This study investigates the ignition, combustion, and thermal decomposition processes of composite fuels produced from pine sawdust and anthracite coal through mechanochemical activation. The research aims to optimize the co-combustion of low-reactivity coal and biomass by analyzing the nonadditive effects of composite formation on fuel reactivity and combustion efficiency. Experimental methods include synchronous thermal analysis (STA) to evaluate thermal decomposition stages, ignition delay measurements in a vertical tube furnace, and flare combustion tests in a 50 kW semi-industrial burner to assess practical performance. The results show that composite fuels outperform physical mixtures in combustion characteristics. Thermogravimetric analysis reveals a threestage decomposition process for composites, with overlapping stages of volatile release, coke residue oxidation, and anthracite carbon combustion. The composite achieves stable torch combustion, while the equivalent mixture fails to stabilize. Ignition delay times for composites are significantly lower than for mixtures or pure components, with the optimal ratio reducing ignition time by 20-30%. Mechanochemical activation generates paramagnetic centers on particle surfaces, accelerating ignition through radical-initiated reactions. The findings highlight the superiority of composite fuels in improving combustion efficiency, particularly for low-reactivity coals like anthracite. This study lays the groundwork for developing advanced solid biofuels applicable to co-firing systems, advancing sustainable energy solutions and biomass waste utilization.