The Selection and Application of Gas Drainage Methods under the Influence of the Coal Spontaneous Combustion in the Gob: A Case Study in the Dalong Coal Mine, China

Yi Lu, Shiliang Shi, Qing Ye, Zhaojun Tian

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.


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