Abstract: Aim at the problem of high gas content and low permeability at work face S1206, yuwu coal mine, pulsating hydraulic fracturing experiment was carried out to get a better effect on gas drainage. The principle of pulsating hydraulic fracturing is analyzed, fracturing borehole parameters, borehole sealing process and fracturing parameters are designed. Results indicate that for fracturing boreholes, concentration and flux of extraction gas are boosted by as much as 4.7 times and 6.3 times respectively compared with a normal borehole, for directional boreholes, concentration and flux of extraction gas are increased by 3.7 times and 3.9 times respectively. This technology provides a way of pressure relief and permeability promotion for coal seam.

the paper takes the East5# ramp soft rock of a coal mine in Shaanxi Tongchuan Mining Company’s as the research object, and uses similar material simulation methods to study failure characteristics and failure mechanism of soft rock roadway, the paper summed the process of roadway deformation and failure modes, through observation and analysis for appearance of the destruction morphological characteristics of the roadway; the paper summed the process of roadway surrounding rock deformation in the loading conditions through the monitoring of surrounding rock displacement；the paper summarized bolt anchor working condition through monitoring and analysis for bolt anchorage force. Finally，the paper summarizes characteristics of deformation and failure process of high-stress soft rock roadway with large section.

Shun he first coal mining face for the first oblique isometric tone design that will face cut position on the basis of the initial design to the head position as the center, clockwise 16 °, after tune after ramp may face increased 11575t mining resources; oblique after adjusting for the face, designed with a combination of the actual situation as long oblique tone recovery process, after calculation, transfer per cycle in accordance with the oblique head into a knife blade tail manner into five recovery. Engineering practice shows that the scheme not only improves the recovery rate, but also to solve the long-tune oblique face such challenges, the smooth realization without frame, without tank, do not brush the face of equal length to help tone oblique, research results face tone oblique design and stope mining with a reference value.

The issue of stress concentration in coal mine deep mining is particularly serious, with the engineering example of working-face 1305 in Tangkou Mine, ground stress distribution laws of one kilometer-deep large mining-height stope were numerical analyzed by using FLAC3D. Simulation results have revealed that: As mining starts in working-face 1305, a “double-lunds” shape symmetrical abutment pressure affected zone has formed in the surrounding rocks; as working-face promoting, the peak of stope abutment pressure and overlying strata failure height of goaf gradually increases, and the change tends to stability behind working-face square, the maximum peak is about 72MPa and stress concentration factor is 3.0; Abutment pressure peak value inside the coal in the front of working face coal wall and beside the gob area transfers to the deep, and the influence scope of abutment pressure gradually increases, the distance between the pressure peak value and the coal wall of working face basically keep in the range of 8 to 15 m.

Abstract: New ideas and concepts of the shaft structure design was introduced by analyzing characteristics of deep alluvium geological formation conditions, weathered bedrock and gushing water, etc of the deep alluvium of auxiliary shaft in the Xinhu mine. Under the new “code for design of concrete structures” requirements, limit state design method which was based on the probability theory was proposed to solve the problem of thick-walled cylinder structures under biaxial compression and triaxial compression, designed with a partial factor, and combining with specific factors engineering designing itself, the concrete of the relation between the enhanced coefficients are given. In the process of deep alluvium freezing wall design, there were important instructional significance for the well bore construction schedule, safety and economic efficiency.

This paper makes an optimization of stripping system of Donglutian Open-pit based on its mining conditions. According to the conditions of topography, geology, rock, coal seam and climate in the pit, this paper proposes several stripping plans for different levels including the upper layer of loess, rock layer above the No.4coal seam, rock layer between coal seams. And analyzes these plans qualitatively and quantitatively, determines the possible stripping methods for different levels. Based on the combination of these plans, a set of feasible plans for operations in Donglutian Open-pit is obtained. By analyzing economic indicators about the open pit mine, the combined semi-continuous system is selected for the mine at last , details as: the loose layer of peel is outsourced, 3 sets of self-moving crusher are used in 4th coal roof above 30m, and single bucket - truck intermittent process is used for the rest

Abstract: The stress distribution and the stability of the roadway surrounding rock is deferent from the typical gob-side entry driving when keeping small coal pillar to dig the lane along the gob-side entry retaining. It will benefit to the stability of the coal pillar and decrease the width of the coal pillar because of the high strength filling wall of the gob-side entry retaining works to support the roof of the goaf. In this paper numerical calculation software was used to research the stability of small coal pillar along the gob-side entry retaining and the effect on the deformation of the surrounding rock in driving tunnel with different width of coal pillar and different anchoring strength of rock bolts, a conclusion was drawn that the width of the coal pillar is the decisive factor which affects the stability of the coal pillar and the deformation of surrounding rock, and the high system support strength can control the deformation of surrounding rock efficiently. According to the engineering background of the 1111(1) working face’s track drift in ZhuJi coal mine, the vertical stress of the coal pillar is low with a small influence circle and the deformation of the coal pillar and the roadway, it’s stability is best of all when the coal pillar is 3m wide. The high strength bolt supporting scheme was determined based on that basis. The stability of coal pillar and the big driving tunnel deformation were successfully controlled.

Heat pump is a kind of system, which can shift a lot of can’t direct use of low temperature heat energy into a useful device of high temperature heat at the price of a small amount of electricity consumption. Combining with the different forms of waste heat recovery with heat pump system design, use heat pump unit to extract the mine ventilation, drainage, air heat and other waste heat for building heating or air conditioning, so as to replace the coal-fired boiler, is a new energy-saving, environmental protection technology, has important significance to the construction of modern green new mines.

Abstract: This paper introduces the principle of the half-bridge LLC resonant converter,and analyzes bridge LLC resonant converter dc gain curve. Combined with the current mine lithium iron phosphate,which requirements for high efficiency charger,we designe a high-power LLC lithium iron phosphate battery charger using the UCC25600 controller chip, and use PSIM for simulation. We made an experimental prototype: LLC Power Index is 25.2V/1000W, and it can charge six cells in series iron phosphate lithium battery packs. Experimental results show that LLC mine lithium iron phosphate battery charger has high efficiency, stable output voltage.

Mine explosion-proof cover for the existence of traditional air leakage, reposition difficult, inconvenient operation and maintenance and other issues, designed the explosion-proof cover structure in an innovative way, analyzed intensity and stress of each part during normal operation and explostion with the help of The finite element analysis software ,it can ensure the safety of the mine explosion-proof cover, and improve the reliability of the ventilation system.

The paper introduced a design of the rockburst monitoring and warning system. Seismic data acquisition device uses MSP430F5438 as its CPU,which can effectively reduce the power consumption of system. We use the high precision microseismic probe, mount on the bolt and insert in rock mass, the output signal are converted by microchip’s A/D function into the digital signal with the help of high precision ADA4528 chip, the signal are transmitted to the signal receiving station through the Zigbee wireless devices,then transmitted to the ground hosts by optical fiber Ethernet . The host computer data processing software was written in VB2008, mainly realized the microseismic data collection and storage, real-time curve display and seismic tendency analysis, reports and print function.

The tendency of equipments maintenance in coal mine is predictive maintenance. In this paper, remote health diagnosis system of important mechanical electronic equipments in coal mine (abbreviated as 4M System) was introduced, and related development on equipment normal maintenance, on-line monitoring, malfunction simulation and predictive maintenance model, as well as the shortage existed in field operation, were summarized to give better direction on coal mine equipment maintenance.

To find out main controlling factors and applicable conditions of separated layer fracturing commingled producing for coalbed methane in Panzhuang, the geological and engineering factors of successful implementation was studied based on the sorting and analysis of the geological characteristics, reservoir fracturing hydraulic and drainage data by selecting production wells for more than five years as the research object. The results show that the key to success is to guarantee that the fracture spreads sufficiently within coal seams and is limited in height, in order to avoid the hydraulic connections between the coal seams and the roof and floor aquifers near the wells. The commingled producing will be successful by insisting on “continuously, slowly, stably” production policy when the original reservoir pressure, critical desorption pressure match or have a little different among the coal seams.

This paper is study on the regularity of strata behavior in 20104 working face. According to the 20104 fully mechanized caving face’s specific geological and mining conditions of Wang Jialing coal mine take the method of field measurement. The results showed that the coal mining face would have a sectional pressurized phenomenon, central pressure strength and first-come, subsequently ends to pressure less intensity; the work resistance of working face mainly between 18.2 ~ 33.0MPa ; the middle bracket dynamic load significantly during the pressure, and the central part of the frame work resistance close to the rating, finally research can lay a foundation for the fully mechanized caving face mining in other mines.

For current mining pipe connections of gas drainage in Chengzhuang coal mine has much defects，such as bulky, perishable, easy to water, larger human factors when pipe connections, a new type of gas drainage pipe connections is proposed, this deceive includes orifice flow control valve, the telescopic tube member, adjustable joints, are used PVC material and antistatic coal mine rubber and can adapt to changes in drilling height, can be adapted to changes in the borehole spacing, can be adapted to borehole angle changes, the roadway deformation ,it also has the function of orifice flow regulating Compared with the current pipe connections, it has a light weight, pipe connecting speed and efficiency significantly improved, anti-corrosion, effectively prevent the pipeline clogging of water and cinder.

By means of drilling, gas chromatograph analysis Yuxing coal mine 1601 face small mines firing old mined-out area inside the airtight site analysis. Shotcrete plugging, reinforcement sealed,drilling grouting effective underground mine fire control technical measures are used. The combustion of 1601 small mines old mined-out area is effectively governed, make small mines combustion effects on already made his mine safety in production is greatly reduced, effectively guide the mine safety production.

To prevent protected gas flooding to protective working face, cause its top corner and return air roadway gas overrun , based on gas migration rule in “three zones” of goaf overling strata, took use of high drilling to draiage prssure relief gas from proteccted seam; Through practical application in Yangdong mine 8458 working face, adop theoretical calculation and numerical simulation to determine the height of the fracture zone and desingn high drilling parameter; Results show that every drilling of the working face pure gas drainaging quantity increased from 0.5 m3 / min to 0.8 m3 / min, gas concentration of return air roadway reduced from 0.9% to 0.4% and gas concentration of the upper corner reduced from 1.2% to 0.6%, improved gas drainnage rate, ensured the safety and efficiency of recovery.

With the integration of coal resources and the increase of yield per unit , the original coal washing system can't meet the production requirements. Technical reorganization and expansion was conducted through optimizing the coal washing method and the workshop process arrangement, improving the production process and selection and installation of the main process equipment, according to the principle of saving investment and reducing impact on the existing production system. The improved coal preparation system has production capacity of 11.00 Mt/a, and has four kinds of production mode, which greatly improves the adaptability of coal preparation. Production practice shows that the improved system can not only adjust the product structure and reduce product moisture, but also reduce investment, and achieve the anticipated goal of reconstruction.

Aiming at the phenomenon of the law of strata behaviors being different between the below coal seam working face that the upper coal seam has been mined and common working face, the paper definition of the Loading Layer and the main Loading Layer based on the original principle about rock strata movement. The paper derives the expression of caving step length when considering the upper coal bottom failure depth. The paper analyzes the influence of the process of load-bearing layer rupturing and collapsing on the law of strata behaviors of coal seam working face. The results indicate that fracture form and motion feature of load-bearing layer has great influence on the law of strata behaviors and landmark movement, sometimes it plays a decisive role in it. Interlaminar fracture of load-bearing layer causing different strength and incidence roof weighting different strength and incidence superposes in working faces and causes the law working face weighting confusing. Rock fracture nearer to working face top has less effect on strata behaviors of working face and nearer to working face bottom. Finally, the results of the theory analysis are verified logicality and verifies the applicability widely used in many polymer melts.

This article illustrates the measuring principle of deep and surface displacements of surrounding rock of roadway, analyses the disadvantages of two kinds of conventional measuring methods，proposes a new combination multi-point displacement meter which can comprehensively measure deep and surface displacement of surrounding rock, improve the measuring precision and validity ,reduce observation station, and based on this new instrument illustrates a method of measuring and calculating the deep surrounding rock separation , real displacement and the ratio of deep and surface displacement, which provides scientifical and valid data for researching the movement rule of surrounding rock and designing roadway support reasonably.

Abstract：This article describes the concepts of the economic operation about the mine main fan system and the methods of the test and evaluation. Meanwhile, the paper analyzes the main factors which affected economic operation system of the mine main fan system, given the main problems of the fan system and proposed the ways to achieve economic operation. The results of this paper can guide the safe in operation of the mine main fan system.

This paper gets the parameters of temperature and concentration of oxygen at different distances of different measuring points in mined-out area and air return lane by site buried tube observation in the gob of Wugou coal mine CT101 workface. Through analysis the change rule of temperature and oxygen concentration of each measuring point, determine the scope CT101 mined-out area spontaneous combustion "three zones". At the same time, using the method of numerical simulation, to simulate temperature field in mined-out area, obtained the general law of a "three zones" of the mined-out are.

Coal-mine gas explosion accidents are of the most serious losses in all kinds of coal mine accidents, so the dangerous source of the gas explosion accidents were analyzed with the fault tree in order to build the accident chains based on the mechanism of gas explosion accidents in this study. The uncertainty and the different importance of dangerous source in the process of gas explosion accident were studied by using the fuzzy fault tree, and the importance degree of base case was obtained by using the median method when analyzing the calculation methods of fuzzy importance degree. Finally, an actual example verified the feasibility and scientificallness of risk pre-control of coal-mine gas explosion accidents based on the fuzzy fault tree, and then a new idea for the timely and accurate coal-mine gas explosion accidents early warning was put forward.

Some strata are difficult to be frozen for its thermal properties or water environment in some shaft construction projects by using artificial freezing method. A freezing suggestion of flowing two types of negative temperature solutions in a freezing pipe is proposed to intensify freezing. To verify the effect of such freezing method, single freezing pipe tests are conducted in a model test box using two sets of circulatory systems to provide calcium chloride solution of different negative temperatures. Three dimensional numerical analysis of intensified freezing is calculated by using FVM method. The intensified freezing section of freezing pipe has a boundary condition of different temperature, -35℃,-40℃ and -45℃. The mesh model is calculated to analyze temperature field distribution laws and characteristics of frozen wall in different level of freezing pipe. The results show that the difference of temperature can be realized between adjacent outer walls of the two different temperature sections of a freezing pipe. Such two different temperature freezing method can increase thickness, reduce average temperature and intensify cold energy dissipation.

Single bend screw drill tool is one of the important tools for implementation of horizontal directional drilling in coal mine. This paper analyses the stress and deformation of the single bend screw drill tool through the beam-column theory, and elucidates the relationships among changing dip force and changing azimuth force with bit pressure, the length of first beam, curvature radius of the borehole, bend angle, tool face angle and so on. According to the analysis of torque, axial load and centrifugal force, it is helpful to understand the working state of screw drill tool; and it is important for correct use, maintenance and successful directional drilling.

The mineralogical characteristics of the partings in the No.6 coal seam from the Dafanpu Mine of the Jungar Coalfield were studied using analytical procedures including X-ray diffraction (XRD), optical microscope, electron scanning microscope equiped with an energy dispersive X-ray spectrometer(SEM-EDX). The results showed that the main minerals in the partings were boehmite (60%) and kaolinite (40%), which had obvious genetic relations in optical microscope images. The Al-rich area was different from the Si-rich area in SEM-EDX Mapping images. The boehmite was transformed from kaolinite in the desilication. The chemical reaction reacted strongly in the space between crystal layers of kaolinite and strongly around the kaolinite surface.

In order to investigate the characterizations of the concentration, distribution patterns of rare earth elements(REE) in coals and the distrbution features of REE when coal seams invaded by magma at Yuandian No.2 Coalmine, ICP-MS,XRF,XRD were used to analyze the content of the bulk elements,the REE and mineral composition in 7 coal samples and 3 magmatic rock samples from No.72 coal-seam. The results shows that the REE in coals from No.72 coal-seam at Yuandian No.2 Coalmine are distributed in normal mass fraction levels comparede to the abundance of REE in China coal. The average content of REE in coals and nature coke were 88.87μg/g and 94.58μg/g. While the average value of LRRR/HREE were 8.58 and 6.80, and the REE distribution pattern is characterized by a “V-shape” cure whit obviously Eu negative anomaly with enrich of LREE and HREE depletion.The main REE-bearing clay minerals were changed and the abundance of LREE in coals were depletion as a result of the igneous invasion.

By implementing industrial analysis and elemental analysis of lignite and semi-coke of lignite,we could easily find organic ingredients and coalification of lignite have taken great places after low temperature pyrolysis upgrading technology.Their comparison of infrared spectroscopy showed that the main hydrophilic functional groups in semi-coke included –OH,–H,–NH and –O– ect.Their contents were lower than in lignite.Carried on particle size analysis and flotation experiments of semi-coke,adopted 0#diesel,kerosene,ZS and their combination,the results showed that flotation effect was better when using complex flotation reagents than single reagent.But no matter which kind of reagent institution was adopted,reagents consumption were both enormous,as well as the high ash of concentrate.By means of analyzing the reasons of enormous reagents consumption,we could drow the conclusion that high degree of porosity was the dominant factor.

Combined with the characteristics of international coal market itself, this paper establish the coal engineering enterprises diamond model in order to select overseas target market, quantify the various factors, set comprehensive assessment index system which including 6 first grade indices and 15 second grade indices, and determine the weights of assessment indices by the principle of analytic hierarchy process (AHP). Select the world's five major coal producing country, through a combination of quantitative and qualitative analysis, target market comparative diamond models are constructed under influencing factors to arrive at a composite score for each target market. the results showed that the elements of Indonesian market is relatively good for coal enterprises to enter; followed by Russia, Australia, and the Indian market, the U.S. market demand has a little growth, The most intense competition, and difficult to entre, the diamond model comprehensive evaluation index system can objectively reflect the competitiveness of the goal market, and provide a scientific basis for decision making of coal engineering enterprises to explore overseas markets.

Abstract: The basic theory of classical soil mechanics is based on saturated Water-Soil Two-Phase, and the sample of the three triaxial tests is required to be saturated. Aimed at the structure characteristics of silt that it is easily to be disturbed with water, the author makes the sample saturated with the method of back pressure and achieves ideal results. Meanwhile, the reasonable parameter of back pressure is obtained, focusing on the silt in Handan. It provides some references for silt samples saturated tests.

This paper firstly introduces entropy theory in the study of the risk assessment on chinese coal enterprises’ internationalization. Based on the theoretical framework of risk management in coal enterprises internationalization, by systemically analyzing the path, stage and risk of the development on domestic coal enterprises’ internationalization, this paper builds up a risk-based system of Chinese coal enterprises internationalization, combined with field research and surveys to complete of the assignment of risk indicators. On this basis, in using of entropy value method it carries out the analysis of the risk assessment on chinese coal enterprises’ internationalization, thus to complete the study of the risk assessment from qualitative to quantitative on chinese coal enterprises’ internationalization. The aim is to provide the experience for domestic coal enterprises’ internationalization.