Minimum ignition temperature of carbonaceous dust clouds in air with CH4/H2/CO below the gas lower explosion limit

•The presence of small amount of CH4/H2/CO has different effects on different dusts.•A novel heterogeneous ignition mechanism model is proposed to interpret the ignition of hybrid anthracite coal-CxHy mixture.•CH4/CO has a negative effect of concentration on ignition temperature of bituminous coal dusts.•The ignition mechanism varies with the volatile matter content of carbonaceous dusts and the type of flammable gases.