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Summary This study presents an analysis of the effects of repeated disturbance on the spontaneous combustion and oxidation properties of coal masses that are encountered in deep mining. Raw coal samples were tested under temperature‐programmed and repeated loading‐unloading (LU) conditions. In addition, the infrared (IR) spectra of the coal samples subjected to repeated LU cycles (LU coal samples) were analyzed using OMNIC IR analysis software. The results show the following. The LU coal samples were more prone to oxidation than the original coal sample. As the number of LU cycles increased, the degree of oxidation of the coal gradually increased.

Abstract:To safely mine coal, engineers must prevent gas combustion and explosions, as well as seek feasible and reasonable techniques to control for these types of incidents. This paper analyzes the causes and characteristics of methane combustion and explosions. Water mist is proposed to prevent and control methane combustion in an underground confined space. We constructed an experiment platform to investigate the suppression of methane combustion using water mist for different conditions. The experimental results showed that water mist is highly effective for methane flame inhibition. The flame was extinguished with water mist endothermic cooling. However, the annular regions of water vapor around the fire played a vital role in flame extinction. Water from the evaporating mist replaces the oxygen available to the fuel. Additionally, the time required for fuel ignition is prolonged. For these reasons, the water particle action to flame surface is reinforced and the fuel's reaction with air is delayed. As a result, flame stretching and disturbances occur, which serve to extinguish the flame. Engineering application tests were carried out in the goaf, drill hole and upper-corner to investigate the prevention and control of methane gas combustion, with the results showing a good application effect.

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