CHINA MINE ENGINEERING

Abstract:In order to investigate the influence of freeze-thaw process on the temperature and mechanics of mine shaft wall under freezing construction conditions, the soil and shaft wall model was established by ABAQUS software, taking the lower reaches of Lalingoli River as an example. The characteristics of soil temperature distribution, wall Mises stress, and the evolution of vertical and thawing additional forces with temperature during freezing and thawing were analyzed by numerical simulation. The results show that the value of vertical additional force is stable below 0℃, and when the temperature exceeds 0℃, the vertical additional force decreases rapidly along with the melt settling process. In the process of 0~5℃, the additional force of melt settling increases rapidly, and when the temperature exceeds 15℃, the additional force of melt settling reaches a stable state. Under the influence of depth, the stress of borehole wall is mainly controlled by ground stress. With the gradual increase of formation depth, the maximum value of the additional force shows an exponential trend.

Abstract:Gushan iron ore mine selects upward horizontal stratified filling mining method and upward approach filling mining method to mine under different geological conditions, in order to optimize the structure of the quarry, this study proposes 3-4 kinds of quarry parameter schemes by means of theoretical analysis and engineering analogies, and then according to numerical simulation means, selects the suitable quarry scheme from the aspects of quarry safety, productivity and production arrangement, optimizes the layout, and provides design references for mine provide design reference for safe and efficient mining and reduce loss depletion.

Abstract:It is difficult to control the creep deformation of high stress poor roadway in a copper mine and high maintenance cost. In order to reduce the cost of roadway support, this paper analyzes the deformation and failure characteristics of deep surrounding rock and the main influencing factors. Aiming at the problems of large deformation and high maintenance cost of shotcrete anchor+U shaped steel frame+anchor grouting (SUG) combined support, the combined support technology of shotcrete anchor+steel tube beam support+anchor grouting (SSG) is studied. Then, on the basis of determining the two supporting parameters, FLAC finite difference analysis software is used to carry out the numerical simulation of surrounding rock of SUG and SSG supporting roadway. The results show that the maximum deformation of SUG and SSG support rocks is 38.6mm and 25.7mm respectively, and the maximum deformation of latter is 33% lower than that of the former. Under the same conditions, the costs of SUG and SSG support and repair within two years of 50m roadway are 1.55 million yuan and 0.8 million yuan respectively, and the latter is 48% lower than the former. At last, the site test of SSG support was carried out in the bad strata in the 1000m middle section of mining area, and the deformation monitoring of supporting roadway is carried out for 3-5 years. The results show that SSG support roadway has good stability, strong security and high cost performance, which meets the requirements of creep deformation control of roadway in high stress poor strata, and has been popularized and applied in the construction of deep bad strata roadway in the copper mine.

Abstract:Aiming at the severe challenges facing the informationization construction of safety production in Chinas open-pit mines, such as the prevalence of information silos, the difficulty of integrating multisource sensor data and the imperfect early warning mechanism of safety hazards in mine operations, put forward the concept of a smart mine safety production management platform with multisource data fusion technology, and based on this, we carry out a technological analysis of the smart mine safety production management system, which is made from the sensing layer, the data layer, service layer, Application Layer and Presentation Layer 5 levels to explore the overall framework design of the intelligent mine safety production management system, and developed functional modules containing user management module, data monitoring module, twin base module, data analysis module, alarm module, scene management module, data management module, visualization module and so on. Accessing the data of Ordos Tengyuan Coal Co., Ltd. mine, the smart mine safety production management system constructed realizes comprehensive perception, accurate simulation and scientific prediction of mine operation status, significantly improves the operation efficiency and safety of the mine, enhances the competitiveness of the mining enterprise, and realizes the sustainable development of great significance.

Abstract:Aiming at the mutual disturbance problem between 10205 working face and its lower 20203 working face during the downward mining process of close coal seam in Longhua coal mine. Theoretical analysis, FLAC3D numerical simulation and other methods were used to study the characteristics of the stress distribution in the mining field of the 10205 working face, the distribution law, the depth of the bottom plate damage, and the support parameters of the 20203 roadway, etc., and to investigate the influence of the 10205 working face in the 1-2 seam on the stability of the construction of the 20203 roadway of the 20203 working face in the 2-2 seam during the process of the mining back. The results show that, at the initial stage of 20203 roadway excavation in the lower coal seam, the roadway is only affected by the stress perturbation brought by its own excavation, and the roadway peripheral rock stress shows a uniform and stable change as a whole. When the length of the upper seam working face is 325m, the maximum damage depth of the upper seam working face bottom plate is 20m. The peripheral rock stress of the lower seam back-mining roadway does not change much compared with the period of digging, and the back-mining roadway is kept stable in the process of mining the upper seam. At the same time, the main stresses in 10205 working face are transmitted to the bottom plate in a diffuse manner, the largest main stress diffusion area is in the stress increase area, while the smallest main stress diffusion area is in the stress decrease area, and both of them are similar in the distribution law, and the stress concentration occurs in the stress increase area. According to the theoretical model of slip line, the maximum damage depth of the upper seam bottom plate is 18.6m, which is close to the numerical simulation results. The results of the study are helpful to ensure the safety of the downstream mining of the close coal seam and the stability of the support of the roadway in back mining.

Abstract:Protective layer mining is an effective technical measure to prevent and control rock burst of coal seam groups. In order to explore the relief effect of protective layer under different mining parameters, the influences of mining height, layer spacing and working face length on vertical stress distribution and floor relief degree of protected coal seam were systematically analyzed, and quantified by calculating the relief coefficient. The results show that the increase of mining height and the decrease of layer spacing will lead to the improvement of pressure relief effect. The pressure relief of the protective layer decreases gradually with the increase of the length of the working face, and the pressure relief range increases with the increase of the length of the working face. The analysis of the pressure relief degree of the floor shows that the increase of mining height and working face length is conducive to improving the pressure relief effect of the floor. When the layer spacing is less than 20m, the critical depth of floor pressure relief gradually increases, while when the layer spacing is greater than 20m, the critical depth of floor pressure relief gradually decreases and gradually reaches stability.

Abstract:After the formation of a coal face, there will inevitably be some differences between the exposed faults in roadways and the interpretation result of the 3D seismic data. It is necessary to re-predict faults in the face before mining. The seismic data contains much useful information that has not been discovered. If the exposure of faults can be combined with the 3D seismic data to re-predicte faults. It will effectively improve the accuracy and applicability of the re-prediction results. The volumetric curvature provides a simple method for re-predicting faults in coal faces. The calculation parameters are determined based on the occurrence of the exposed faults, and the volumetric curvature attributes are generated from the stacked seismic section. The slice along the coal seam of the attribute body can effectively reflect the shape of the target fault. The validation was conducted using 3D seismic data and faults measurement data from the two roadways of the Renjiazhuang 110905 coal face. The result showed that the wavelength parameters were obtained from the measured exposed faults. The volumetric curvature attributes generated from these parameters can better show the extension of the DF6, the DF12, and other associated faults in the 110905 coal face. It will provide a reliable basis for fault prediction and adjustment of mining plans.

Abstract:There are problems with insufficient support strength and unstable surrounding rock in the transportation roadway of the 15210 working face in a mine in northwest China. To address the issues with roadway support, high-strength prestressed anchoring technology is adopted for treatment. Numerical simulation was used to study and analyze the strain of surrounding rock after the implementation of ordinary anchor rod and high-strength prestressed anchor rod support technology. The research results showed that the high-strength prestressed anchor rod support technology can control the strain of surrounding rock within 60mm, and the support effect is good. To ensure the safety and reliability of the roadway support structure, a combination of anchor rod and anchor cable support and U-shaped steel reinforcement support are proposed. After the support is completed, the displacement of the roof and two sides in the support area is investigated. The investigation results show that the maximum displacement of the roof after 120 days is 126mm, and the overall stability of the roadway.

Abstract:The research focuses on the inherent haracteristics of yrrhotite within magnetite-type copper ore and examines the unique eneficiation process applied for copper and iron recovery, comprising “semi-priority semi-mixed flotation for copper, regrinding of copper flotation tailings, magnetic separation for iron, and desulfurization flotation of iron concentrate.” It analyzes the fundamental reasons for the inhibition of pyrrhotite by lime. Through experimental investigations, an optimized reagent scheme for pyrrhotite flotation was developed. The experiments conclude that adjusting the flotation pulp to a pH of 5.2 with 2400g/t sulfuric acid and employing 200g/t copper sulfate as an activator for pyrrhotite effectively counteracts the inhibition by lime. By using B-45 as the collector and No. 2 oil as the frother, a five-stage open-circuit flotation yields a desulfurized iron concentrate with a sulfur grade of 0.23%, an iron grade of 65.34%, and an iron recovery rate of 83.22%.

Abstract:Based on the problems of old equipment, small type, large quantities, high maintenance costs, etc, technical transformation of SAG mill process was carried out on the pyrite mine in Guangdong. Simulation basic data was confirmed according to the research on ore properties and experiment results of crushing and grinding. One ?8.53m×4.27m SAG mill (5400kW) and one ? 5.8m×9.5m ball mill (5400kW) were selected according to JKSimMet simulation. Simulation on three different operation conditions demonstrated that different ore with different hardness and fineness could be treated, and the fineness of grinding products could meet design requirement. This study will provide technical support for the equipment calculation and future production adjustment.

Abstract:Taking a high arsenic and high sulfur copper zinc ore as the research object, a preferential flotation process is adopted to recover copper and zinc minerals from the ore. In the copper flotation stage, black catching agent No.25 is used as the collector of copper sulfide, calcium oxide and sodium humate are used as inhibitors of arsenopyrite, pyrite and sphalerite. In the zinc flotation stage, EF1108 was used as the collector for zinc sulfide minerals, and calcium oxide and sodium humate were used as inhibitors for arsenopyrite and pyrite, efficient recovery of copper and zinc minerals was achieved. In this study, the highly selective collector EF1108 was used as the collector of zinc sulfide minerals instead of the traditional xanthate agents, which played a high effect on the inhibition of arsenopyrite and pyrite at low alkalinity (pH 11.5).

Abstract:China’s non-coal mines are in the critical stage of digital transformation, as a high-intensity resource investment and labor-intensive enterprise, to solve the problems of mine brain drain, safety hazards, environmental negative effects, etc., relying on the deep integration of new technologies and mines, the construction of intelligent mines is the only way for mining enterprises to transform and upgrade, and the design-led EPC general contracting model as the current development trend of engineering general contracting can realize a more efficient connection between the stages of design, construction, procurement, installation and trial operation. Provide core support for the intelligent construction of mines.

Abstract:Both metal ions and slurry temperature have a negative impact on the floatability of fluorocarbon cerium ore, thereby affecting the grade and recovery rate of bastnaesite concentrate. Through the flotation test of bastnaesite pure mineral, the paper investigated the effects of different external environmental factors on the floatability of fluorocarbon cerium ore and regulatory control, with salicylhydroxamic acid as the collector. The experimental results showed that metal ionsand and slurry temperature have different degrees of inhibition on the flotation process of bastnaesite. The floatability of bastnaesite inhibited by metal ions and slurry temperature can be adjusted by adding lead nitrate as activator. Using lead nitrate as activator and mixing lead nitrate with salicylhydroxamic acid in advance can improve the floatability of bastnaesite inhibited by metal ions. The ratio of salic hydroxamic acid to lead nitrate was between 5∶(3~1), and the recovery rate of bastnaesite was more than 90%.

Abstract:In order to study the influencing factors of deep buried large section roadway floor heave and targeted comprehensive treatment measures, taking the 260303 track roadway as the engineering background, this paper conducts in-depth theoretical analysis of the influencing factors of deep buried large section roadway floor heave, and further proposes comprehensive treatment measures based on the analysis results. The results showed that the main reasons for the occurrence of floor bulges in track roadway 260303 were the complex geological stress environment, poor surrounding rock conditions, obvious rock hydration operations, and unreasonable original support forms, which resulted in multiple frequent occurrences of floor bulges in the roadway. Further comprehensive measures were proposed to change the shape of the original roadway, drill pressure relief holes, alternate long anchor cables and short anchor rods for joint support, and fully enclosed steel support with frictional sliding at the bottom. Through on-site monitoring, the deformation of the floor was reduced from 48mm to 15mm, meeting the production needs of the mine, greatly reducing repair and maintenance projects, and ensuring safe and efficient production of the mine.