Study on Multi-field Evolution and Influencing Factors of Coal Spontaneous Combustion in Goaf

Zheng, Yuannan; Li, Qingzhao; Zhu, Pengfei; Li, Xiaowen; Zhang, Guiyun; Ma, Xu; Zhao, Yang

doi:10.1080/00102202.2021.1947262

Cited by 42 publications

(23 citation statements)

References 34 publications

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“…The oxygen in the goaf reacts with the residual coal by oxidation and exothermic reaction, and the heat exchange occurs between the coal rock exothermic reaction and the gas in the goaf, so the heat transfer conservation equation of the solid phase and gas phase in the goaf can be expressed as 27,28…”

Section: Energy Conservation Equationmentioning

confidence: 99%

Study on Multifield Migration and Evolution Law of the Oxidation Heating Process of Coal Spontaneous Combustion in Dynamic Goaf

Lei

Jiang

Bao³

et al. 2023

ACS Omega

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To study the dynamic evolution law of the oxidation heating process of coal spontaneous combustion in the goaf during the advancing process of the working face, a dynamic model of oxidation heating of coal spontaneous combustion in the goaf was established on the basis of deformed geometry. Through numerical simulation research, the evolution and migration laws of seepage field, oxygen concentration field, temperature field, and high-temperature area of coal spontaneous combustion in the goaf during the advancement of the working face was obtained. The results indicate that the distribution of the bulking coefficient, porosity, and permeability of the falling coal and rock mass in the goaf is nonuniform. They are relatively large in the area near the working face and the inlet and return airway and remain relatively unchanged with the advancement of the working face, but they are constantly decreasing in the location of the gob in the middle and deep. The oxygen concentration in the goaf presents an asymmetrical distribution. The oxygen concentration distribution area on the inlet side is wider than that on the return air side. At the same depth of the goaf, the oxygen concentration gradually decreases from the inlet side to the return air side; after the advancement distance exceeds 200 m, the air leakage in the goaf basically disappears, and the oxygen concentration decreases to zero. The high-temperature area of coal spontaneous combustion oxidation in the goaf was mainly concentrated on the air inlet side and extended toward the return air side. The advancing speed has a significant effect on the oxidation heating process of coal spontaneous combustion in the dynamic goaf. Under the same propulsion distance, when the advancing speed is 6 m/day, the highest temperature in the goaf is about 40 °C, and when the advancing speed is 2 m/day, the highest temperature in the goaf is as high as 120 °C. The smaller the advancing speed, the higher the heating rate of the goaf and the closer the high-temperature area to the working surface. The higher the advancing speed, the lower the temperature of the high-temperature point of the goaf and the greater the depth of the high-temperature point of the high temperature area; when the advancing speed is 2 m/day, the highest temperature point in the goaf is 70 m away from the working face, whereas when the advancing speed is 6 m/day, it reaches 174.6 m.

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Section: Energy Conservation Equationmentioning

confidence: 99%

Study on Multifield Migration and Evolution Law of the Oxidation Heating Process of Coal Spontaneous Combustion in Dynamic Goaf

Lei

Jiang

Bao³

et al. 2023

ACS Omega

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“…Under the negative pressure ventilation conditions of the mine, the surface air leakage enters the goaf through the cracks, which provides sufficient oxygen supply conditions for the oxidation of residual coal in the goaf, and increases the generation of CO from the oxidation of residual coal 13 . At the same time, the air leakage affects the migration of CO in the goaf, which can easily lead to the accumulation of CO in the return corner or even exceed the safety limits, which poses a serious threat to safety and health of workers 14 – 16 .…”

Section: Introductionmentioning

confidence: 99%

Study on generation, migration and accumulation of CO in the mining goaf of shallow-buried close distance coal seam group

Chen

et al. 2022

Sci Rep

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There is complex air leakage in the mining of shallow buried close distance coal seam group, which affects the generation and migration of CO in the goaf, and easily leads to exceeding safety limits of CO in the return corner of the working face, which threatens the safety of underground production. To examine this problem, taking Lijiahao Coal Mine as an example, this study analyses the generation law of CO gas, the distribution law of overburden fractures, the characteristics of air leakage in the goaf, the sources of CO in the return corner, and the migration and accumulation law of CO in the goaf under multi-source air leakage in the mining of shallow buried close distance coal seam group through experiment tests, numerical simulations, observations and theoretical analyses. The results indicated that there is an exponential growth relationship between the CO generation rate and the coal temperature, and the critical temperature for rapid oxidation of coal samples is between 70 and 80 °C. The 31,115 working face has complicated air leakage from the working face and ground surface and the goaf of this coal seam. The surface air converges to the return corner through the mining fissure of overburden and 2–2 coal goaf, and the air leakage of the working face flows out from the return roadway through the goaf. The gas leakage in the overlying goaf and the oxidation of residual coal are the main sources of CO in the return corner. The CO generated during the coal mining process and the CO generated by the trackless rubber-tired vehicle operation will increase the CO concentration in the return corner to varying degrees. Under the effect of multi-source air leakage, CO from the overlying goaf and the residual coal in the goaf of this coal seam are migrated to the air return side of the goaf, resulting in the accumulation of CO in the return corner, and both of them have a linear positive correlation with the CO concentration in the return corner. The results of the study have scientific guidance for the control of air leakage and the prevention of CO excess in the goaf.

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“…Some scholars believe that the change of the ventilation mode will lead to the change of gas distribution in the gob through numerical simulations ,− and field measurements compared with U-type, U + L-type, Y-type, and Y + L-type ventilations, and through a comparison, they found that Y-type and U + L-type ventilations can effectively manage the upper corner gas over limit problem; at the same time, the change of the ventilation mode brings some problems; Y-type ventilation leakage compared with the U-type ventilation leakage area is larger; the gob oxidation warming zone range is wider; as the U + L digging volume increases, it will cause workload increase and mining relationship imbalance. Zheng et al − conducted similar simulation experiments through a self-built experimental platform to simulate the effect of the presence or absence of a heat source on the gas concentration in the gob and concluded that the magnitude of gas concentration variation in the gob decreases with increasing distance from the high-temperature point vertically based on the measured point data, proving that temperature is the main factor affecting the change in gas concentration and gas accumulation in the gob.…”

Section: Introductionmentioning

confidence: 99%

Gas Emergence Characteristics of the Upper Corner on the 215101 Mining Working Face of the Yue Nan Coal Mine

et al. 2022

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To prevent the gas over limit in the upper corner of the 215101 working face of the Yue Nan coal mine, a numerical simulation method was used to analyze the gas concentration in the upper corner of the working face at different air intake volumes and mining velocities. The research results show that the gas concentration in the upper corner is 0.78, 0.52, 0.39, and 0.32% when the wind speed of the intake airflow roadway is 1, 1.5, 2, and 2.5 m/s, respectively, and an optimal wind speed of the intake airflow roadway is selected as 2 m/s. When the wind speed of the intake airflow roadway is 2 m/s, the working face mining velocity is 1, 2, 3, and 4 m/d, and the gas concentration in the upper corner is 0.27, 0.39, 0.58, and 0.83%, respectively, and an optimal working face mining velocity of 3 m/d is selected. Under the optimal mining conditions, the working face wind leakage area is divided, with 0∼30 m of the working face as the main leakage area and 150–180 m as the wind flow compensation area. According to the wind speed in the gob, the wind flow disturbance area is divided, the gob 0–50 m is the wind flow intense disturbance area, which is the main area of the upper corner gas source; the gob 50–62 m is the wind flow medium disturbance area, which is the secondary area of the upper corner gas source; the gob 62–75 m is the slight disturbance area, which has less influence on the upper corner gas concentration; the gob after 75 m is the wind flow undisturbed area, and the upper corner gas concentration is almost unaffected by it.

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Study on Multi-field Evolution and Influencing Factors of Coal Spontaneous Combustion in Goaf

Cited by 42 publications

References 34 publications

Study on Multifield Migration and Evolution Law of the Oxidation Heating Process of Coal Spontaneous Combustion in Dynamic Goaf

Study on Multifield Migration and Evolution Law of the Oxidation Heating Process of Coal Spontaneous Combustion in Dynamic Goaf

Study on generation, migration and accumulation of CO in the mining goaf of shallow-buried close distance coal seam group

Gas Emergence Characteristics of the Upper Corner on the 215101 Mining Working Face of the Yue Nan Coal Mine

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