Abstract: In order to study flame characteristics of combined explosion of coal dust carried by high pressure airflow and induced deposited coal powder, experiments were carried out on samples of the lignite, long flame coal, non-stick coal and gas coal by using a horizontal glass tube test device. Effects of the mass of deposited coal powder(m), the particle size of deposited coal powder(r) and the mass of CaCO\-3 mixed with deposited coal powder(k) on flame characteristics of combined explosion, the longest distance of flame propagation(l) and the duration of flame(t)were studied. Study result shows that with the increase of m in the range of 0-4.5 g, l and t of four kinds of coal dust increase first and then decrease, after l and t reach the local maximum value, they begin to decrease, that for these four kinds of coal dust, l decreases slowly with the increase of r, that the maximum values of l are 106, 73, 37 and 22 cm respectively. t\-3 and t\-4 increase with the increase of r, even when r> 40 μm and that when k=6 g, the inhibitory efficiency of lignite and long flame coal are 62.5% and 79.7% respectively, while the non-stick coal and the gas coal are no longer explosive.

Key words: coal dust explosion, high pressure air, cumulated coal powder, flame characteristic, CaCO₃ powder