The low reactivity of coal processing wastes (filter cakes), petroleum derivatives, oil sludge, oil-water emulsions, coal-water suspensions, as well as used fuel and industrial oils is the main barrier to their common use as main fuel on thermal power stations and a boiler plants. It leads to high energy consumption for heating the combustion chambers and subsequent firing. In this work, we suggest using sawdust as an additive to intensify the heating and ignition of coal water slurries containing petrochemicals (CWSP) prepared from coal and oil wastes. We show that adding even 10% sawdust lowers the threshold temperature of sustainable ignition by as much as 70-80 K. The more volatiles are in coal processing wastes, the more noticeable the contribution of sawdust to the intensity of CWSP ignition. The role of sawdust as an ignition intensifier is found to increase significantly with the rising CWSP droplet size and air temperature. Replacing the coal component (e.g., filter cake) of the CWSP composition by sawdust of the same mass leads to a negligible change in the calorific value of the fuel. At the same time, the anthropogenic emissions of nitrogen and sulfur oxides are reduced considerably. (C) 2017 Elsevier Ltd. All rights reserved.