Several grams of flammable dust mixed with air can cause a large explosion with severe consequences. In this study, dust mixtures explosion tests were performed in constant volume 0.02 m3 spherical vessels. 19 pressure-time curves were recorded. The effects of carbon amount in sample molecules on burning velocity were investigated for coal, biomass pellets, and ash-air dust mixtures. The most important results are the values of ash sample burning velocities. The results could be used for a hierarchical view of tested mixtures and for preventing and mitigating dust-air explosions in a given application.