Explosion energy of methane/deposited coal dust and inert effects of rock dust

In order to study the processes of lifting, dispersing and igniting of a dust layer behind the local gas explosion as well as their suppression, premixed methane local explosion igniting deposited coal/inert rock dust at the bottom of a tube are simulated. The two-phase combustion mechanism is obtained that the deposited dust is kicked up by the leading pressure wave, developing an uneven dust cloud filling in the tube, and then the gas flame ignites the dust cloud to form the composite flame. The rock dust lain on the tunnel ground has a significant suppression effect on the explosion overpressure, flame temperature and velocity of methane with coal dust. When the rock dust proportion in coal dust is 90%, the peak values of overpressure, flame temperature and flame velocity of the hybrid coal dust/rock dust/methane explosion are 0.6, 0.78 and 0.55 times of those of coal dust/methane explosion, respectively. The rock dust with the particles of smaller size has a remarkable suppression effect on explosion flame. When the rock dust proportion in the coal dust is 70%, the peak explosion overpressure and the flame velocity under suppression of the 12 µm rock dust are 10% and 11% lower than those of the 31 µm rock dust, respectively.