Advanced Materials Research Vols. 524-527

Abstract: Suffering from the effect of the high ground pressure, water spraying from roof surrounding rock or geological tactics such as faults or collapse columns, roadways used to have large deformation, even lead to caving accidents. Based on the supporting research of the above complex conditions, the supporting background of a typical roadway No.202 affected by high stress, water spraying and large faults is analyzed and the corresponding technology is put forward. In addition, the support experimental test is conducted on the roadway, and the observation results show that the convergence of both sides is controlled well, and abscission layer is little.

Abstract: Coalbed methane (CBM) is a clean energy, especially the grim situation of the current international rapid economic development, the growing shortage of energy, environmental pollution and mine safety, making the production of CBM effective rational exploitation became more urgent important. This article describes the current technology of CBM exploitation, and comments the advantages and disadvantages of the main CBM exploitation methods. And it is also introducing several new techniques and the most development potential of the CBM exploitation method. It will provide a useful reference for the sustainable development of China's CBM exploitation.

Abstract: In order to improve the heading speed of the seam gateway and mitigate the problem of mining maladjustment in high-gas mines and coal and gas outburst mines which are almost low permeability, highly-gas content and it is difficult to eliminate the gas-outburst dangerous by the conventional pre-drainage technologies in a short period. The paper puts forward the view of strip gas pre-drainage with boreholes along coal seam from front traverse of the rock roadway over the seam roof, which can greatly save the time of gas pre-drainage to eliminate gas outburst dangerous by drilling and gas pre-drainage simultaneously for the trips between two traverses. The test results showed that the ratio of roadway driving to gas pre-drainage were increased from 0.31 to 3.6,the speed of driving increased from 50m to 105m per month and the time of roadway drilling and blasting heading per hundred meters from78 days reduced to 19 days. So this technology can greatly mitigate the replacement contradiction of mining and roadway driving.

Abstract: An experiment extracting CBM with surface borehole from mining subsidence area of a 6.25 meters thick coal-bed workface was done in Jincheng city. The test borehole was designed three stages based on the geologic structure of test field. During underground workface passed through borehole, the operational status of well was recorded and the deformation of casing was detected four times. Test has shown that the highest pure flow of surface borehole can reach 8m3/min which proves that the methane extraction technology with surface borehole from mining infection zone has a bright future for application in Jincheng city. But, how to maintain the stability of casing avoiding damage is still a problem, which should be resolved before the drawing technology is used in Jincheng extensively. Besides, the ordinary protecting skills for borehole used in oil exploitation cannot take a satisfactory effect to protect tube against damaging due to overburden rock movement during mining. The casing will be damaged at several positions, especially near the junction of soft and hard strata. It may be right measure to expend the diameter of tube or install special defensive joints at the places where will deform badly under the mining influence.

Abstract: Large number of valuable Uranium resources has been transformed to remnant ore, due to mining conditions of the deposit can not be recycled in the process of development and utilization. Such as reservation pillar in conventional mining, low-grade and residual ore bodies, remote and lonely ore bodies and so on. In order to exploratory research relevant technical problems of remnant Uranium ore resources recycled by stope leaching technique, experimental study were carried out in a Uranium mine. According to the remnant ore body occurrence conditions and make full use of the original sinking and driving engineering, adopting special stacking by blasting methods and reasonable lixiviant distribution and lixivium collecting technology, the remnant uranium ore resources recycling technology problems were solved by a small project investment. After 10 months of solution leaching, leaching of metal 5.18t, leaching rate up to 65.57%, the tons of metal cost for its existing mining cost 2 / 3.The stope leaching technology in remnant ore resource recycling is more perfect, expand the scope of application of the technology.

Abstract: The application of UDEC software helps to simulate the changing regularity of the front and posterior abutment pressure and the pressure in the goaf within the scope of propulsive distance 220m in the coal face. Incorporating the Origin software the simulation analyzed the changes and correlation of the three kinds of pressure. We can see that when the propulsive distance is within 60m the change of the front and pressure is the same to the change of the back abutment and with the increasing of the pressure the posterior abutment pressure reaches its peak first. When the propulsive distance exceeds 60m the pressure of caving gangue in the goaf begins to increase and share some of abutment pressure. Each time the main roof collapses the concentration factor and the location of the peak of the front abutment pressure will fluctuate. The concentration factor fluctuates between 2.04~2.41 and the location of peak fluctuate between 7m to 10m. With the propulsive distance increasing, the posterior abutment pressure will tend towards stability when the propulsive distance is 140 m. The goaf which experiences the change trend of low pressure -high pressure -reducing to raw rock pressure has three areas: depressor area, pressurization area and stability area. The stress depressor area which is in the range of 10 to 20 m exists every 20 to 30m in the cut-hole and the gangue compacting area.

Abstract: The gas-pulverized coal two phase flow law of gas is simulated by the use of the theory of jet after coal and gas outburst. Research results show that as the volume fraction of pulverized coal in outbursts mixture increases, the speed of two phase flow at the exit gradually reduces, jet core length shorter, turbulent longitudinal effect range smaller, jet width narrower. And dynamic head mainly concentrates in the jet core area and its distribution is more uniform in the roadways. The maximum speed of outburst two-phase flow decreases with the adding volume fraction of pulverized coal, that is higher the coal content in outburst mixtures, smaller the maximum speed after outburst. But a high content of coal have higher impact strike force which can cause major damage effect. The research may provide some theoretical basis for setting underground safety facilities, mine personal protection, disaster warning and emergency rescue.

Abstract: The rate of gas drainage is lower in mining faces of low permeability of extra-thick seam, and with lots of gas emission, which brings greater security risks. Through the Pre-pumping experiment of deep hole pre-split blasting for 216 mechanized mining face in Xiashijie coal mine of TongChuan coal group, increased the rate of gas drainage over 17% in working surface, that reduced potential safety problems during production, and indicated the direction for later gas government.

Abstract: 40110 working face is located in CaiZiYuan Chengguan town of Binxian county.It is arranged as the third mechanized mining caving working face. According to the geological characteristic in the area, it was researchd on the roof and floor lithologic, structure, hydrology, gas, dust features and so on, and devised mining tunnel supporting about tunnels , section , horizon , support instructions by experience, calculating, analysis. Practical result shows that the two sides displacement and relative movement of the roof and floor effectively controled to ensure the daily production of coal mine by the tunnel supporting design.

Abstract: With mining depth and state-wide expansion in open pit mining, it is necessary to bulid a three-dimensional visual model of open pit mining boundary, which can be used in the analysis of pit slope stability, engineering decisions, geological analysis and production planning. In this paper, a three-dimensionla visual model reflecting the complex formation load and terrain conditions was built by collecting original open pit design and geological data. With this model, stability analysis of open pit can be obtained and theoretical basis for selection of design can be provided. In the specific prcess of modelling, the original information in the existing CAD mining topographic maps were be used fully and the mine topographic maps was imported into Surpac mining software. Surface digital terrain model can be obtained elevation assignmented by corrction processing of CAD linears and vector processing of measring point data. On this basis, by using MIDAS software and considering the requirements of the scope of computational space, a three-dimensional model can be obtained through Boolean cut operations. With this model, the real surface shape of open pit mining boundary can be reflected.