The study of coal mine equipment’s comprehensive evaluation index system and evaluation method

1 Limitations of current evaluation index system of coal mine equipment While the operating mechanism of coal enter-prise changes, the equipment management’s state isimproved constantly. But the enterprises’ equipmentmanagement developed unevenly, presenting a trendof polarization. Some listing coal enterprises that havegood mechanism and bent on making progress reformand innovate constantly. They have formed the man-agement mode of equipment with their own charac-teristics. But the effect …     

Experimental simulation and numerical analysis of coal spontaneous combustion process at low temperature

The characteristic of coal spontaneous, combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large-scale experimental unit loading coal ! 000 kg. According to the field change of gas concentration and coal temperature determined through experiment of coal self-ignite at low temperature stage, and on the basis of hydromechanics and heat-transfer theory, some parameters can be calculated at different low temperature stage, such as, oxygen consumption rate, heat liberation intensity. It offers a theoretic criterion for quantitatively analyzing characteristic of coal self-ignite and forecasting coal spontaneous combustion. According to coal exothermic capability and its thermal storage surroundings, thermal equilibrium is applied to deduce the computational method of limit parameter of coal self-ignite. It offers a quantitative theoretic criterion for coal self-ignite forecasting and preventing. According to the measurement and test of spontaneous combustion of Haibei coal, some token parameter of Haibei coal,spontaneous combustion is quantitatively analyzed, such as, spontaneous combustion period of coal, critical temperature, oxygen consumption rate, heat liberation intensity, and limit parameter of coal self-ignite.     

Simulation modeling on the growth of firm＇s safety management capability

Aiming to the deficiency of safety management measure, established simulation model about firm’s safety management capability(FSMC) based on organizational learning theory. The system dynamics(SD) method was used, in which level and rate system, variable equation and system structure flow diagram was concluded. Simulation model was verified from two aspects: first, model’s sensitivity to variable was tested from the gross of safety investment and the proportion of safety investment; second, variables dependency was checked up from the correlative variable of FSMC and organizational learning. The feasibility of simulation model is verified though these processes. Supported by the State Social Science Fund of China(07BJY080)     

Quantifying the emission’s impact of coal mining activities on the environment and human health in process

Discharges and emissions in the coal mining process have a strong effect both on the environment and on human health. This problem is usually be a negative one and has only been recognized qualitatively, due to the lack of effective quantitative methods. Based on emergy theory and accounting methodology, a set of quantitative methods for accounting the environmental support due to pollutants emissions was first introduced. Then impacts on environment and effects on human health were quantified using the unified units. The results indicated that water pollutants caused more impacts on the environment than air pollutants did, i.e., more environmental contributions are needed to dilute and absorb water pollutants. The occupation of land caused by coal mining gangue waste stacking has led to a huge loss of environmental services over the years. Moreover, the potential damage on the human condition health caused by CO₂ through climate change cannot be ignored. Finally, the impacts of mining activities on environmental and human health in unified units are shown to provide a quantitative insight into the disadvantage of coal mining. The comparable results of the method indicate the different influence of various pollutants and the contribution of ‘natural capital’ directly. This work is a part of ongoing thermodynamic input-output analysis and life cycle analysis of coal mining systems (which are in process.)     

Preparation of activated carbon with low ash content and high specific surface area from coal in the presence of KOH

An activated carbon with ash content less than ]0% and specific surface area more than 1600 m^2/g was prepared from cool and the effect of K-containing compounds in preparation of cool-based activated carbon was investigated in detail in this paper. KOH was used in co-carbonization with coal, changes in graphitic crystallites in chars derived from carbonization of coal with and without KOH were analyzed by X-ray diffraction (XRD) technique, activation rates of chars with different contents of K-containing compounds were deduced, and resulting activated carbons were characterized by nitrogen adsorption isotherms at 77 K and iodine numbers. The results showed that the addition of KOH to the coal before carbonization can realize the intensive removal of inorganic matters from chars under mild conditions, especially the efficient removal of dispersive quartz, an extremely difficult separated mineral component in other processes else. Apart from this, KOH demonstrates a favorable effect in control over cool carbonization with the goal to form nongraphitizable isotropic carbon precursor, which is a necessary prerequisite for the formation and development of micro pores. However, the K-containing compounds such as K2CO3 and K20 remaining in chars after carbonization catalyze the reaction between carbon and steam in activation, which leads to the formation of macro pores. In the end an innovative method, in which KOH is added to coal before carbonization and K-containing compounds are removed by acid washing after carbonization, was proposed for the synthesis of quality coal-based activated carbon.     

Fibre glass reinforced plastics bolt‘s application in coal wall support of stoping tunnel

This article set forth two types of destructive form of stopping tunnel coal wall: de-structive form in coal and destructive form in interface of coal layer. In addition, the mecha-nism of destruction in stopping tunnel coal wall is analyzed.     

Nappe structure＇s kinetic features and mechanisms of action to coal and gas outburst

逆冲推覆和重力滑覆的共性特征是存在一个以相对低的强度和高的剪切应变为特征的滑脱面或拆离层,分隔着其上下力学性质和应变特征不同的两盘。推覆构造对煤与瓦斯突出的作用机制主要表现为2个方面：①推覆构造形成过程中低角度滑动对煤体产生广泛的压剪作用,使得煤层作为相对软弱层面结构发生广泛的层域破坏和面域破坏,构造煤非常发育;②推覆构造的挤压应力环境以及地层增厚效应为瓦斯赋存提供了有利条件,低角度的主滑断裂面（大多为逆断层或逆掩断层）往往构成较好的瓦斯封闭系统,对瓦斯的赋存起一定的控制作用;推覆构造派生的具有压性特征的结构面形成了对煤层瓦斯系统的封闭作用。总体上推覆构造对煤与瓦斯突出的作用机制体现在其为煤与瓦斯突出创造了物质基础——高含量的瓦斯和低强度的煤体。     

The study of coal mine equipment＇s comprehensive evaluation index system and evaluation method

Equipment management is one of the important parts of business administration of coal. Most of coal mines take no account of their equipment management, and have no comprehensive and effective evaluation index system. Based on the analysis of the equipment evaluation measures of reform and the applications, the paper built up a comprehensive and effective evaluation index system of coal mine equipment, and improved the evaluation method with the use of fuzzy theory, analytic hierarchy process and entropy method.     

Investigation on displacement field characteristics of tunnel＇s surrounding rock and coal seam at FMTC face

The change rules of displacement field characteristics of coal seam and tunners surrounding rock were obtained by means of numerical simulation-FLAC^3D and site observation, and according to engineering geology and exploitation technology of 1151 （3） fully mechanized top coal caving （FMTC） face in Xieqiao colliery. The research＇s results show that the top coal displacement on the top of FMTC face is apparently larger than those of the middle and the bottom, the top coal begins to move in the front of the face＇s wall, and the sub-level top coal-rock moves ahead of the low-level top coal-rock, the vertical displacement of top coal-rock increases gradually as the decreasing of distance to face Top coal and overlying strata in vertical direction are always in compressed state in the front of face, then the top coal begins to separate from the overlying strata at the upside of face. The support loading at face is mainly the deformation pressure due to top coal and main roof＇s movement, and it is not suitable for the FMTC face with traditional support design. Surrounding rock movement of the face is of near-field effect, the surrounding rock deformation is acute greatly near to the face, the ideas of supporting design for the tailentry and headentry should be changed from loading control to deformation control.     

Macro mechanical parameters’ size effect of surrounding rock of Shuibuya project’s underground power station

Introduction[1] Situated in the Badong County of Hubei Province, Shuibuya Project is a large project mainly used to generate electricity as well as prevent or control flood and facilitate shipping etc. The project has four gen- erators, the capacity of which is 400 MW and the total capacity is 1 600 MW. Power station lies on the right side of the Qingjiang River, from the top to the bottom the workshop’s strata are composed of Maokou for- mation ( P1m), the first 15 sections of Xixia fo…     

Application wavelet of the analysis for identification of acoustic issue’s signals

Acoustic issue at deformation and destruction of materials carries initself weight of theinformation onthe physical processes happeningin structure of a material , mechanisms ,to energy of destruction,intensi-ty ,speed of deformation,etc . The Majority of researches inthe given areais devoted to the analysis of setof signals during tests of materials and designs .Few works are devoted to the analysis of structure of indi-vidual signals with the purpose of identification origin.It is connected …     

Major Tasks of the Ministry’s Department of Planning and Development for 1996

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Evolution of Water Hazard Control Technology in China’s Coal Mines

Mine Water and the Environment - We analyzed the regional nature of China’s coal mine water disasters based on three aspects: the main water source, water-conducting passages, and threat...     

Stress state of rocks surrounding excavations under variable Young’s modulus

Deep-level mining needs extra data on physical behavior of rocks at great depths (under high stresses). Without such data, any computations for deep-level technologies based on analogy with shallowdepth technologies are non-diagnostic. Elastic moduli of rocks may depend on the accumulated plastic deformation and their reduction is considerable in the known tests of metals. It seems interesting to study the influence of this property of rocks on distribution of residual stresses and displacements. Elastic transformation of an excavation after drivage (relief of stresses) largely affects surrounding rock mass and results in origination of a transition layer around the excavation. A local drop of deformation energy takes place in the surrounding rocks, which reduces stress concentration. The problem is studied based on an analytical solution obtained for a deep round excavation subjected to constant value compressive stresses at infinity and a solution taking into account the Young modulus. The article offers an algorithm for geomechanical condition of rocks and determines ranges for stresses and displacements in the zone of influence of excavation. Examples of calculations are given, and the results are discussed.     

Dynamic Characteristics of Water Inflow from a Coal Mine’s Roof Aquifer

The static and dynamic inflow of water from the roof aquifer changes as mining progresses. We used a second-order dynamic model to describe the water inflow process. The parameters of the water inflow model were solved using actual drainage from roof aquifers at nine working faces in the Yuanyanghu mining area of the Ningxia Autonomous Region, China, as well as the peak water inflow values, their locations, the equilibrium values of water inflow, and their initial occurrence locations. The parameters of the second-order dynamic model of water inflow were inversely calculated. The peak values of water inflow without drainage were also calculated. The results indicate that pre-drainage of roof water significantly weakens the intensity of water inflow during the mining process, reducing peak values by more than 72%. The characteristics of the water-conducting fractured zones determine the major drainage locations, while the water-rich and water-conductive nature of the direct discharge aquifer affects the water inflow equilibrium values and initial occurrence positions. The results show that the model parameters and characteristic values of water inflow are determined by the hydrogeological nature of the roof strata, water-conducting fractured zone(s), and mining speed.

     

Causes of Decreased Discharge and Damage to a Dewatering Well’s Gravel Coat

Drainage wells used in lignite mining have to be operated at high efficiency in order to achieve a targeted drawdown in the shortest time period possible. However, oversizing of pump units and excessive pumping can cause accelerated aging of wells and over time, decrease a well’s drainage efficiency. This article analyzes the case of a well that was operated for 10 years and then abandoned at a lignite mine. A common practice in installing dewatering wells in Poland is to protect the well screen with a pre-fabricated granular layer (called a “gravel coat”) that is attached to the screen when it is lowered into the hole. The combination of the gravel coat and well screen is surrounded by a protective gravel pack. Samples of the gravel coat were obtained from the abandoned well. The percentage by weight of precipitates in, and the porosity of the gravel coat from the abandoned well were determined and compared with the properties of new gravel coat material. Tests were conducted in the laboratory to compare hydraulic losses, apparent seepage velocity, effective velocity, and the hydraulic efficiency of the well’s gravel coat. The results of the tests explain the low hydraulic efficiency of the abandoned well and the origin of the damage to the gravel coat. The actual yield was also compared with the calculated theoretical safe yield, which was estimated based on the results of geological records from the construction of the well.     

Considerations of the Development of China’s Coal Technology during 9th Five－Year Plan Period

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The Effects of Caving of a Coal Mine’s Immediate Roof on Floor Strata Failure and Water Inrush

Large scale roof strata caving that occurs during coal extraction can irreversibly damage floor strata and result in riskier mining operations. Four research models incorporating floor water pressure were assessed for floor strata failure, using eight methods and two classification systems. A connection between floor strata failure and the coefficient of impact risk was developed. The derived equations represent a potentially effective method for providing a preliminary assessment of the risks associated with floor strata failure due to caving. A classification system of floor failure potential can be constructed to minimize risks during mining.