The article presents the experimental results of studying the effect of the most widely used additives and dopants (promising in terms of the environment) on the ignition delay of slurry fuels prepared on the basis of coal and oil processing wastes. We have studied the most common organic additives: vegetable oils (coconut, rapeseed, olive), forest fuels (fallen leaves and pine needle litter), wood components (oak bark, sawdust, charcoal), plant wastes (algae, sunflower wastes, straw), glycerol, turpentine, ethanol, chalk, cardboard, and motor fire pyrolysis residue. The main components of slurry fuels were coal processing wastes (filter cakes of coking coal), water and used turbine oil. We have performed a comparative analysis of ignition delay times and threshold (minimum) ignition temperatures. Maximum ignition temperatures of slurry fuels have been studied as well. The experiments involved fuel droplets with a size (radius) of 1 mm. The combustion temperatures varied within the range of 700-900 degrees C. It is reasonable to add 10-20 wt% of filter cakes to use large volumes of the accumulated coal processing wastes and retain rheological and energy performance indicators of the slurry. It was established that the use of rapeseed and coconut oils, charcoal, carbonaceous residue of motor fire pyrolysis, straw, sunflower wastes and turpentine can most effectively decrease the ignition delay and minimum ignition temperature of the slurry fuel.