Here we consider the task of studying the flame burning of low-grade coals and their significantly ballasted waste with a low volatile yield and reactivity. It is shown that when reducing the quality of coal fuel, it is advisable to use two-step combustion methods with preliminary mechanochemical activation, which allows start-up of the boiler from a cold state without application of auxiliary fuels. The methods of mechanochemical activation have proven to be effective technologies for start-up of the boiler and maintaining the combustion of coals of different quality and technical composition. The developed technologies allow approaching the full-scale experimental-industrial implementation at thermal power plants. The two-stage system allows significant reduction in the cost of preparing micro-ground coal and number of start-up of the burners, since fuel from a standard boiler mill is supplied to the second stage with a different ratios, depending on the reaction properties of the fuel, i.e. it is possible to increase the power of a of start-up of the burner several times as compared with single-stage combustion.