CO emission regularity and its influencing factors in a fully mechanized caving face

Jia, Xinlei; Qi, Qingjie; Zhao, Youxin; Dong, Ziwen; Li, Xinghua

doi:10.1063/5.0050869

Cited by 4 publications

(4 citation statements)

References 16 publications

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“…Considering the convection-diffusion of gas in the goaf, the governing equations can be expressed as follows [10]:…”

Section: Gas Concentration In Goafmentioning

confidence: 99%

“…The roadway has large compression deformation, stress concentration, and frequent roof falling accidents, resulting in slow advancing speed of the working face, and the coal of the working face is broken, resulting in more loose coal being left in the goaf, which increases the risk of oxidation, heat storage, and SC of residual coal in the goaf, thereby initiating a catastrophe [8,9]. The problem of CO concentration exceeding the limit is becoming more and more prominent, even far exceeding the provisions of "Safety Regulations in Coal Mines of China", which will seriously threaten the life safety of front-line coal mine workers [10]. Accordingly, it is of significant importance to investigate SC in goaf originating from residual coal.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Spontaneous Combustion Zones and Index Gas Prediction System in Goaf of “Isolated Island” Working Face

Chai

2022

Fire

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Studies show that accurate division of spontaneous combustion (SC) zones in the goaf and the determination of the prediction system of the SC index are of great significance to prevent spontaneous and unwanted combustions in the goaf. Aiming at resolving the problem of coal SC in the goaf of an “isolated-island” fully mechanized caving face, a multiphysics model coupled with gas flow field and gas concentration field was established in the present study. Taking the 8824 working face of Nanzhuang coal mine as the research object and the oxygen concentration as the division index, coal SC was simulated in the goaf. The obtained results show that the ranges of heat dissipation zone, oxidation zone, and the asphyxia zone on the air inlet side are around 0–107 m, 107–239 m, and beyond 239 m, respectively. Moreover, the ranges of the three zones on the return air side are 0–13 m, 13–189 m, and beyond 189 m, respectively. The ranges of the three zones in the middle of goaf are 0–52 m, 52–213 m, and beyond 213 m, respectively. The performed analyses demonstrate that the obtained simulation results are consistent with the experimental data. Meanwhile, the coal programmed temperature rise experiment was carried out to improve the prediction index gas system of SC. It was found that CO and C2H4 can be used as early warning indices of SC in the goaf, while C2H6, C3H8, and C2H4/C2H6 are auxiliary indices to master the coal SC.

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“…Considering the convection-diffusion of gas in the goaf, the governing equations can be expressed as follows [10]:…”

Section: Gas Concentration In Goafmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of Spontaneous Combustion Zones and Index Gas Prediction System in Goaf of “Isolated Island” Working Face

Chai

2022

Fire

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“…Liu et al established a computational fluid dynamics model, simulating the percentage of CO concentration, and concluded that the upper corners and return airways are areas with higher CO concentrations throughout the coal mine. Jia studied the influencing factors of CO concentration in upper corners of working faces and analyzed the trend of CO concentration changes in upper corners.…”

Section: Introductionmentioning

confidence: 99%

Research on CO Migration Patterns in Shallowly Buried Coal Seam Composite Goafs

Mao,

Zhou,

Jia

et al. 2024

ACS Omega

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To address the issue of CO exceedance in the close-range composite goaf, this paper focuses on the composite goaf of the Shaping Mine as the research subject and investigated the migration dynamics of CO within shallowly buried composite goaf areas. Sulfur hexafluoride gas (SF 6 ) tracer experiments were conducted at the 13103 working face in Shaping Mine to assess surface fissures and air leakage, yielding insights into the distribution patterns of air leakage channels and facilitating the identification of critical areas for channel sealing. Programmed heating and oxidation experiments were conducted on coal seams 8 # and 13 # to determine the CO generation patterns during coal oxidation. The results show that higher concentrations of O 2 corresponded to elevated CO production at equivalent temperatures. Subsequent data analysis unveiled exponential relationships between the O 2 consumption rate and CO production rate within the goaf area, offering a theoretical framework for understanding CO migration patterns. Through numerical simulations, the study analyzed the CO migration patterns in the composite goaf area, observing downward diffusion of CO emanating from coal oxidation in the overlying goaf areas followed by dispersion toward the working face and roadways. Driven by airflow dynamics, CO accrued in the return air corner of the working face. Building upon these insights, comprehensive CO management strategies were implemented, resulting in sustained reductions of temperatures and CO concentrations to safe levels within the original high-temperature, high-concentration CO zones. Notably, CO concentrations at the return air corner of the working face continued to decline over the management period, reaching below 24 ppm within 10 to 15 days, highlighting the effectiveness of the management measures in ensuring safe underground production.

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“…Toxic and harmful gases such as CO generated by spontaneous combustion of coal seriously threaten the safe mining of underground working faces, and are a common problem in the process of coal mining in many countries 1 , 2 . China is the world’s largest coal producer, and the problem of exceeding safety limits of CO in the return corner of the working face is particularly serious 3 , 4 . With the depletion of coal resources in the eastern mining areas of China, China's coal mining center is gradually shifting to the western mining areas 5 , 6 .…”

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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CO emission regularity and its influencing factors in a fully mechanized caving face

Cited by 4 publications

References 16 publications

Investigation of Spontaneous Combustion Zones and Index Gas Prediction System in Goaf of “Isolated Island” Working Face

Investigation of Spontaneous Combustion Zones and Index Gas Prediction System in Goaf of “Isolated Island” Working Face

Research on CO Migration Patterns in Shallowly Buried Coal Seam Composite Goafs

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

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