新建突出煤矿“先抽后建”模式与实施路径

针对国家提出的加快煤层气地面开发和推广煤矿"先抽后建"理念,分析了新建突出煤矿"先抽后建"的基本特征,构建了"先抽后建"的时间-空间-安全条件模式模型与政策落实-技术研究-工程实施路径图,并对官寨煤矿工程实例进行了研究。研究得出:煤层气地面井抽采是煤矿区域瓦斯治理的创新举措,是推动实现新建突出煤矿"先抽后建"的有效途径;"先抽后建"模式为科学规划煤层气抽采与矿井建设的工程分区,统筹衔接和协调实施煤层气与煤炭开发;实施路径是在煤矿筹建阶段明确落实"先抽后建"政策的总体方案,根据项目可行性研究的成果,研究编制"先抽后建"的技术实施方案,按照地面钻井-瓦斯先抽-矿井后建的步骤进行"先抽后建"的工程实施。现场工程实践显示,官寨井田煤层气开发与矿井建设工程"先抽后建"方案可行,具有典型的代表性和很好的借鉴意义。

影响煤矿瓦斯突出的地质因素分析

影响瓦斯突出的主要地质因素包括地质构造、煤层与围岩、水文地质等。文章全面分析了这三个因素对瓦斯突出的具体影响,结果表明最主要地质因素是地质构造,尤其是断层构造,在煤矿区最为发育,对瓦斯突出也控制最强;其次是煤层与围岩特征,尤其煤层厚度和煤层埋藏深度对瓦斯突出具有较强的控制作用;影响最弱的是水文地质特征,它要造成瓦斯突出还需依靠更多其他因素。希望通过上述分析,为煤矿预防瓦斯突出提供帮助。

基于多层关联规则算法的煤矿突出预警模型

为提升煤矿突出预警精度,提出基于多层关联规则算法的煤矿突出预警模型。分析造成煤矿突出问题产生的主要因素,并以此为基础,由地质构造、煤层赋存参数与瓦斯参数3方面出发,选取压扭性断层、煤厚变化量以及煤层瓦斯含量等煤矿突出预警指标,构建煤矿突出预警指标体系。采用层次分析法构建煤矿突出预警模型,利用多层关联规则算法挖掘模型内同层指标关联规则与跨层指标的关联规则,确定预警模型内各指标的权重,根据组合权重确定煤矿突出预警结果,并将预警结果分为安全、威胁、危险与突出4个等级。实验结果显示,所研究模型的预警精度基本保持在99%以上。

煤矿瓦斯突出的神经网络预测

煤与瓦斯突出的预测是煤矿安全工作的主要工作之一.本文通过建立煤与瓦斯突出的BP神经网络预测模型,对瓦斯矿井的工作面和区域进行突出危险性预测.根据本文的计算结果和实际情况的对比,BP神经网络预测模型在煤矿瓦斯突出预测方面有着一定的准确性,是可行的.

近距离下保护层开采的瓦斯立体空间综合治理技术

煤与瓦斯突出煤矿的安全有效开采,一直是煤矿开采行业面临的难题之一。目前开采具有煤与瓦斯突出的煤层,最有效的区域综合防突措施为保护层开采。其包括上保护层和下保护层开采。在下保护层开采过程中特别是近距离下保护层开采时,保护层回采工作面的瓦斯治理是一个制约安全生产的难题。本文以沈煤集团西马煤矿为例,探讨了该煤矿近距离下保护层开采时,对保护层及被保护层的瓦斯采取立体空间抽采治理技术,有效地解决近距离下保护层开采过程中的保护层回采工作面回顺尾巷、工作面及回风瓦斯超限难题。希望能为行业提供一定的参考和借鉴。

THE RHEOLOGICAL PROPERTIES AND OUTBURST MECHANISM OF GASEOUS COAL

Coal and methane outburst is one of the harmful disasters in coal mines. We have studied the rheological properties of gaseous coal in laboratory and obtained its rheological fracture principle. This principle can better explain and describe the outburst mechanism of gaseous coal. Thereby a rheological hypothesis of coal and methane outburst is put forward in this paper.

△P index with different gas compositions for instantaneous outburst prediction in coal mines

In this study we measured the △P(initial speed of gas emission) index with different gas concentrations of carbon dioxide(pure CO2,90% CO2+10% CH4,67% CO2+33% CH4,50% CO2+50% CH4,30% CO2+10% CH4 and pure CH4) of coal samples from the No.2 coal seam in the Yaojie Coal Mine,Gansu province,China.The effect of carbon dioxide concentration,gas composition,coal strength and particle size of coal samples on the △P index was investigated.The experimental results show that with gas of various compositions,the △P value of three samples were clearly different.The △P index of coal samples A,B and C(0.2～0.25 mm) were 4,6 and 7 with pure CH4 and 22,30 and 21 when pure CH4 was used.Carbon dioxide concentration affects the △P index markedly.The △P index increases with an increase in carbon dioxide concentration,especially for coal B.Hence,the △P index and K(another outburst index) values tested only with pure CH4 for prediction of the danger of outburst is not accurate.It is important to determine the initial speed of gas emission given the gas composition of the coal seam to be tested for exact outburst prediction.

Application of the catastrophe progression method in predicting coal and gas outburst

Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.

Influence of magma intrusion on gas outburst in a low rank coal mine

The effect of magma intrusion on gas outburst is illustrated by a case study of the exposed magma intru- sion in the 313 mining area, upper coal seam Number 3, in the Qiwu Mine located in Shandong province. Vitrinite reflectance, mercury injection, and maceral statistical analysis are used to characterize the coal. The aspects of coal metamorphism include changes in micro-components as well as in coal structure, the formation of new substances, and changes in gas absorption and storage. The results show that vitrinite reflectance increases within the region influenced by magma intrusion. The metamorphosed region may be divided into a weakly affected belt, a medium affected belt, a strongly affected belt, and a completely affected belt. Compared to the unaffected coal the total pore volume, as well as the amount of big and middle sized holes, increases while the number of transition holes and micro-pores decreases. This diminishes the absorption capacity of the matrix but enlarges the total gas storage space. Vitrinite con- tent initially decreases slightly but then increases rapidly while the inertinite content increases at first but then decreases. Exinite content decreases, then increases, and finally drops to zero. Higher vitrinite, and a lower inertinite, content increase gas absorption ability. This balances reduced adsorption caused by changes to pore structure. Consequently, gas adsorption capacity is not substantially reduced as the coal rank increases. Thermal metamorphism of the coal produces CH4 and other hydrocarbons that increase the total gas content in the coal seam. Asphaltene migrates into the medium and weakly affected regions filling in the pores and fractures there. This plugs the pathway for gas transport. A barrier is formed that hinders gas flow. C02, H2S, N2, and other gases carried in by the magma react to produce C02, which increases in relative concentration and enhances the risk of gas outburst. The two barriers, magma intrusion on one side and the medium and weakly affected belts on the other, as well as the unaf- fected coal seam itself, trap a large amount of gas during the thermal activity. This is the basic reason for gas outburst. These conclusions can enlighten activities related to gas prevention and control in a low rank coal mine affected by ma^ma intrusion.

Comparing potentials for gas outburst in a Chinese anthracite and an Australian bituminous coal mine

Gas outbursts in underground mining occur under conditions of high gas desorption rate and gas content,combined with high stress regime, low coal strength and high Young's modulus. This combination of gas and stress factors occurs more often in deep mining. Hence, as the depth of mining increases, the potential for outburst increases. This study proposes a conceptual model to evaluate outburst potential in terms of an outburst indicator. The model was used to evaluate the potential for gas outburst in two mines, by comparing numerical simulations of gas flow behavior under typical stress regimes in an Australian gassy mine extracting a medium-volatile bituminous coal, and a Chinese gassy coal mine in Qinshui Basin(Shanxi province) extracting anthracite coal. We coupled the stress simulation program(FLAC3D) with the gas simulation program(SIMED II) to compute the stress and gas pressure and gas content distribution following development of a roadway into the targeted coal seams. The data from gas content and stress distribution were then used to quantify the intensity of energy release in the event of an outburst.

Data Processing Model of Coalmine Gas Early-Warning System

The data processing mode is vital to the performance of an entire coalmine gas early-warning system, especially in real-time performance. Our objective was to present the structural features of coalmine gas data, so that the data could be processed at different priority levels in C language. Two different data processing models, one with priority and the other without priority, were built based on queuing theory. Their theoretical formulas were determined via a M/M/I model in order to calculate average occupation time of each measuring point in an early-warning program. We validated the model with the gas early-warning system of the Huaibei Coalmine Group Corp. The results indicate that the average occupation time for gas data processing by using the queuing system model with priority is nearly 1/30 of that of the model without priority.

Technology of gas drainage and utilization in Huaibei mining area

With the characteristics of coal seam geology and gas occurrence,a'ground-underground' integrated gas drainage method was formed,which can relieve gaspressure and increase permeability by mining the protection seams in conditional regions.After coal seam gas drainage,high gas outburst seam was converted to low gas safetyseam.In the coal face mining process,safety and high efficient coal mining were realizedby the measure of gas-suction over mining.In addition to the drainage gas for civil gasand gas power generation,the Huaibei Mining Group has actively carried out research onthe utilization technology of methane drainage by ventilation.On the one hand,it can saveprecious energy;on the other hand,it can protect the environment for people's survival.In2007,the amount of coal mine gas drainage was 120 hm3;the rate of coal mine gasdrainage was 44%.Compared with the year 2002,the amount of coal mine gas drainageincreased by two times.Meanwhile,the utilization rate of gas increased rapidly.

STUDY ON THE METHOD FOR FORECASTING DANGEROUSNESS OF COAL FACE AND HEADING FACE OUTBURST BY TWO TEMPERATURE INDEXES

In line with the sensitivity of coal drillings temperature and coalbed temperature to the dangerous zone of coal and gas outburst, two temperature sensitive indexes (△Tm, △tm) for forecasting dangerousness of coal face and heading face outburst are defined, and deal with the foundation on drillings and coalbed temperatures used as sensitive indexes and the principle and method of determining drillings and coalbed temperatures. On the basis of this, we put forward the method for forecasting dangerousness of coal face and heading face outburst by two temperature sensitive indexes and determine the critical values of two temperature sensitive indexes (△Tm= 5.5℃, △tm = 4.5℃) by in-situ observation and requirement for determining sensitive index.

Determination of indices and critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine

Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices： gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/（g min^1/2） and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.

Study on comprehensive gas control techniques and practice in coal mines

The origins and main control methods of gas in coal seams were introduced cursorily, and the processes that need to be done in controlling gas, which includes prediction of gas emissions, drainage systems, the means of prevention of gas outbursts, and some suggestions were put forward. The characteristic of different gas emissions and the corresponding counter measures were presented, and ＆ case study of simultaneous extraction of coal and gas in Xieyi Coal Mine was carried out by coal mining and gas extraction without coal-pillar. The field application shows that gas drainage ratio in panel 5121（0） averages about 90% and reaches as high as 95~/0, which will give beneficial references to gas control in coal mines.

Application study on complex wetting agent for dust-proof after gas drainage by outburst seams in coal mines

After gas drainage, the outburst seam is dry and, consequently, during subsequent mechanized mining, unwanted dust production is extensive. Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust. Considering these factors, this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent, then configuring five kinds of wetting agents by adopting various doses and types of surfactants, neutral inorganic salts and chemical additives, etc. After purchasing DA-85 and SRJ-1 wetting agent, the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method. Wetting agent A was confirmed to have the best comprehensive effect. The experiments were optimized by measuring and comparatively analyzing contact angles of pure water, SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument （HARKE- SPCA）. By comparative analysis, dust-proof effects of seam, dynamic pressure water infusion and high- pressure spray in the tunneling face at the Daning coal mine using pure water, wetting agent SRJ-1 and A, it was determined that after using wetting agent A, the average dust concentration in the place of the mining machine driver, 10 m and 110 m away from the tunneling front is approximately 300 rag/ m^3, 240 mg/m^3 and 100 mg/m^3, respectively, This practice increased the dust-proof efficiency dramati- cally and achieved a good comprehensive dust-proof effect.

A study of law of coal-and-gas outburst ＆ its controlling factors in Kailuan Mine Area, China

On basis of an analysis of the geological condition, law of gas outburst and materials about coal-and-gas outburst, this paper summarized the characteristics associated with coal-and-gas outburst of Zhaogezhuang Mine and studied the factors controlling coal-and-gas outburst such as stress, coal structure and gas pressure, content of gas. Then, based on a comparison of effects of in-situ stresses, coal structure and gas on coal-and-gas outburst of Zhaogezhuang Mine, the paper concludes that the major geological factors that control coal-and-gas outburst of Zhaogezhuang Mine are in-situ stresses and coal structure.

Research into comprehensive gas extraction technology of single coal seams with low permeability in the Jiaozuo coal mining area

For a low permeability single coal seam prone to gas outbursts, pre-drainage of gas is difficult and inefficient, seriously restricting the safety and efficiency of production. Radical measures of increasing gas extraction efficiency are pressure relief and infrared antireflection. We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial （Group） Co. as our test area, studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone. On that basis, we further investigated and practiced the exploitation technology of shallow drilling, fan dril- ling and grid shape drilling at the working face. Practice and our results show that the stress relaxation zone is the ideal region for quick and efficient extraction of gas. By means of an integrated extraction technology, the amount of gas emitted into the zone was greatly reduced, while the risk of dangerous outbursts of coal and gas was lowered markedly. This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area.

STUDY ON THE THRESHOLD GAS PRESSURE IN COAL AND GAS OUTBURST

Based on the statistical data of 26 outburst prone coal seams in China, this paper presents the relationship among the threshold gas pressure in coal and gas outburst and the volatile content and hardness of coal by mathematical statistics. The threshold value of gas pressure for outburst pmin in MPa may be calculated by formula Pmin =5(0. 1+0. 07Kf), where / is the hardness and V the volatile content (%) of a soft bed. In China, the value of Pmin of some outburst prone coal seams ranges from 0. 57 to 0. 1 MPa.

Issues in the outburst prevention work of coal mines in Guizhou Province and the analysis of its countermeasures

In order to reduce the occurrence of coal and gas outburst accidents, and improve the capability to prevent gas hazards and realize the safe and efficient mining of coal enterprises. The distribution of the outburst coal mining area of Guizhou Province and the status of coal and gas outburst and the problems in the current outburst prevention methods were analyzed. The main issues were pointed out such as the lack of regional outburst prevention measures, unsatisfactory effect in drainage, poor management and implementation, as well as personnel that need more training. The prevention situation of coal and gas outburst in Guizhou Province was considered. In accordance with the above problems, from the perspective of strengthening geological exploration, testing coal seam parameters, studying outburst prevention technologies, deploying mining systems rationally, improving mine safety management systems, and strengthening protection facilities and other aspects, a targeted outburst prevention measure and proposals were put forward.