Investigation on the potential hazard zone of gas explosion in the goaf under longwall top caving coal mining condition

ABSTRACT

In the present work, the potential hazards in mining goafs of multi-component gas explosions coupled with coal spontaneous combustion were systematically analyzed using both an experimental and numerical method. Programmed heating experiments show that many kinds of combustible gaseous products (CH₄, CO, C₂H₆ and C₂H₄) are released during the coal oxidation process under-simulated mining goaf conditions. The generation rate of each gas increases significantly after 200°C and reaches a peak value at about 400°C ~ 500°C. According to these results, a new model for the determination of the dynamic explosion limits of multi-component combustible gases in the goaf was proposed and validated to quantitatively determine the explosion hazard. Based on the dynamic explosion limits, the gases and temperature distributions in the goaf, the determination method for the potential explosion hazard in the goaf was proposed. As a typical working face in the Dafosi coal mine in China, the research results indicated that air leakages into the goaf influence the explosion hazard zones, but the hazard zones are always limited within the range of 50 m from the working face. To quantitatively analyze the risk of a gas explosion in the goaf zone, one index was defined to evaluate the explosion potential. With the mining forward, the risk index would be greatly increased after 30 days until to 50 days. After that, the risk in the deep zone would stabilize. The higher the amount of air, the higher explosion potential in the goaf.

KEYWORDS:

• Longwall goaf
• gas explosion
• coal spontaneous combustion
• hazard zone
• quantitative risk analysis

Acknowledgments

Financial supports from the National Natural Science Foundation of China (No. 51974303 and 52174214) and the Fundamental Research Funds for the Central Universities (No. 2020ZDPY0202, No. 2021GJZPY11, No. 2021YCPY0207).

Disclosure statement

The authors declare that there is no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No. 51974303 and No. 52174214]; Fundamental Research Funds for the Central Universities [No. 2020ZDPY0202, 2021GJZPY11 and 2021YCPY0207].