CHINA MINE ENGINEERING

Abstract:To address the issue of the excessive width of coal pillars in roadway section affected by multiple mining under the condition of thick hard roof, based on the engineering background of Dongtai Xinyuan Coal Mine 10109 transport channel, theoretical calculation and analysis, Flac3D simulation and engineering practice were adopted to carry out top cutting and pressure relieving for thick hard roof. It is determined that the reasonable remaining width of coal pillar in roadway section affected by two dynamic pressures is 16.5m. The findings indicate that the cutting height is set at 27 meters with an angle of 0°. The numerical simulation demonstrates that when the coal pillar width is below 16 meters, the coal pillar has high stress concentration and serious plastic failure after being affected by two mining movements. When the width of coal pillar is higher than 16m, the elastic core area within the coal pillar exceeds 50%, ensuring the stability of the surrounding rock in the roadway. Therefore, a support plan utilizing a “Strengthen the side to protect the top” has been suggested. The maximum surface displacement of the top and bottom plate of 10109 transport trough under the influence of one mining is 165mm, and the maximum surface displacement of the two sides is 118mm. The coal pillar in the 16.5m wide section, along with the combined support technology, can effectively manage the deformation of the roadway's surrounding rock under dynamic pressure.

Abstract:In order to obtain the parameters of medium and long hole blasting in Tonglvsshan Copper Iron mine, based on Livingston blasting funnel theory, this paper deduces the theoretical formula of cylindrical charge suitable for medium and long hole blasting, and carries out a series of blasting funnel tests under certain conditions of ore, rock and explosive properties. The results show that the best central depth of charge is 0.42m, the best volume of blasting funnel is 0.016m3, the best radius of blasting funnel is 0.45m, and the minimum resistance is 0.79m. The optimum hole base distance of Tonglvshan Copper Iron Mine is 0.8~0.9m in the same section blasting funnel test. Based on the derivation formula of cylindrical charge blasting funnel, the optimal hole row spacing and hole bottom spacing are 1.62m and 1.65~1.85m respectively.

Abstract:This paper primarily addresses the characteristics of low permeability and difficulty in water injection in coal seams of the mines under Shanxi Xinyuan Coal Industry Co., Ltd. By employing the method of mechanical cavity formation, the permeability of the coal seams is enhanced to achieve the purpose of water injection for dust prevention. Firstly, based on the field conditions, numerical simulations of cavity formation drilling were conducted using the PFC2D5.00 software. The study found that under a 500mm diameter drilling hole, the fractures initially distribute uniformly and then spread in the vertical direction. Within the elastic region, the porosity in the horizontal direction shows an increasing trend, while in the vertical direction, it shows a decreasing trend. Secondly, considering the field environment and relevant regulations, appropriate drilling intervals, cavity formation intervals, and cavity lengths were selected. Finally, suitable water injection pressure, water volume, and injection time were calculated based on empirical formulas. By analyzing the water injection effect of the coal seams after mechanical cavity formation, the results indicate that after ordinary water injection, the average increase in coal body moisture is 1.53% to 2.35%, with an average increase of 0.23% to 1.05%. After implementing mechanical cavity formation, the average coal body moisture measured is 4.83% to 7.02%, with an average increase of 3.53% to 5.75%. Through comparison, it can be seen that mechanical cavity formation significantly increases the moisture content of the coal body. The more thoroughly the coal body is moistened, the greater the increase in moisture, and the larger the average increase in coal sample moisture.

Abstract:This paper took the 110303 return airway of a certain company as the research object and researched the influence law of working face mining on the stability of roadway surrounding rock. Firstly, the paper investigated the problem of large deformation and long duration of deformation of the roadway gang. Then the horizontal and vertical stresses of the roadway protection coal pillar were taken as the research object, the coal pillar stress division of the roadway was carried out, the stress criterion of the coal pillar stress of the roadway was proposed, and the characteristics of each section are described. According to the characteristics of the surrounding rock deformation of the roadway gangs affected by the mining of adjacent working faces, the evolution characteristics of the coal pillars in the mining roadway were analyzed, and the unsteady zone evolves to the fracture zone, and the mining zone gangs are destroyed when the stability zone evolves to the unsteady zone. The control scheme of anchoring anchor and cable anchoring section and deep stability zone of coal pillar was proposed, and the problem of large deformation of mining roadway was controlled in a targeted manner, which provides theoretical and practical basis for similar engineering conditions.

Abstract:The dynamic stability of slopes is a critical concern in mining engineering. This paper aims to analyze the seismic dynamic stability of the slopes at the Panzhihua-Xichang regions open-pit mine using UAV aerial photogrammetry combined with FLAC3D numerical simulation software. High-precision image data was obtained using UAV oblique photogrammetry, and the Midas GTS-NX software was employed to convert the photogrammetric data into mesh files recognizable by FLAC3D. By setting appropriate model parameters, the dynamic response of the slope under seismic conditions was simulated. The results indicate that seismic activity significantly impacts slope stability, with safety factors of 1.289 before and 1.199 after the seismic event. The east slope exhibited substantial displacement and settlement, reaching 62.50mm and 62.59mm, respectively, with plastic zones predominantly concentrated at the slope crest and toe, indicating a landslide risk. Therefore, it is recommended to strengthen routine monitoring and support of the east slope to ensure safe mining operations.

Abstract:In order to study the variation law of the influence of rainfall and slurry drainage on the strength of backfill during the construction of open pit backfill discharge, based on the engineering background of Dagushan open pit in Anshan City, Liaoning Province, two different slurry ratios were immersed in water tests and seven different types of rainfall were applied to obtain the compressive strength and strength reduction law of backfill under different conditions. The results show that when the immersion time is 1h, the compressive strength of backfill decreases most obviously, but the reduction range of compressive strength decreases with the increase of immersion time. Rainfall intensity has a significant effect on the early compressive strength of the backfill body (3d, 7d). The greater the rainfall intensity, the higher the reduction degree of the early compressive strength of the backfill body, and the lower the compressive strength. When the rainfall exceeds 7mm/d for three consecutive days, the discharge construction should be stopped.

Abstract:In order to study the depth and failure mode of the plastic zone in the excavation process of a vertical shaft, a study was conducted on the depth and failure mode of the plastic zone in the surrounding rock of a certain metal mine in the 1000-1200m section of the well engineering through geological investigation, theoretical analysis, numerical simulation, on-site testing and other technical means. The results show that the engineering geological conditions in the 1000-1200m section are good, and the depth of damage to the surrounding rock of the wellbore is 2.94m at 1000m, 2.23m at 1100m, and 2.45m at 1200m, respectively. Further theoretical calculations and numerical simulations were conducted to determine the failure mode of the surrounding rock of the wellbore, all of which were determined to be ear shaped failure. By studying the forms and depths of wellbore damage during excavation, scientific basic parameters can be provided for the lining and support of the surrounding rock of the wellbore, ensuring safe and reliable excavation of the wellbore.

Abstract:Taking the main shaft tower of a certain super large iron mine as an example, this paper explores the design process of the shaft tower structure. This article elaborates on the process of arranging the plan and vertical layout of a super large well tower, introduces the load values and working condition combinations of the well tower, provides optimization measures for the seismic unfavorable situation of the well tower, uses YJK for small earthquake elastic analysis, verifies it using MIDAS Building, and supplements the calculation with elastic time history analysis. Provide reference and assistance for the design of super large well towers in the future.

Abstract:To explore the link between dynamic modulus and damping modulus of tailings sand, taking into account its fines content, the samples were conditioned under a specified dry density and isobaric consolidation, across different cyclone classification scenarios. This analysis sought to clarify how fines content affects the dynamic and damping behaviors of tailings sand, resonance column tests were conducted on unsaturated tailings sand samples with different fines contents. Test results indicated that at the same fines content, the maximum value of the dynamic shear modulus follows the law of variation of the ambient pressure. At the same pressure, the maximum dynamic shear modulus of the tailings sand showed a decreasing trend with increasing fines content, indicating that fines content has a certain effect on the shear damage resistance of the tailings sand. At the same fines content, the maximum damping modulus of the three tailings sands decreased with increasing ambient pressure. Due to the critical fines content, the maximum attenuation coefficients of the tailings sands tend to increase and then decrease with a gradual increase in fines content. The study′s outcomes furnish essential information for evaluating how tailings with varying fines content respond dynamically. These insights form a cornerstone for designing and managing intermediate tailings ponds in earthquake-prone areas.

Abstract:Through the flotation test of bastnaesite pure mineral, the paper investigated the effects of metal ions,incuding calcium、magnesium、iron in the pulp and slurry temperature on the floatability of fluorocarbon cerium ore and regulaiton, with ssodium oleate as the collector. The experimental results showed that calcium、magnesium、iron ions and slurry temperature had different degrees of inhibition on the flotation process of bastnaesite with sodium oleate as collector.The floatability of inhibited bastnaesite by calcium and magnesium ions can be activated by EDTA、 lead nitrate、sodium dodecyl sulfonate as activators.

Abstract:The lithium containing ore slurry obtained from a low-grade spodumene mine in Xinjiang through hydraulic cyclone desilting was used in this work. The influences of particle size distribution, flotation reagents, and separation process on the lithium recovery were investigated. The results showed that the Li₂O content in the mud sample was 0.69%, and the mainly lithium-bearing minerals was spodumene. The mineral particle size was very small (D₉₇=9.18μm), suggesting that it an ultra fine and difficult to separation low-grade mineral fine mud. Under the laboratory closed circuit conditions, with the usage of the Na₂CO₃-NaOH-CaCl₂ composite modifier as slurry adjustment and EF1116 as lithium minerals collector, a lithium concentrate with a Li₂O grade of 3.89% and a recovery rate of 52.95% was obtained relative to the feeding mud when it was used a rapidly slurry adjusting-the one rough flotation—one sweep flotation-two cleaner flotation-one selected-sweep flotation of intermediates stepwise separation process. The relative enrichment ratio of lithium mineral separation reached 5.6, which is 11.5 percentage points of Li₂O recovery ratio higher than that of the one rough selection-one sweep flotation- two cleaner flotation of intermediates sequential regurgitation process. This study provides technical and data references for the recovery of lithium from the abandoned mineral fines produced by hydraulic cyclone desliming.

Abstract:The Yagongtang pluton is closely related to the formation of deep lead-zinc copper iron polymetallic deposits. This article takes the Yagongtang rock mass as the research object, studies the petrological and geochemical characteristics of the rock mass, and explores its diagenetic mechanism. Research has shown that the lithology of the Yagongtang rock mass is relatively simple, mainly composed of granodiorite, belonging to the quasi aluminum rich sodium high potassium calcium alkaline rock series. The rock mass rises along structural fractures in an environment transitioning from compression to extension, and forms by invading the near surface structural space. The diagenetic material is a crust mantle mixed type, belonging to the typical Type I granite. The distribution curve of rare earth elements shows a right skewed pattern with high left and low right, indicating that light rare earths are relatively enriched and differentiated from heavy rare earths. The fractionation of light and heavy rare earths is relatively obvious, indicating a strong loss of heavy rare earths and enrichment of light rare earths.

Abstract:Mier deposit is an important rare and precious metal production area in the Kerkbet mining area. Partial exploration work has been carried out in this area to further support the development of mining resources. Through geological surveys and geophysical and chemical analyses, the geological characteristics and prospecting indicators of the area have been clarified. Research has shown that the Mier deposit is controlled by the main fault F12, and its main mineral deposits are located in the ore controlling structural fracture zones of F12-1, F12-2, and F12-3. The overall orientation of the ore body is around 85 °∠ 75 °, with a depth of over 350m. The host rock is mainly quartz sericite schist, and the mineralization related changes mainly include limonitization alteration zones, weathering alteration leaching limonitization red soil layers, magnetite mineralization, pyrite mineralization, brass mineralization, etc. The mineralized zone of the ore body has obvious induced polarization characteristics, and the VTEM (airborne electromagnetic method) and remote sensing analysis methods can be used to determine the ore bearing range and depth direction. The degree of metal element enrichment can also be determined through chemical methods, clarifying the target area for mineral exploration and providing specific directions and scientific guidance for the next exploration work.