China
Africa
Explore chapters and articles related to this topic
How Coal is Mined
Published in H. Townshend-Rose, The British Coal Industry, 2017
An efficient system of ventilation in a coal-mine is essential for safety and efficiency. Methane gas, known as ‘firedamp’, is given off by the coal seams and a concentration of 5 to 15 per cent in the air forms a highly explosive mixture. Pits and individual seams vary in the amount of firedamp given off, but in a ‘gassy’ pit very stringent precautions are taken to prevent the introduction, acci¬dental or otherwise, of naked lights. Smoking is prohibited and pipes, cigarettes, matches and lighters are ‘contraband’ which may not be taken into the pit. Electricity for power or general use is prohibited or subject to severe restrictions, and handlamps or caplamps, whether oil or electric, must be of approved pattern and properly maintained. Some pits, however, are gas free and known as ‘naked light’ pits.
Safety Issues in Opencast and Underground Mines
Published in Debi Prasad Tripathy, Mine Safety Science and Engineering, 2019
Explosion accidents have affected the mining industry around the world. Explosions are considered to be a low-frequency, high-consequence hazard. Explosions in underground coal mines are due to firedamp, coal dust, a combination of both, or water-gas formation. Firedamp explosion is also known as methane explosion. It is formed in mines when flammable gases, especially methane, mixes with the heat sources and there is not enough air to dilute the gas to levels below its explosion point. Coal dust can develop into explosion when ignited. Table 2.8 presents data for the number of explosion accidents that killed ten or more workers in Indian coal mines.
Firedamp drainage optimization using geotechnical and Cfd modelling techniques
Published in Heping Xie, Yuehan Wang, Yaodong Jiang, Computer Applications in the Mineral Industries, 2020
T.X. Ren, J.S. Edwards, D. Whittles, D.J. Reddish
The primary objective of firedamp drainage is to intercept methane from its sources by drilling boreholes into adjacent strata/seams, allowing methane to be sucked into a steel pipe system, and subsequently discharged either into return air below ground, to atmosphere at the surface of the mine, or into a delivery pipe for utilization. A variety of methane drainage techniques have been developed for capturing methane gas in mine workings. Figure 1 illustrates the various post-drainage techniques for a longwall face. In practice, these methods are diverse and used to large extent on the basis of rules of thumbs.
Prediction of gas emission zone width in laneway’s coal seam based on slippage effect of gas seepage
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
The accurate prediction of gas emission amount not only directly affects the safety and efficiency of mine production, but also plays an important role in improving the economic and social benefits of coal mines. Wang, Chen, and Yang (2009), Abouna (2012) and Patrick (2017) give the calculation method of gas emission for underground coal mines, and point out that with the complexity of coal mining conditions and the increase of coal mining depth, the amount of gas emission increases. Hu et al. (2020) proposed a prediction model for workers at the floor coalbed to calculate gas emission on site and put forward a finite-element numerical simulation for researchers to predict gas emission from the floor coalbed. Wang and Du (2020) summarize gas compound dynamic disasters in China, gas emission from coal wall will cause gas disaster accidents occur frequently and seriously threatens the safety of mine production. In recent years, many scholars focus on the prediction of gas emission when fully mechanized mining is widely used in the coal mine. Karacan, Ricardo, and Gerrit (2012) established geostatistical modeling of the gas emission zone and its in-place gas content for Pittsburgh-seam mines using sequential Gaussian simulation. Si et al. (2015) proposed model a conceptual model for gas emission zones through monitoring gas dynamics in multi-level longwall top coal caving of ultra-thick coal seams. Yang et al. (2018) analyzed the outburst mechanism of tunneling through coal seams and the safety strategy by using “strong-weak” coupling circle-layers, and pointed out that the mining speed has been greatly improved, and the gas emission amount is also increasing, gas disaster has become increasingly serious. Frid (1997) and Chen, Xiao, and Zou (2017) reflect coal and gas outburst through the research on mechanism of quantity discharge of firedamp from coal drift of headwork surface. Therefore, gas accidents are most likely to occur in the working face of coal roadway. The focus of gas disaster prevention and control in coal mine should be effective prediction of gas emission amount and prevention of coal and gas outburst in the working face.
Study on Dynamic Prediction Model of Gas Emission in Tunneling Working Face
Published in Combustion Science and Technology, 2022
Hao Wang, Enyuan Wang, Zhonghui Li
Because non-contact method may be unstable in practical application, in terms of applicability in the field, contact method is still preferred for predicting coal and gas outbursts in coal roadways in China. Coal and gas outburst process is the phenomenon that a large amount of high-pressure gas is spewed out quickly through the cracks in coal and rock mass, which causes a large amount of gas accumulation in front of the working face. The more serious the outburst is, the larger the gas emission, and the process is related to gas pressure, ground stress, and the coal properties. However, in front of the coal roadway tunneling working face, gas pressure, ground stress, and coal properties cannot be directly measured. Therefore, timely and accurate prediction of gas emission during coal roadways driving is undoubtedly of great significance to mine gas control. Based on the above analysis, some scholars proposed to establish a gas emission model to predict coal and gas outburst. Chen et al. (2017) researched on the mechanism of quantity discharge of firedamp from coal drift of headwork surface, which is related to the coal and gas outburst, and calculation formula of gas flow in coal wall is established. Rodríguez et al. (2009) established a simplified mathematical calculation model to analyze the amount of gas emission in the process of roadway tunneling in carboniferous strata based on the average gas flow. Lunarzewski (1998) proposed a likewise novel Lunagas method which is available for prediction of gassiness in development roadways in coal.Yanget al. (2015) analyzed the characteristics of gas change at a mining face based on the elliptic orbit model, which was effective to evaluate the gas flow state. Wu et al. (2014) used gray model with fractional order accumulation to predict gas emission. After considering the influence factors of gas emission, Chen et al. (2016) put forward the dynamic gas emission model at the heading face. The above studies have made different methods to predict the gas emission in the mine or working face, but the accuracy of most prediction models of gas emission is relatively low, with poor accuracy, without strictly considering the influence of factors such as coal properties, gas parameters, excavation process, and time on the gas emission. In this paper, the components of gas emission in heading face are firstly determined. Then, the gas flow laws of falling coal and coal wall are analyzed, respectively, and the gas emission prediction model based on the gas adsorption parameters of coal seam with changing in-situ stress of gas pressure and permeability is obtained. The prediction results are compared with the conventional prediction index of coal and gas outburst and the old prediction model of gas emission. The research results have important practical significance for improving the safety of working face.