CHINA MINE ENGINEERING

Abstract:A mathematical model is established for the stress and seepage of a coal mine underground reservoir dam based on coupled hydraulic equations and basic equations of elasticity. The model is imported into COMSOL Multiphysics to analyze the evolution rules of water seepage height and safety factor of the dam as the change of water depth in the reservoir, and study the effect of different water depth on the stability of the dam. The results show that as the increase of water depth, the water seepage height is raised and the safety factor is decreased, which is unfavorable for the stability of the dam.

Abstract:This paper is based on a large limestone mine construction project in Hebei Province. In order to study the excavation stability and reinforcement measure of the mine slope, FLAC (a 3D digital simulation software) is used for modeling and calculation of the mining slope, with the expectation to provide some practical value and guidance for actual mining projects. The study results show that under normal working conditions, as the excavation of benches, more and more obvious displacement occurs to the slope rockmass, which brings more and more safety risks to the mine construction. The poor stability of soft rock strata directly influences the firmness and stability of the mine slope and makes it easy to occur curved landslides, further leading to the buckling failure of rockmass. To strengthen the slope protection and safety, anti-slide piles are used for reinforcement. This measure has played a good effect in controlling the plastic zone of the slope and reducing the increasing displacement and shear stress of the slope. Meanwhile, the safety of rockmass has been improved and the stability of rockmass has been further enhanced.

Abstract:Torque models are established for wire ropes of different structural characteristics, based on which a torque formula is proposed and used to calculate the torque of the wire rope of a specific structure. According to the calculation results, a general solution of wire rope torsion coefficient is fitted out. Moreover, the effect of wire rope structure and lay angle on the torsion coefficient and the effect of the torsion coefficient on the safety clearance between hoisting containers are analyzed. Finally, opinions are put forward on the production and selection of wire ropes for reference and discussion by relevant practitioners.

Abstract:Distortion of wall rocks during tunnel excavation is a key factor influencing the stability of tunnel structure and the safety in tunnel construction and use. Against this background, a triaxial compression test and FLAC3D-based numerical modeling are carried out to analyze the strain and failure characteristics of natural sandstones under different inner diameters and different unloading states. By comparison of the distortion properties of the specimens in the two tests, the following conclusions are drawn: under the same test condition, the tangential strain of the specimens increases with their size; the strain value under transient unloading condition is larger than that under slow unloading condition; the unloading effect under slow unloading condition is more sufficient; the tangential strain value obtained in the numerical modeling is smaller than that from the triaxial compression test, but the variation trend of the strain value in the two tests is basically the same.

Abstract:Engineering disasters may occur in the deep mining of mines, such as great distortion of wall rocks, rockburst, etc. In this paper, rock mechanical tests are carried out to analyze the brittle-ductile and rheological properties of the representative ore mined at the great depth of a mine. Meanwhile, reasonable suggestions are proposed on the control of wall rock distortion during deep mining.

Abstract:With the increase of mining depth and the improvement of advancing technology in the Jinchuan Mine, the traditional leveling and trigonometric leveling methods can no longer meet the requirements of mining production. In order to solve the above problem, the principle of the total station trigonometric leveling using midway method is analyzed in this paper and the error propagation formula of the intermediate trigonometric leveling is deduced and verified against the engineering realities in the Jinchuan Mine area. The results show that the accuracy of the total station trigonometric leveling using midway method can meet the Class II leveling accuracy in the Jinchuan Mine, even Class I accuracy of the mine to a certain extent. With the continuous improvement of the measuring instrument accuracy, this method will also be widely applied in future mining engineering works.

Abstract:According to the strength test results, the grey correlation analysis method of grey system theory is used to analyze relationship of various factors affecting the strength of backfill, it provides a simple and effective method for sensitivity analysis of factors affecting the strength of backfill. The results show that the lime-sand ratio is the primary factor affecting the strength of backfill. According to different strength requirements of backfilling, the mine can select the appropriate lime-sand ratio to save the backfilling cost.

Abstract:This paper contains an analysis on the main reasons for the changes of hydrogeological conditions and the short-term surge of underground water inflow caused by the combination of open-pit and underground mining in a copper mine in Jiangxi Province. On this basis, the water inflow and drainage capacity are re-verified and targeted water control measures are put forward, which can provide a good reference for water prevention and control works for open-pit and underground combined mines in rainy areas at home and abroad.

Abstract:In this paper, multi-group tests on the monominerals and artificial mixture of pyrite and arsenopyrite are conducted. The results show that y-As can effectively inhibit arsenopyrite in a suitable pH range, greatly reducing the floatability of arsenopyrite and effectively realizing the separation of sulfur and arsenic. The inhibition mechanism of y-As is preliminarily proved by analyzing the infrared spectra of the inhibitor and the Zeta potential change of the minerals before and after the action of the inhibitor. It's also found in the application of y-As in industrial production that it has an obvious inhibitory effect on arsenopyrite minerals.

Abstract:In order to reduce the gas emission in mined-out areas during 12408 working face stoping of Tunlan Mine, the surface L-shaped drilling is applied to gas extraction. Numerical simulation and theoretical calculation methods are used to determine the layout of the drills, the structure parameters of the drill holes are selected according to the site geological conditions, and the L-shaped drill hole gas extraction effect is analyzed in details. After site application, the gas concentration in upper corner and return air shaft of 12408 working face is reduced to less than 0.32% and 0.25% respectively, and the purpose of reducing gas emission in the mined-out area is achieved.

Abstract:In order to ensure the slope stability in the fissure area of Heishantou open-pit coal mine, by combining the geological conditions of the open-pit slope and the development characteristics of the fissure area, FLAC^3D+SLIDE numerical simulation is used to evaluate and analyze the slope stability in the area. From the analysis results it can be seen that there is a sliding trend in the fissure area in the northeast corner, and the slope is unstable. Therefore, corresponding measures are needed for slope control. Based on the current slope control technology, slope foundation clearing is selected and the control effect is evaluated and analyzed. The results show that after the slope clearing measures are adopted in the fissure area, there is no slope sliding in the area and no such tendency in the follow-up mining of the pit, which ensures the slope stability in the fissure area of the pit.

Abstract:The roof of 183_down 03 belt conveyor roadway is mudstone which can be easily broken under the influence of mining. In order to improve the strength of roadway support, the parameters of original bolt-mesh-cable support need to be optimized. Five support schemes are designed by using different anchor bolt density and anchor cable length. According to the stress and displacement changes of roadway wall rock in five support schemes simulated by FLAC^3D the results show that the roof deformation is smaller as the density of anchor bolt becomes higher and vice versa. The most reasonable parameters of bolt-mesh-cable support are determined in combination with economic benefits of mine. By monitoring roof deformation, it can be seen that the support strength is improved significantly after parameter optimization, and the roadway safety can be guaranteed under dynamic pressure.

Abstract:The 6309 track roadway in Tangkou Mine is adjacent to 6308 goaf, and excessive gas and spontaneous combustion of residual coal in the goaf are highly likely to take place during construction of the track roadway. In order to ensure the operators' safety and prevent spontaneous combustion of residual coal in goaf, the spontaneous combustion risk analysis is carried out and the nitrogen injection technology for fire prevention and control is simulated. The gas in 6308 goaf is displaced by nitrogen injected from high-level boreholes in 6309 track roadway and the goaf temperature is reduced so as to prevent spontaneous combustion of residual coal in the goaf. The results show that the CO concentration, gas concentration and CO₂ concentration in the upper corner decrease by 78%, 76% and 100% respectively after implementing the nitrogen injection technology.

Abstract:One copper mine in Shanxi Province is used as an example, where chalcocite and associated minerals of pyrite are main components and can't be separated by traditional xanthate flotation method. Therefore, electrochemical separation is adopted, and the Tafel curve is used to analyze the change in crystal structure of copper powder during separation. The optimum temperature and pH value for separation are obtained from tests with a single variable, and the potentiostatic test is used to find out the reaction mechanism of electrochemical separation for copper mine, so as to provide the first-hand information for production in the future.

Abstract:In order to promote the effect of coal seam gas drainage, the surface fracturing method is adopted by Tunlan Mine to improve the coal seam gas permeability, and parameters of surface fracturing boreholes and coal seam permeability enhancement are set up. After surface fracturing is applied on site, the 2# fracturing area presents an oval shape with surface fracturing well in the center and two axes of 100m and 40m; after fracturing, the coal seam permeability coefficient, gas drainage concentration and purity have increased by 227.2%, 170% and 158% respectively, which indicates that the surface fracturing improves the gas drainage effect significantly.

Abstract:Taking advantage of incompressibility and dust-suppression properties of water, the hydraulic blasting technology has attracted attention of the blasting industry since it was used. In view of the difficulty in mastering the application points and its unsatisfactory effect, the technology has not been applied widely. After technical modification, this technology is put into several practices of limestone for cement, and a hydraulic blasting technology scheme suitable for the mine is developed. It serves as a reference for cost reduction, ore fragment size balance and dust suppression of mine blasting in the same industry.

Abstract:To improve efficiency and reduce energy consumption of belt conveyor, an intelligent speed control system of belt conveyor based on computer vision technology is put forth and applied to belt conveyors in the 1506 main roadway. The results show that: (1) applying the computer vision technology to coal flow monitoring of conveyor has such advantages as convenient arrangement of monitoring points and highly reliable monitoring results. Besides, this can provide certain basis for the subsequent unattended belt conveyor in the mine. (2) Applying fuzzy control to the intelligent tiered speed control of belt conveyor and formulating reasonable ranges of coal flow and conveying speed based on changes in coal amount, which not only meets the needs of coal conveyance in the working face, but also avoids issues such as a high failure rate of motors as a result of frequent speed control of conveyors. After adopted by the site of 1506 main roadway, this intelligent tiered speed control system can control the speed of belt conveyor at 3.5m/s for a long time, and make intelligent adjustments to the speed based on changes in coal amount, which not only satisfies the need of coal conveyance but also remarkably reduces energy consumption of conveyor.

Abstract:As an indispensable building in mine engineering, the screening plant serves as the place to screen, sort and transport received materials. The reciprocating movement of vibrating screen in the plant can result in vertical vibration of plant roof and overall horizontal vibration. The structural layout of screening plant is largely influenced by the process layout. The opening area in floor slabs is large, the layout of columns is restricted, and the structure is complex. Many factors can affect the anti-vibration ability. This paper uses design cases to conduct a trade-off study on the framework of screening plant and a finite element analysis of the overall framework and partial floors so as to provide the basis for addressing the vibration issue of screening plant.

Abstract:To reduce the impact of spontaneous combustion of coal seam on stoping of working faces, with stoping of the 3102 working face as the background and according to production characteristics of working faces, this paper formulates fire prevention schemes for working faces during normal stoping and fault crossing, narrow coal pillars and adjacent mined-out areas in order to fulfill targeted prevention and control of spontaneous combustion of coal seam and ensure safety during working face stoping. The study serves as a reference for fire prevention work during mining of other similar coal seams inclined to spontaneous combustion.

Abstract:With a surge in the demand of metal resources, the exploitation range of large-scale open-pit mines gradually expands and the impact on their slope stability by adverse geological process is increasingly severe, which greatly increases the possibility of geological hazards in the mining area and restricts safe and efficient mining. In light of this, this paper conducts an in-depth analysis of adverse geological process that influences slope stability. Comprehensive analysis is carried out on key factors of adverse geological process that affect slope stability, including fault activation, earthquake and complex mined-out area. Based on these obtained factors, targeted precautions are put forward, including slope cutting, foot backfilling and anchorage reinforcing, which can provide effective solutions and a reliable guarantee of safe and efficient production for mines with similar geological conditions.

Abstract:To enhance the reliability and efficiency of safe production monitoring system of mines, a safety monitoring system is designed based on CAN bus, and its composition, hardware and software are all designed in detail. This designed monitoring system can monitor the composition of harmful gas and operation of mechanical and electrical equipment underground, and has the function of automatic alarm. When monitoring results are abnormal, underground intelligent nodes and surface monitoring center will automatically send out early warning information, improving the safety guarantee capability of mines to a certain degree.