CHINA MINE ENGINEERING

Abstract:To address the optimization of medium-deep hole blasting parameters following the implementation of charging trucks in Chengchao Iron Mine, this study established a fluid-structure coupling model using ANSYS / LS-DYNA based on the existing blasting scheme. Seventeen different configurations combining four borehole bottom spacings and four staggered uncharged section layouts were compared and analyzed in terms of fracture zone mass, explosive consumption per unit, and effective stress. The results demonstrate that the optimal blasting parameters are a borehole bottom spacing of 2 m with uncharged sections of 2 m and 6 m. This configuration achieves a fractured zone mass of 820 tons, representing a 38. 5% improvement over the original scheme ( 592 tons ), while maintaining the lowest explosive consumption per unit and ensuring that the effective stress in the ore rock exceeds the yield strength. The optimized approach reduces both drilling work and explosive consumption without compromising blasting effectiveness, offering valuable insights for optimizing medium-deep hole blasting parameters in similar mining operations.

Abstract:In response to the problem of determining the reasonable position of the access route during the mining of a steeply inclined medium thick ore body in a certain iron mine using the Sublevel caving method , combined with the similarity simulation and numerical simulation (PFC3D) method, a study was conducted on the optimization of the position of the access route along the strike of the ore body. Taking the dip angle of the ore body as 85° and the average thickness of 20 m as the research object, there is a problem of residual ore recovery in the ridge area of the conventional straight layout approach. Therefore, a comparative analysis is conducted on the mining indicators and loose material transportation rules of the upper and lower segmented straight layout (staggered distance of 0 m) and staggered layout (staggered distance of 3 m, 6 m). The research results show that the mining effect is better when the upper and lower segmented access roads are horizontally staggered by a distance of 6 m: in numerical simulations, the ore recovery rate reaches 86. 34% and the ore impoverishment rate drops to 17. 07% , while in similar experiments, the ore recovery rate is 84. 79% and the ore impoverishment rate is 15. 55% , and the trend of the two results is consistent. This study effectively solved the problem of difficulty in recovering residual ore from the ridge of the upper segmented mining route in the lower segmented mining.

Abstract:To address the issue that the traditional ellipsoid model cannot accurately describe the complex morphology of the draw body (characterized by a coarse upper part and a fine lower part) during ore drawing in a single drift with a large-scale structure, this study established a large-scale physical ore drawing model to conduct single-drift ore drawing experiments, based on the predicted distribution of blasted fragment sizes of actual ore-rock samples from a mine. By arranging marker particles in layers and recording the ore drawing process, a butted model of double semi-ellipsoids of revolution was innovatively adopted to characterize the morphology of the draw body, and the Levenberg-Marquardt least squares algorithm was applied for high-precision fitting (with correlation coefficients generally ＞ 95% ). The experimental results show that: ① The volume of the draw body (V) exhibits a power function relationship with the ore drawing height (h) and the drift opening width (w), expressed as V = 30. 42 × (h / w)2. 626 (R ² = 0. 999 2), and the stability is poor when the relative height h / w ＜ 4; ② The ore drawing height (h) shows strong linear relationships with the major semi-axis (a) and minor semi-axis (b) of the draw body, which are a = 0. 513 6h-5. 043 (R ² = 0. 999 3) and b = 0. 090 8h + 3. 627 3 (R ² = 0. 999 2) respectively; ③ The dilution rate (p) increases linearly with the drawn volume (V), following the relationship p = 8. 941 × 10-5 V-32. 38 (R ² = 0. 913 3). Furthermore, a scale conversion method for on-site engineering application was proposed. Based on the geometric similarity criterion, the concept of dimensionless volume was introduced to realize the conversion of experimental data to the on-site scale, ensuring the effective application of theoretical results in practical scenarios. This study quantitatively reveals the morphological characteristics of the draw body and the intrinsic relationships between its key parameters under the condition of single drift with a large-scale structure. The established mathematical models can be directly used to predict the draw body volume and expected dilution rate under specific ore drawing heights and drift widths, providing an important theoretical basis and operational guidance for on-site precision control of ore drawing processes, optimization of ore recovery, and reduction of dilution.

Abstract:Rock tunnel excavation is carried out within the range of close range coal seams. Due to the formation of goaf after the completion of close range coal seam mining, severe deformation of adjacent tunnels is caused. The excavation of the Shimen main roadway at the boundary of the 15th mining area in Tucheng Mine is a typical close range coal seam group roadway excavation. After the completion of the mining of the 12th coal seam in the lower layer, a goaf is formed, and the overall roof collapses, causing severe deformation of the Shimen main roadway at the boundary of the 15th mining area. In response to the problem, numerical simulation analysis shows that current support measures are prone to causing bottom bulging in the roadway, with a maximum bottom bulging amount of 93. 9 mm. A roof cutting technology process has been developed, and through comprehensive calculations, the cutting position point is at the 151212 mining face transportation roadway, with a cutting height of 15 m. After the implementation of roof cutting, the roadway will be observed in the later stage, and the maximum force on the roadway anchor cable is 160 kN, with a maximum displacement of 155 mm, and overall stability. The research results and methods have certain guiding significance for roof cutting in other mines.

Abstract:Aiming at the stability problem of complex goaf caused by deep mining in Hebian mining area of Nanwenhe Tungsten Mine in Yunnan province, this study builds a refined three-dimensional geomechanical model based on FLAC^3D , and systematically analyzes the characteristics of stress redistribution, displacement evolution and plastic zone expansion of surrounding rock in goaf. The results show that the vertical stress in the goaf is concentrated in the middle of the pillar (maximum 40 MPa), the roof stress is low (5 MPa), and the pillar and surrounding rock have no significant plastic failure. The maximum displacement of the roof is 18. 06 mm, the maximum displacement of the bottom heave is 0. 64 mm, and the overall deformation is small and tends to be stable. The plastic zone shows partial tensile failure of the roof, but the stability of the pillar dense area is good. Through continuous simulation monitoring of 10 monitoring points on the roof, it was further confirmed that the roof stress (with stable values all less than 1. 2 MPa) and displacement tended to be stable in the later stage of calculation. Numerical simulation shows that the goaf has high stability under the existing filling conditions, which can provide theoretical support for disaster prevention and control and green mining in hydrologically sensitive mining areas.

Abstract:To identify and evaluate the stability of the goaf in the Majiadidi tungsten mine, this study conducted a systematic analysis targeting two types of backfilled goafs in the mining area. The analysis integrated field investigations, three-dimensional numerical simulation, and in-situ monitoring techniques. A refined numerical model of the goaf was established using the coupled 3DMine and FLAC3D method. Initial in-situ stress was determined using the hydrostatic pressure formula to simulate stress, displacement, and plastic deformation characteristics of the roof and floor. Nine monitoring points were deployed in critical roof areas for validation. Results indicate overall stability and safety of the goaf. Field monitoring recorded maximum roof displacement of 24. 11 mm and peak stress of 11. 42 MPa, while numerical simulation projected maximum roof displacement of 25 mm. Both trends align and remain within rock mass safety limits. Stress distribution in the pillar exhibited a “ high in the middle, low at both ends” pattern, with only minor localized shear and tensile failures observed. No continuous plastic failure zones were detected, indicating that the backfilling and sealing measures effectively mitigated risks. These findings provide theoretical support and reference guidelines for evaluating the stability and managing the safety of goaf areas.

Abstract:To investigate the influence mechanism of gob-side filling body properties on overburden stability in gob-side entry retaining, this study combines physical modeling and numerical simulation to identify key parameters affecting overburden stability and analyzes their governing patterns. The results indicate that the compression modulus and supporting strength of the gob-side filling body are the dominant factors controlling overburden subsidence during gob-side entry retaining. Specifically, both parameters exhibit negative correlations with overburden subsidence: as the compression modulus increases within the 0. 5 ~ 1. 2 GParange, subsidence decreases significantly, with optimal suppression achieved between 0. 5 ~ 1. 2 GPa before diminishing beyond 1. 2 GPa; similarly, when supporting strength ranges from 0. 5 ~ 2. 0 GPa, higher strength markedly reduces subsidence, though this effect weakens beyond 2. 0 GPa. This study clarifies the effects of the compression modulus and supporting strength of the gob-side filling body on the variation law of overburden subsidence, laying a theoretical foundation for maintaining overburden stability in gob-side entry retaining.

Abstract:To address industry pain points such as the difficulty in implementing the dual prevention mechanism for mines, data silos, and insufficient safety management efficiency, and to implement the national policy deployment of strengthening mine safety and promoting intelligence, a mine safety intelligent management and control platform based on the integration of digital twin and AI is proposed. The platform integrates diverse safety data from open-pit mines, underground mines, and beneficiation & metallurgy plants, and constructs a three-layer architecture of “ safety monitoring-scenario safety-system application”; AR equipment enables real-time data collection and visualization, AI safety models conduct risk analysis and early warning, and the mine knowledge base provides historical case and regulatory support to build a decision-making center; key technologies such as deep underground high-precision positioning and mine scenario-adaptive AI recognition are conquered. After the platform is put into operation, it is expected to increase hidden danger identification rate by 30% ~ 40% , reduce accident rate by 25% ~ 35% , and shorten the emergency response time for accidents such as water inrush from the industry average of 45 minutes to within 20 minutes. The platform provides a feasible solution for ultra-deep and ultra-large-scale mines, solves problems such as blind spots in manual inspection, and helps transform safety governance towards pre-event prevention.

Abstract:This study takes the geologically complex Qingping Phosphorite Mine in western Sichuan as its engineering context and conducts systematic research on the precise inversion of the three-dimensional stress field and its spatiotemporal evolution mechanisms in deep heterogeneous rock masses under mining-induced conditions. Integrating field measurements via hydraulic fracturing, theoretical analysis, and numerical simulation, this research first employs data from three nearly orthogonal boreholes and introduces a Tikhonov regularization algorithm to improve the traditional least squares method, constructing a high-precision inversion model for the three-dimensional stress tensor that effectively overcomes the ill-posed nature of the inversion process. Subsequently, using the inverted in-situ stress field as the initial condition, the dynamic evolution patterns of the surrounding rock stress field, displacement field, and plastic zone during roadway excavation are revealed through theoretical elastic mechanics analysis and numerical simulation, while a quantitative assessment of rockburst risk is performed based on the tangential stress criterion. The results indicate that the mine’s stress field is dominated by near-horizontal NWW-SEE (N40° W ~ N50° W) tectonic stress, with the maximum principal stress reaching 26. 45 ~ 33. 64 MPa and a stress ratio (σ₁ / σ₃ ) of 1. 6 ~ 2. 0, exhibiting characteristics typical of a reverse fault stress regime. Mininginduced disturbances lead to significant stress redistribution in the surrounding rock, with a tangential stress concentration factor of 2. 0-2. 5 at the mid-height of the roadway ribs. The rockburst risk index (σθmax / σc) is 0. 47 ~ 0. 49, indicating a slight rockburst risk in both mining sections, and the plastic zone extends to 1. 8 ~ 2. 2 times the roadway radius. The systematic methodology of “geological prototype-field measurement-theoretical inversion-spatiotemporal prediction” established in this study enables a comprehensive analysis from static characterization to dynamic evolution of the deep stress field. The research outcomes provide critical scientific evidence and theoretical support for the optimized design and hazard prevention in deep mining engineering.

Abstract:Therefore, taking the open-pit mining project of Gongchangling Iron Mine as the research object, based on quantitative GSI index and Hoek Brown (H-B) strength criterion, the H-B strength parameters were calculated and obtained, and then converted into equivalent Mohr Coulomb (M-C) strength parameters through mathematical fitting method, providing theoretical basis for engineering design and construction. And by introducing the theory of extension and combining various traditional grading methods, a comprehensive evaluation model for rock mass quality is established based on the D-S evidence theory and the fusion of various rock mass quality grading results. The research results indicate that the use of rock acoustic testing reveals the distribution characteristics of the integrity and weathering degree of the target borehole rock mass, providing key geomechanical basis for the stability assessment and mining design of mining engineering; A quantitative evaluation system combining Geological Strength Index (GSI) and Hoek Brown (H-B) strength criterion was established to accurately determine the H-B strength characteristic values of the target rock mass. Based on numerical fitting, the equivalent Mohr Coulomb (M-C) strength parameters were further derived, laying a reliable data foundation for numerical simulation of rock mass stability; Using RMR, Q, BQ, extension theory, and D-S evidence theory for comprehensive evaluation, multi-dimensional grading is carried out to ultimately determine the quality level of each target rock mass.

Abstract:In blasting engineering, the blasting lumps size are the key index to evaluate blasting effect and optimize blasting parameters. The key to the blasting lumps size recognition is to fully extract the effective feature information of complex rock image, and then accurately segment the image. The serious stacking between ore and rock is the main reason for the inability of accurate segmentation. The traditional image segmentation algorithms are usually based on threshold, edge detection and so on. These methods have the defects of poor accuracy, weak robustness and low practicability. Combined with the actual needs of mine blasting pile block recognition, an improved mask RCNN ore rock segmentation model is proposed. The noise reduction image of the protected edge is generated by bilateral filtering, and the noise reduction image is used as the data set of mask RCNN to generate a learning model for ore rock segmentation. Compared with the traditional OTSU and Canny edge detection algorithms, this algorithm has high accuracy, strong practicability and better robustness; Compared with UNET algorithm, it solves the local segmentation defect of UNET on the premise of ensuring the segmentation accuracy. The experimental results show that the pixel difference curves of manual segmentation and model segmentation fit well, which has a certain engineering significance for the identification of the blasting lumps size recognition.

Abstract:Water inrush in shafts is one of the key disasters to be prevented during shaft construction. To avert water inrush accidents, advance detection in shafts must be enhanced during the excavation of ultra-deep shafts. Taking the advance detection at the 1 464. 5 m depth of the Sanshandao ultra-deep shaft as an example, the Transient Electromagnetic ( TEM) method and the seismic reflection method were employed to detect the distribution of water-bearing fracture zones in the excavation face. Survey systems for both TEM and seismic reflection were set up according to the face conditions. Field data were acquired, processed, and visualized into result maps. Integrated with on-site geological and hydrogeological data, distinct low-resistivity anomalies and wave impedance interfaces were identified within the depth ranges of 1 492. 5 m to 1 507. 5 m and 1 517. 5 m to 1 529. 5 m. These anomalous zones were delineated and interpreted as water-bearing fracture zones. Field excavation results confirmed the accuracy of the detection, demonstrating that the combined TEM and seismic reflection method can effectively achieve advance detection in ultra-deep shafts.

Abstract:This study aims to explore the application of the NSR(Net Smelter Return) method in open-pit optimizing of polymetallic orebodies to improve resource utilization efficiency and economic benefits. Given the characteristics of polymetallic orebodies, such as complex orebody morphology and significant grade variations, this research establishes a geoogical model based on the NSR method and optimize the open-pit mining boundaries. Research shows that: (1) The NSR method optimizes open-pit by calculating the net revenue of ore blocks, taking into account the geological characteristics and economic factors of the ore comprehensively, making the boundary delineation more scientific and reasonable. (2) NSR can be used to determine the mining priority of different ore bodies, providing a basis for investment decisions. This helps mine to make scientific decisions in a complex market environment, thereby improving overall economic efficiency. (3) Compared to the equivalent grade pit optimization method, the NSR boundary optimization method extracts less ore, with higher grade and greater revenue, thereby optimizing resource utilization and reducing the mining of low-grade ore. This is particularly suitable for dealing with complex ore bodies or low-grade ore deposits and can significantly improve resource utilization. Additionally, the NSR method exhibits good adaptability and flexibility in optimizing open-pit boundaries for polymetallic orebodies, providing a new approach for open-pit mine optimization planning. This study has important theoretical and practical implications, offering valuable insights for the optimization of open-pit mining in polymetallic orebodies.

Abstract:In order to evaluate the application effectiveness of HPGR wet screening closed-circuit process and provide valuable industrial application data for similar copper beneficiation, this paper systematically studies and analyzes the application of HPGR closed-circuit wet screening process in a copper beneficiation. The industrial practice of High-Pressure Grinding Roll ( HPGR) closed-circuit wet screening process has proved that compared with the three-stage one closed-circuit process for treating the same ore, the fine particles are significantly increased, the particles below 3 mm are increased by 24. 90% ; the unit energy consumption is reduced by 2. 28 kW·h per ton of ROM, and the total power consumption is reduced by 10. 5% . The reduce of materials consumption is remarkable. The steel ball consumption is reduced by 15. 8% . The flotation recovery is increased by 0. 5% ; However, the service life of the HPGR studs was relatively low, about 6 500 h.

Abstract:In order to solve the problem that the fine dispersion particle size of copper minerals in a large porphyry copper mine abroad and the high content of gangue minerals prone to mudization affect copper recovery, a separation test study was carried out. The research results show that the closed-loop flotation process of “ three rounds of rough selection-centralized classification of coarse and concentrate, re-grinding and re-selection ” is adopted. Under the conditions that the fineness of coarse selection grinding of-0. 074 mm accounts for 62% , the dosage of lime is 1 500 g / t, the dosage of the collector ethylene xanthate for coarse selection Ⅰ + coarse selection Ⅱ = 20 g / t + 10 g / t, the concentration of the flotation pulp is 33% , the flotation time is 3 minutes, and the fineness of coarse concentrate regrinding of-0. 038 mm accounts for 90% . The copper grade of the available copper concentrate is 26. 89% and the recovery rate is 94. 05% . The molybdenum grade of 0. 43% and the recovery rate of 72. 97% are good indicators, achieving the comprehensive recovery of copper and molybdenum.