Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China

Cao, Zhiyi; Ren, Yulou; Wang, Qinting; Yao, Banghua; Xin-chao, Zhang

doi:10.1155/2021/6630462

“…Therefore, after gas is gushing out, it is easy to flow through the goaf and flow under the drive of air pressure. In the "U" type ventilation working face, when the air flow enters the stope from the inlet roadway, the gas in the goaf brings out to the working face, causing the gas concentration in the working face [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Li

¹

,

He

²

,

Xu

³

2021

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The overrunning disaster of harmful gas tends to occur in the working face in thick coal seam with high gas concentration, as the fully mechanized caving stope has the characteristics of high mining intensity, high remnant coal, and high gas content. Therefore, the disastrous mechanism and concentration distribution of gas migration in fully mechanized caving stope are the theoretical basis for gas control scheme. Based on the 7607 working face in Wuyang coal mine, the gas emission quantity in working face is comprehensively analyzed by field measurement in this paper. The gas leakage field, oxygen concentration field, and gas concentration field in 7607 working face are simulated by establishing the equal proportional numerical model. Due to the increase of air leakage in working face caused by the high alley pumping drainage, the risk of coal spontaneous combustion is also analyzed, when gas extraction in goaf is carried out. The research results show that the gas drainage technology in high drainage roadway has a remarkable effect on the gas overrunning phenomenon. The gas concentration near the upper corner of the working surface has been reduced from 0.7%-1% to 0.5%. At the same time, it is necessary to pay attention to the risk of coal spontaneous combustion in the goaf for gas drainage in the high drainage roadway. The width of the oxidation zone in the goaf is about 25 m deeper than that before the drainage. Research results provide the references for gas control technology and coal spontaneous combustion prevention in similar working faces.

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“…The accurate measurement of particle size distribution (PSD) of coal samples is significant to both scientific research and engineering, such as coal combustion [1][2][3][4][5], coal chemical industry [6][7][8][9], adsorption and desorption [10][11][12], and coal and gas outburst [13,14]. There are more than one hundred methods and instruments to measure particle size distribution, including sieving, settling velocity measurements, laser diffraction (LD), photon correlation spectroscopy, sound spectrum method, dynamic light scattering method, scanning electron microscope, and X-ray diffraction [15][16][17][18][19][20]. Of these methods, sieving and LD particle analyzers are widely used for measuring general coal particles (>10 μm) because of their high accuracy, simple operation, fast speed, and high repeatability.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on the Particle Size and Shape Distribution of Coal Drill Cuttings by Dynamic Image Analysis

Zhang

¹

,

Lan

²

,

Wen

³

et al. 2021

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Particle size and shape distribution can be measured in great detail by dynamic image analysis (DIA). The narrow dispersion of repeated experiment results indicates that the particle size distribution can be obtained with high reliability. Particle size distribution can be better fitted to Rosin-Rammler equation than Gaudin-Schuhmann distribution and the lognormal distribution. The spread parameter ( m ) and the location parameters ( d 0 ) of the Rosin-Rammler equation can be calculated precisely. We analyzed the similarities and differences between the different particle shape distributions. The distributions of form factor and circularity are right-skewed distributions, while the distributions of ellipse ratio, irregularity, and aspect ratio obey a normal distribution. By studying the relation between particle size and shape, we find a linear relationship between the ellipse ratio and the Legendre ellipse diameter on the logarithmic scale.

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“…Besides, CO (carbon monoxide) is widely recognized as the most important symbol gas for detecting coal spontaneous combustion at the early stage [2]. However, CO overrunning occurs in a large number of field practices in coal mines, especially in mining the thick coal seam [3,4]. Meanwhile, CO is a toxic and harmful gas, which poses a serious threat to the safety and health of miners [5].…”

Section: Introductionmentioning

confidence: 99%

Evolution Law of Gas Discharge of Carbon Monoxide in Mining Extra-Thick Coal Seam of Datong Mining Area

Ma¹,

Du

²

2021

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In order to reveal the evolution law of gas discharge of carbon monoxide in mining an extra-thick coal seam of the Datong mining area by the numerical simulation and field monitoring test, the 8202 working face and 8309 working face in the Tongxin coal mine are chosen as the test sites. The results show that the seepage flow of carbon monoxide gas reaches 1.854 × 10 − 8 m 3 / s in the #1 fracture after the #3 key stratum in the far field breaks in the 8202 working face, the seepage flow of carbon monoxide gas reaches 1.307 × 10 − 7 m 3 / s in the #2 fracture, the seepage flow of carbon monoxide gas reaches 4.276 × 10 − 7 m 3 / s in the #3 fracture, the seepage flow of carbon monoxide gas reaches 4.192 × 10 − 7 m 3 / s in the #4 fracture, and the seepage flow of carbon monoxide gas reaches 1.623 × 10 − 7 m 3 / s in the #5 fracture. The initial caving of the #3 key stratum in the far field occurs and collapses to the gob, when the working face in the #3-5 coal seam advances to 180 m, and the voussoir beam forms in the #3 key stratum. Besides, a shower shape was formed by the seepage flow of carbon monoxide gas, and the maximum flow in the working face reaches 4.562 × 10 − 4 m 3 / s . When the 8309 working face advances from 521.2 m to 556.4 m, the air pressure at the working face gradually rises and reaches the maximum magnitude and then begins to decrease; when the working face advances to 556.4 m, the air pressure at the working face reaches the maximum magnitude of 91.35 kPa. The gas discharge disaster of carbon monoxide in mining the extra-thick coal seam of the Datong mining area is effectively controlled by the dynamic balance multipoint control technology. The research results can be treated as an important theoretical basis for the prevention and treatment for carbon monoxide discharge disaster in mining the extra-thick coal seam of the Datong mining area.

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Evolution Mechanism of Water-Conducting Channel of Collapse Column in Karst Mining Area of Southwest China

Cited by 23 publications

References 15 publications

Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

Disastrous Mechanism and Concentration Distribution of Gas Migration in Fully Mechanized Caving Stope in Wuyang Coal Mine

An Experimental Study on the Particle Size and Shape Distribution of Coal Drill Cuttings by Dynamic Image Analysis

Evolution Law of Gas Discharge of Carbon Monoxide in Mining Extra-Thick Coal Seam of Datong Mining Area

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