CHINA MINE ENGINEERING

Abstract:In order to study the law of oxygen concentration distribution in the goaf of the coal mine working face, identify the risk of spontaneous combustion in the goaf and the risk area of spontaneous combustion, the buried thermocouple sensor and sampling bundle tube are used to summarize and analyze the monitoring temperature changes and gas content changes caused by the increase of the buried depth of the goaf, and the relationship between the CH₄ and C₂H₆ gas originally stored in the goaf coal of the working face is studied by establishing a mathematical equation, and it is concluded that the exponential function has the highest fitting degree, 0.9527. The change rule of O₂ concentration at different positions in the goaf is obtained by using the sampling bundle tube, and the physical model is established with Fluent according to the actual situation. The boundary conditions of the model are analyzed and set, and it is concluded that the oxygen concentration gradually decreases and the degree of decline gradually decreases with the increase of burial depth. Through the field test and laboratory data simulation of the oxygen concentration zone in the goaf of the coal mine working face, the fan-shaped areas of the “three zones” (heat dissipation zone, oxidation zone and suffocation zone) at different positions in the goaf are obtained, which provides guidance for the fire prevention work.

Abstract:Pulang Copper mine is mined by natural caving method. Under the influence of three fault zones interweaving, the bottom structure of Pulang copper mine is deformed and destroyed. The exploration data show that the surrounding rock of the excavation roadway under the fault has been damaged, and the failure location is generally 2.5m and 8m on the roadway surface. It can be known by numerical simulation that the stress concentration of roadway occurs at the intersection of fault and roadway, which is also the main area of deformation and failure. According to the characteristics of stress concentration and roadway failure, the single-layer spray anchor net support is adopted for mine gathering tunnel, the double-layer spray anchor net + long anchor cable support is adopted for mine exit approach, and steel arch support is added at the eyebrow line position. The support test is carried out at the corresponding fault location of pull-down perforating vein, and certain results are obtained. The method has remarkable effect on ground pressure control, and the research results can provide reference for similar mines.

Abstract:In order to ensure that the stability of sublevel open stoping with subsequent backfilling of Sareke copper mine，and to determine the suitable stope structure and the filling process parameters, based on uniform design method, experiments respectively using FLAC3D to simulate the filling height, at the bottom of the mine roof water cement ratio at the bottom of the top strength and middle tier intensity of water-cement ratio, and the effects of three factors in mining. The measured displacement of roof, floor and roof and floor filling height, roof and floor, water cement ratio, intermediate water cement ratio relation between the filling layer. The results showed that the roof and floor filling height, the greater the water cement ratio, the greater the roof displacement is smaller, the filling effect is better. Recommended mining using contrast filling material for 1∶6 for stope filling,later can effectively control the stope wall rock deformation, to ensure the stope stability.

Abstract:Natural caving mining method as a low-cost and large-scale mining method, ore rock in the self-weight stress and structural stress under the action of natural caving, and through the output level of the polyore trough release, ore continuous transportation, the surface gradually collapsed to form an open pit, with the continuation of mining activities, the surface collapse pit will become larger and larger, when the rainfall increases, the surface rock in the collapse pit is broken for the formation of debris flow to provide a rich source of solid matter, continuous release impact for debris flow to provide channels and inducing factors, Continuous release is easy to cause underground debris flows. Taking the copper mine as the engineering background, through the occurrence of underground debris flow since 2019, the main factors controlling underground debris flow are determined from the analysis of the source conditions, topography and geomorphology and inducing factors that trigger the underground debris flow, and the research results show that the occurrence of underground debris flow is inseparable from the three elements of material source conditions, topography and geomorphology, and inducing factors, and the treatment of underground debris flow requires changing the surface collapse pit, controlling water sources and material source collection, and controlling ore release for comprehensive treatment.

Abstract:In order to realize the quantitative prediction of nonmetallic mineral resources in the open air, a three-dimensional quantitative prediction model of nonmetallic mineral resources is established by combining theoretical analysis with big data mining algorithm on the basis of computer technology under the guidance of geological theory. Collect geological data, simulate resource distribution state through binomial distribution model, count the expected number of ore spots and corresponding function relationship, extract data characteristics, complete data association analysis, build spatial attribute database, process data by amplitude adjustment, eliminate information error, reduce data loss, train sample data to calculate the prior probability of quantitative prediction model, and obtain ore control factors and importance evaluation indicators, The final quantitative prediction results are obtained. The experiment part proves that the proposed model has high prediction accuracy, and the 3D visualization results can clearly show the location of mineral resources, which is of high application value.

Abstract:The SICOMINES copper cobalt mine in Congo (Kinshasa) was selected as research background. Through analyzing the hydrogeological conditions of the mining area, the evolution characteristics of groundwater flow field and drainage datafrom 1976 to 2022, the law of water level variety were studied in depth. The results indicate that the dynamic variation characteristics of groundwater were mainly dominated by lateral recharge, followed by precipitation, and Drainage is mainly dominated by supply, followed by storage. The groundwater flow is dominated by pipeline flow and supplemented by seepage,close connection between aquifers, low groundwater seepage resistance, gentle slope, good connectivity, and the drainage of the lower aquifer can reduce the water level of different aquifers. The groundwater system is mainly composed of fractures and caves, and the main groundwater runoff zone is collected by cavities，groundwater is controlled by geological structure.

Abstract:In a fluorite mine in Xinjiang, the main content is fluorite and calcite (32.90% and 53.63%, respectively), followed by quartz (7.43%). Some of the fluorite minerals in the ore have coarse grain size, and some of the fluorite forms veins and vein-like structure. At the same time, some fluorite metasomatism other minerals, which is difficult to dissociate. Beneficiation test research was carried out according to the ore properties. The test showed that when the grinding fineness of -0.074mm was 70%, the flotation process of “one coarse-six concentrate-one sweep” was adopted, acidized sodium silicate and AB-123C were used as inhibitors, the dosage of the two inhibitors were 600g/t and 300g/t, and AB-CD was used as collector, the dosage of which was 450g/t. A fluorite concentrate with a concentrate rate of 26.69%, a CaF₂ grade of 97.21% (FC-97A quality), a CaF₂ recovery of 83.13% and a CaF₂ grade of 0.55% was obtained.

Abstract:In order to improve the effect of gas drainage in low permeability coal seams, the pressure relief and permeability enhancement effect of low permeability coal seams was studied by using the hydraulic large-diameter graded hole making technology. Through the stress balance equation, gas seepage equation and coupling equation of coal, the process of gas adsorption, desorption, seepage and the coupling relationship with stress in coal are analyzed. By using COMSOL Multiphysics software, a three-dimensional calculation model of pumping and hole making with zero permeability boundary is constructed, and the pressure relief pumping effect under different pumping time and different hole making radius (0.3m, 0.6m, 0.9m) is studied. The research shows that the gas pressure around the borehole decreases with the continuous gas drainage after the coal seam cave is built. With the gradual increase of the drainage time, the gas pressure reduction area expands gradually, and the pressure relief range increases continuously. The gas pressure drop speed of the hole cavity model with a radius of 0.9m is more obvious, which can relieve the pressure and increase the permeability of the coal seam in a shorter time to achieve the coal seam outburst elimination.

Abstract:Determining reasonable bedding drilling parameters is an important means to improve the efficiency of coal mine gas drainage.In the process of gas extraction, the matrix shrinkage and gas pressure changes caused by the deformation of the coal body are considered, and the COMSOL numerical simulation software was used. Two-hole and three-hole gas drainage effects under different drilling spacings, and gas drainage experiments were carried out in the 9306 roadway.The gas extraction effect under double hole arrangement shows two stages with the increase of drill hole spacing. The drill hole spacing is less than 3m, and the extraction time is short, and the extraction efficiency is high, but it decreases rapidly in the later stage. When the drill hole spacing is more than 3m, the extraction effect is lower than that of the drill hole spacing d=3m, and the gas extraction effect under three-hole arrangement is the best when the drill hole spacing d=3.5m.In addition, the area of the effective drainage area of each borehole is formulated. Through comparison, it is concluded that the gas drainage effect is the best when the three-hole arrangement and the spacing d=3.5m. The gas extraction test was carried out in 9306 roadway, and the difference between the test result and the simulated value was about 2.8%.The model has good applicability in the test mine, and can provide a certain theoretical basis for the design and optimization of drilling hole.

Abstract:In order to determine the optimal technical parameters of roof cutting and entry retaining with thick hard roof, the cutting heights of 5m, 10m and 15m and the cutting angles of 0°, 10°, 15° and 20° were selected. Through theoretical analysis and 3DEC numerical simulation, the shape of the roadway formed by the thick hard roof and the stability of the surrounding rock are studied. The results show that the roadway roof forms a “short arm beam” structure after roof cutting. When the roof cutting height and the roof cutting angle are constant, the greater the supporting force of the cut roof on the “short arm beam” of the roadway roof, the smaller the supporting force F required by the roof. Therefore, when cutting the roof into the roadway, try to make the cut roof fully connect to the roof; With the increase of the roof cutting height, the horizontal displacement value of the solid coal body side of the roadway increases and the vertical displacement decreases, while the horizontal displacement of the low roof of the roadway is almost zero; When the thick hard roof is cut into the roadway, it is necessary to maintain the inclined cutting seam. With the increase of the roof cutting angle, the vertical displacement of the roadway roof and the horizontal displacement of the solid coal body side increase. Based on this, the optimal roof cutting parameters with a roof cutting height of 10m and a roof cutting angle of 10° to 15° were comprehensively determined.

Abstract:In order to explore the deformation and instability characteristics of the surrounding rock in the large mining height mining roadway, through the 3DEC numerical simulation software, with the 22204 auxiliary transportation roadway as the background, the characteristics of cracks development, stress distribution, displacement distribution and plastic zone distribution in the surrounding rock of the roadway are analyzed respectively. Results show that the cracks development and deformation of surrounding rock in large mining height roadway are asymmetric. As the working face advances, the displacements of the roadway continue to increase. Among them, the larger horizontal displacement is transferred to the middle and upper part of the roadway and the roof position, and the horizontal displacement of the roadway near the coal pillar side and the development of cracks are more significant; Under the influence of mining, the surrounding rock of the roadway undergoes a certain degree of shear failure, which leads to the release of the stress of the coal and rock mass. In addition, the coal pillar is in a state of high stress for a long time, so the plastic failure of the roadway side and roadway roof near the coal pillar is more serious and frequent. Based on this, the key prevention and control areas for surrounding rock deformation of large mining height mining roadways are defined, which provides a reference for the stability control of such roadways.

Abstract:Pebble is one of the key factors affecting the processing capacity of SAG mill. In order to break through the bottleneck of a multi-metal concentrator in Yunnan Province, this paper carried out a targeted study on the SAG mill pebble, carried out the property study of pebble, the open-closed circuit test study of pebble and the simulation analysis study of JKSimMet software, and analyzed the influence of different treatment methods on the system productivity of pebble. The research shows that the processing capacity of the SAG system can reach 400t/h under the condition of direct closed return of pebble, and the processing capacity of the SAG system is expected to reach 425t/h under the condition of closed return of pebble crushing, It provides scientific basis for the capacity upgrading scale and technical transformation scheme of concentrator.

Abstract:After Donghuantuo Coal Mine is extended to the -950 level, the gas content and pressure in the coal seam gradually increase, and the risk of gas disaster is high. In order to solve the safety problem of coal uncovering in the new horizontal crosscut, we independently designed and developed a compensated non pressure relief device for upward gas pressure test boreholes and a secondary plugging process of high-pressure grouting, innovatively solved the problems of hole sealing and confined water interference encountered in the pressure measurement process, rationally designed a comprehensive gas control program, and completed the coal uncovering in the new horizontal crosscut safely and efficiently. It has laid a solid theoretical and practical foundation for the subsequent coal seam uncovering and gas control in other coal seams.

Abstract:Based on the investigation and study of uranium mineralization display, ore-controlling factors and uranium mineralization mechanism in Jierastai volcanic fault basin, it is believed that the basin has superior uranium mineralization geological conditions, strong tectonic magmatism, and the main uranium-rich rock series are the acidic and acidic volcanic rocks in the Upper Jurassic Manketou ebo Formation and Baiyingaolao Formation, with well-developed tectonic fractures and strong hydrothermal alteration. The basin is a favorable prospective basin for searching for volcanic-type uranium deposits, In the basin, the composite part of volcanic mechanism and fault, the part with obvious difference in alteration development and rock physical and chemical characteristics are the key uranium prospecting parts.