The numerical simulation on the regularity of dust dispersion in whole-rock mechanized excavation face with different air-draft amount

Abstract

Abstract An experimental investigation was carried out on coal dust-inertant mixture explosions. Tests of explosion severity and flammability limit were conducted by using the Siwek 20 L vessel and influences of ignition energy, coal dust calorific value, coal dust concentration and inertant composition were taken into account. The increase of inerting results with ignition energy is followed by an approximate stabilization when ignition energy exceeds 5 kJ. The ignition energy region of 5-10 kJ is appropriate for inerting testing, whereas ignitors with energy lower than 5 kJ produce unrealistic inerting results. The inerting effectiveness of inertant increases with the reduction of coal dust calorific value. Coal dust concentrations near the stoichiometric concentration require the greatest amount of inertant to suppress explosions. As the coal dust concentration increases beyond the stoichiometric, the amount of inertant requirement is reduced. Due to the efficient decomposition and particular flame extinguishing mechanism, monoammonium phosphate represents more excellent inerting effectiveness than calcium carbonate.