Abstract: To understand and prevent the explosion accidents of coal dust, experiments were carried out by using a large-scale horizontal combustion tube. Influences of both particle size and volatile content of coal dust on the explosion overpressure were investigate. ABC powder, CaCO₃ rock dust powder and SiO₂ powder were taken as the suppressing agents. The effects of kind, concentration and particle size of suppressing agents on explosion suppression were studied. The experimental results show that the influences of coal dust particle size and volatile content on explosion overpressure gradually diminish with the increasing of coal dust concentration,that for coal dust explosion suppression, the effect order is ABC powder, SiO₂ and CaCO₃ powder,that for ABC powder, the smaller the average particle sizes are, the better the suppressing effects will be,and that only when the concentrations of suppressing agents are enough high, and more than 920 g/m³, can complete explosion suppression be achieved, otherwise, the explosion wave would newly develop through the explosion suppression zone.

Key words: coal dust explosions, dust particle size, overpressure, explosion suppression, tube