Laboratory study of the effect of coal dust in a blend of coal and methane

In this study, the effect of coal dust particle size on the intensity of coal dust explosion was investigated using an explosion test in a 2-liter chamber. Samples of coal have been collected from various coal mines in the country and they are used for coal dust preparation. To determine the index of explosion capability (KST), the distribution of the explosion intensity of each sample should be evaluated by measuring the maximum pressure (Pmax) and the maximum explosion pressure rise rate (dp/dtmax) in different experiments. Coal dust particles at constant concentrations and different sizes (149µm, 125µm, 105µm, 74µm, 63µm, 53µm, 44µm, 37µm) were evaluated. The results of the sieving analysis show that almost all samples of the prepared coal dust have a minimum optimum explosive concentration (250 g/m3 ). In this analysis, all tests were carried out at 1.5 bar and the initial temperature was 25 °C. According to the results, coal dust particles with dimensions of 44 and 37 microns have higher explosive index than other dimensions. Therefore, both parameters of maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate (dp/dtmax) show an increasing trend with decreasing particle size. Also an increasing concentration of coal dust shows an increasing trend at the first and then a decrease in the intensity of the explosion. The presence of small coal particles increases the effective level, thus increasing the explosion rate and the rate of instability, which accelerates the process of coal dust explosion. Therefore, according to the results obtained in the process of checking coal dust explosion, in addition to the inherent characteristics of coal dust, particle size coal dust should also be taken into account. The results obtained in this mechanism are useful not only in the research and development of knowledge of coal dust blasting processes, but also in taking the necessary measures to prevent the explosion of coal dust in coal mines.