Numerical Assessment of the Influences of the Coal Spontaneous Combustion on Gas Drainage Methods Optimization and Its Application

ABSTRACT

Gas and spontaneous combustion of coal have seriously threatened the production safety and efficiency during the process of mining. Gas drainage can reduce the risk of gas while it may intensify the self-ignition of coal. In order to study the certain relationship between these two issues, the south 906 working face of Dalong Coal Mine was taken into research. The physical geometrical and mathematical model was established. Numerical investigation based on Fluent was conducted to identify the gas concentration distribution and air leakage field under four different gas drainage methods, such as high drill holes drainage (HDHE), buried pipe drainage (BPE), adjacent roadway drainage (ARE), and tail roadway drainage (TRE). The simulation results show that all these four gas drainage methods are able to control the gas concentration in the air return corner, so as not to exceed the certain limit (1%). However, these methods have also enlarged the area of spontaneous combustion zone with 1.11, 1.30, 1.61, and 2.10 times, respectively. According to the comprehensive analysis on simulation results, HDHE has the minimal influence under the same gas drainage amount. This gas drainage method was then applied in the aforementioned working face. The follow-up monitoring data proved our research results, with CO concentration in the drainage pipes always keeping lower than 0.0024% and gas concentration in the air return corner maintaining no more than 0.70%. The study provides significant references for managing the gob where exists symbiosis disaster of gas explosion and spontaneous combustion of coal.

KEYWORDS:

• Gas disasters
• Gas drainage method
• Air leakage field
• Spontaneous combustion of coal

Conflicts of Interest

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51974119, 51774135, 51974120 and 51874131]; China Postdoctoral Science Foundation [2017M612558 and 2018T110831].