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 degrees C and 770.2 degrees C, respectively, while CG/WS blends show reduced temperatures of 255.6-267.9 degrees C for ignition and 608.9-710.5 degrees C for burnout. A pronounced synergistic interaction occurs mainly between 200 and 600 degrees 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.