Numerical Analysis On The Potential Danger Zone Of Compound Hazard In Gob Under Mining Condition

For years, the methane (CH4) explosion accidents initiated by spontaneous coal combustion took hundreds of lives and destroyed billion possessions in the process of mining. This work developed a fully coupled model involving complex interactions between oxygen transport and airflow, coal spontaneous combustion, CH4 emission and migration. The aim was to analyze the potential danger zone of combined hazard posed by spontaneous coal combustion and CH4 build-up in mine. Unlike traditional fixed mesh that the working face and gob are fixedness, a moving mesh method was incorporated in the model to perform the dynamic gob as the advancing of working face. The moving mesh is modified by the algorithm of Laplace smoothing to avoid mesh distortion and advance the mesh quality. The dynamic distribution characteristics of the porosity, oxygen and CH4 concentration in the gob under mining condition were determined using numerical simulations. According to the theory of the compound hazard, the highest degree of compound hazard zone is identified. The results show that the zone representing the highest degree of compound hazard is located mainly in the middle of the strike directions of the working face, as well as a small part of it on the return airway side and closer to the working face. It was analyzed that the variations in location of potential danger zone under different ventilation flux, the advancing rate of the working face and the attenuation coefficient of CH4 release. Meanwhile, the governance methods for the compound hazard in the gob have been further discussed. This research can provide a guidance on the prediction and control of compound hazard represented by spontaneous coal combustion and methane emission, thus ensuring the safety production. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.