Unlocking the synergy: Thermochemical behavior and kinetics in the co-combustion of coal gangue and wheat straw

Co-combustion of coal gangue (CG) and biowaste, such as wheat straw (WS), offers a sustainable approach to waste valorization and emissions reduction. However, the combustion characteristics of CG in the presence of WS have been insufficiently explored. This study investigates the co-combustion behavior of CG, WS, and their mixtures at five different ratios using a thermogravimetric analyzer (TGA). The results reveal that the addition of WS significantly lowers both the ignition and burnout temperatures of CG. Pure CG exhibits ignition and burnout temperatures of 474.4°C and 770.2°C, respectively, while CG/WS blends show reduced temperatures of 255.6–267.9°C for ignition and 608.9–710.5°C for burnout. A pronounced synergistic interaction occurs mainly between 200 and 600°C during the co-combustion process. Kinetic analysis demonstrates that WS addition substantially decreases the apparent activation energy of the blends, from 75.41 kJ mol−1 for CG to 34.14 kJ mol−1 for the blend with 20% WS. The findings such as the reduced ignition and burnout temperatures, and lower activation energy indicate that CG/WS co-combustion can significantly improve combustion behaviors. Hence, this study provides valuable insights into the thermochemical behavior and kinetics of CG/WS co-firing, promoting the optimal utilization of biomass-coal waste for efficient energy production in industrial applications while offering waste-to-energy solutions.