nonlinearly with the increase of confining pressure, but the permeability decreases with the increase of confining pressure. Under the same confining pressure conditions, the strength of the specimens after grouting is significantly improved compared with that before grouting. Before grouting, the permeability of parallel double fissures specimens showed a "double peak" phenomenon. After grouting, the grout filled the cracks of the specimens, enhanced the bonding force between the fissure surfaces, changed the geometric shape and mechanical properties of the fissures, thus reducing the occurrence of "double peak" phenomenon. Compared with the specimens before grouting, the pre-peak permeability of the specimens after grouting decreased slightly, but the post-peak permeability decreased significantly. The five key permeability values of the two types of specimens gradually decrease with the increase of confining pressure. Under the same confining pressure, the key permeability values of the specimens after grouting are significantly lower than those of the ungrouted specimens.

The "double carbon" goal puts forward the dual requirements of low-carbon transformation and ecological protection for the sustainable development of open-pit coal mines. Geological disaster prevention and mining area ecological restoration as its core issues need to adapt to new development needs. In view of the contradiction between energy security and low-carbon development faced by open-pit coal mines under the goal of "double carbon", the research progress of geological disaster prevention and ecological restoration was systematically discussed. In the field of geological disaster prevention, the evolution of traditional disaster characteristics and the emergence of new disasters under low-carbon orientation were analyzed, and the application results of energy-saving monitoring technology, carbon footprint-oriented early warning model and green support technology were sorted out. In terms of ecological restoration, the development status of carbon sink function research, low-carbon ecological restoration technology and carbon sink evaluation method of vegetation-soil system were summarized. On this basis, the existing problems such as technical bottlenecks (conflict between traditional technology and low-carbon goals, difficulty in collaborative carbon sink efficiency and engineering stability, insufficient technology integration, etc.), lack of management mechanism (cross departmental policy barriers, ambiguous rights and responsibilities of stakeholders, lack of regional collaborative, etc.) and insufficient policy support (fragmented policy system, disconnection in standard coordination, imperfect incentive and restraint mechanisms, etc.) were further analyzed. Finally, the three transformation paths of technology (building a low-carbon collaborative technology system), management (establishing a carbon-oriented collaborative mechanism) and policy (improving the low-carbon support and guarantee system) were prospected, which provides a theoretical reference for the collaborative development of "disaster prevention-promoting restoration-carbon sink" in open-pit coal mines.

Inclined shaft hoisting conveyances are characterized by heavy payloads and high operating speeds, which generate tremendous impact forces upon braking during a runaway event. However, existing runaway protection devices primarily rely on passive safety facilities within the shaft for interception. They are unable to adapt to the dynamic variations in impact energy, failing to achieve effective energy absorption. To address this issue, a design and optimization method for an adaptive multi-stage buffered inclined shaft hoisting conveyance was proposed, aiming to achieve mechanical braking and the staged absorption of impact energy following a runaway event. Based on this structure, a multi-body coupled impact dynamics model of the multi-stage buffered hoisting conveyance and the inclined track was established. The effect of multi-stage buffering on the braking impact force of the hoisting conveyance system was investigated, and the stiffness of the buffer springs was optimized based on the Sequential Quadratic Programming (SQP) algorithm. The results indicate that, compared with the unbuffered structure, the multi-stage buffered structure reduces the impact force by 24.5%, significantly decreasing the impact response, presenting smaller residual oscillations, and yielding a smoother curve. After the spring stiffness is optimized by the SQP algorithm, the impact force of the hoisting conveyance and inclined track system decreases by 35.5% and 14.7% respectively, compared to the unbuffered system and the pre-optimization multi-stage buffered system. This improves the absorption efficiency of impact energy, enhances the system's impact performance, and results in a more stable secondary impact force. The research findings provide a theoretical basis for the impact-resistant design and safe braking strategies of inclined shaft hoisting conveyances.

To address the challenges of insufficient mobility of traditional stationary oxygen stations and the limited operational duration of portable equipment such as carbon fiber oxygen cylinders and oxygen bags in high-altitude areas, a novel emergency air respirators was developed. The apparatus adopted intelligent mixed oxygen supply technology and integrated a spiral oxygen-nitrogen separator. It effectively reduced the overall volume while improving the gas separation efficiency, achieved highly efficient oxygen-nitrogen separation, and continuously and stably provided breathing gas with an oxygen concentration of 21%. Tailored for complex operating conditions such as low pressure and low temperature in high-altitude regions, the system overcame the shortcoming of insufficient operational duration of traditional equipment through integrated and optimized design. The test results indicate that under the high-altitude condition of 5 445 m, after adopting the novel emergency air respirators, the blood oxygen saturation of users increases from a dangerous level of approximately 68% to a relatively safe level of 92%. The maximum battery duration reaches (296±6) min (altitude -154 m), and the apparatus possesses advantages such as high oxygen production efficiency, rapid response, easy operation, as well as safety and energy conservation. The research results provide a more reliable safety guarantee for emergency rescue and underground operations in high-altitude mining areas.

The rapid development of autonomous driving technology has continuously expanded its application scenarios, and unmanned driving in mines has become an important direction in intelligent mine construction. Aiming at the problems of complex underground working environments, high manual labor intensity, and prominent safety risks, an unmanned driving system for underground electric Load-Haul-Dump (LHD) machines was designed and implemented by integrating autonomous driving and remote control technologies. The system adopted an operation mode of "remote-controlled loading, autonomous driving for transportation and unloading", realizing the full-process unmanned operation of LHD machines in underground roadway environments. Field industrial test results show that the average lateral tracking error of the system during operation is controlled within 0.30 m, the positioning loss probability is approximately 0.11%, and the average communication latency is less than 5 ms. The system also possesses good safety assurance capabilities, with the access control system and anti-collision detection module effectively handling emergency situations. The research results verify the stability and practicability of the system in underground mine environments, which can effectively reduce miners'labor intensity and improve underground working conditions.

To solve the problems of strong subjectivity, poor dynamic adaptability, and low evaluation efficiency in the resource development of closed/abandoned mines, a multi-dimensional evaluation index system with a three-tier framework of "target layer, criterion layer, and index layer" was constructed under the guidance of the collaborative concept of "energy-oriented, resource-oriented, and function-oriented" utilization. By integrating algorithms such as Analytic Hierarchy Process (AHP), Light Gradient Boosting Machine (LightGBM), and Isolation Forest, an intelligent model for dynamic weight optimization and consistency check was constructed. The intelligent evaluation system for closed/abandoned mine resources based on adaptive AHP was developed using Java language, with the Vue. js and Spring Boot frameworks, and technologies including MySQL, Redis, Apache POI, and Docker. In the system, functions such as data import, hierarchical analysis calculation, and result visualization are realized, and the shortcomings of traditional evaluation methods, such as static weights and excessive manual intervention, are overcome. A case study was conducted under the actual conditions of the Longdong Coal Mine. The results show that the system can accurately reflect the characteristics of the mine resources and exhibits good practicality. The research results can provide a replicable technical path for the intelligent evaluation of closed/abandoned mine resources.

In view of the mining integrated energy system suffers from multiple source-load uncertainties including fluctuating wind and photovoltaic output, dynamic variation of mine production load and unstable associated energy output after the integration of new energy such as wind power and photovoltaic power, which greatly increases scheduling complexity and makes it difficult to guarantee energy efficiency, a scheduling method integrating uncertainty analysis and multi-level collaboration optimization was proposed. Firstly, an energy flow model covering source-grid-load-storage was constructed, and a multi-scale source-load uncertainty interval model was established to quantify fluctuation risks. Secondly, a multi-time scale collaborative scheduling framework of day-ahead, intra-day slow layer and intra-day fast layer was designed, and the NSGA-Ⅱ algorithm was improved by adopting a time series segmentation strategy to realize the global optimization of operational cost and energy efficiency. Simulation results based on the integrated energy system of Datong Mining Area show that the system operation cost is reduced to 170 500 yuan, the renewable energy utilization rate is increased to 89.1%, the carbon emission is decreased to 6.83 t, the load tracking error is cut down to 18.9 kW, and the peak shaving rate reaches 17.2%. In addition, the average single-time period solution time of the scheduling method based on series segmentation NSGA-Ⅱ is only 7.0 ms, which is significantly superior to that of traditional methods. The research results verify the effectiveness of the energy scheduling method integrating source-load uncertainty and multi-level collaboration in improving the operational efficiency, energy conservation and emission reduction level of mine energy systems. Feasible scheduling strategies and algorithm support are provided for the efficient and low-carbon operation of mining integrated energy systems under complex uncertain conditions.

In the process of mine exploration and production, energy consumption loads such as drilling rigs and ventilation are intertwined with building heating and hot water loads, and the mining area is rich in resources such as mine water waste heat and associated gas. Traditional energy scheduling methods are difficult to effectively deal with them. Therefore, an optimal scheduling model of mine integrated energy system (MIES) integrating photothermal power station and multi-source heat pump was proposed to improve energy efficiency and low-carbon level. The photothermal molten salt heat storage and multi-source heat pump group work together to build an electric-thermal collaborative supply network that adapts to the rhythm of mine production, and the multi-objective particle swarm optimization algorithm was introduced to optimize the economy and low carbon of the system. The results show that the weekly operating cost of the mine energy system is reduced to 331 700 yuan, the total carbon emission is 39.44 t, and the renewable energy consumption rate reaches 92.54%. The system effectively ensures stable heating in the mining area, with temperature fluctuations controlled within ±1.2 ℃. The utilization rate of the photothermal heat storage device reaches 92.17%, and the average coefficient of performance of the heat pump group rises to 4.47. The proposed model can fully integrate and utilize multi-energy sources in mining areas, effectively improving the economic and environmental benefits of the mine production system, and providing crucial technical support for the construction of green mines.

To improve the capability of Fiber Bragg Grating (FBG) sensors in mine safety monitoring systems to address the cross-sensitivity problem of temperature and strain, a high-precision cross-sensitivity decoupling monitoring model was constructed by integrating a dual-grating temperature compensation method and a Gaussian process regression modeling method improved by the particle swarm optimization algorithm. The experimental results indicate that the proposed method outperforms traditional methods in both wavelength shift data fitting and prediction accuracy. The monitoring system achieves high-precision measurement of temperature and strain data in the mine environment, with the minimum monitoring error being only 0.04 mm and the fitting degree R² reaches 0.912. The system realizes high-precision dual-parameter monitoring in the mine environment, where the monitoring accuracy of temperature and strain reaches 0.961, and the data transmission rate increases by 36% compared to photosensitive and electronic sensors. This demonstrates that FBG sensors possess certain advantages in the dimensions of acquisition accuracy and real-time performance. The research results provide a reusable theoretical framework for innovation in mine safety monitoring and lay a methodological foundation for the evolution of intelligent monitoring systems.

To achieve the effective recovery of iron resources from solid waste, a combined recovery process of reverse flotation, magnetizing roasting, and magnetic separation was proposed, taking a low-grade iron tailings resource in Jingzhou, Hubei as the research object, to efficiently separate the weakly magnetic iron resources in the tailings. Mineralogical analysis indicates that the iron grade of the raw ore is 18.72%, and the ore mainly consists of weakly magnetic hematite and limonite, featuring a fine dissemination size and a high gangue content. Reverse flotation pretreatment was adopted to remove aluminosilicate gangue, thereby reducing the processing volume and energy consumption of subsequent processes. The reverse flotation process parameters were optimized through experiments. Under the conditions of a grinding fineness of 75%, a pulp pH of 9, a soluble starch dosage of 1 500 g/t, and a dodecyl amine dosage of 400 g/t, the iron recovery of reverse flotation roughing reaches 83.07%. After one cleaning stage, the total iron grade of the concentrate increases to 43.60%. Through single-factor experiments, the optimal parameters for magnetizing roasting and magnetic separation are determined as follows: a roasting temperature of 650 ℃, a roasting time of 30 min, a pulverized coal dosage of 6%, and a magnetic induction intensity of 180 mT. This process achieves the directional transformation of weakly magnetic hematite and limonite into strongly magnetic magnetite. After roasting, the magnetic iron grade increases from 0.20% to 43.12%, and the iron grade of hematite and limonite decreases from 38.16% to 1.02%. This combined process realizes the efficient recovery and enrichment of iron resources from the tailings, which provides a technical reference for the resource utilization of tailings.

Hematite is the main associated mineral in a rutile ore deposit in Hebei Province. The rutile particles are fine and intergrown with or enclosed by hematite. Conventional magnetic separation has poor separation effect, making it difficult to achieve effective separation of iron and titanium. Reduction roasting has been proven as an effective technological approach for achieving efficient liberation of fine-grained iron ores from associated gangue minerals. A mineral quantitative automatic analysis system and scanning electron microscope (SEM) were adopted to clarify the mineral composition, element distribution and other information of the samples. The combined process of deep reduction and magnetic separation was adopted to treat the titanium-bearing hematite rough concentrate. Thermodynamic calculation was used to simulate the reaction behaviors of iron minerals and gangue minerals during the reduction process. The optimal experimental conditions were determined as follows: reduction temperature of 1 623 K, reduction time of 120 min, C/O molar ratio of 2.0, and magnetic field intensity of 85 mT. Under the optimal conditions, the metallization rate of reduced products reaches 78.94%. The total iron grade and total iron recovery of iron concentrate are 89.08% and 88.39%, respectively. The TiO₂ grade and TiO₂ recovery of titanium concentrate are 36.67% and 71.88%, respectively, showing favorable mineral processing and smelting indexes.