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.

煤矸石（coal gangue, CG）与麦秆（wheat straw, WS）等生物质废弃物的协同燃烧，为废弃物资源化利用与污染物减排提供了可持续路径。然而，目前针对掺混麦秆的煤矸石燃烧特性的研究仍不够充分。本研究采用热重分析仪（thermogravimetric analyzer, TGA），探究了煤矸石、麦秆及其五种不同配比混合物的协同燃烧行为。研究结果表明，掺入麦秆可显著降低煤矸石的着火温度与燃尽温度：纯煤矸石的着火温度与燃尽温度分别为474.4℃与770.2℃，而煤矸石-麦秆掺混物的着火温度降至255.6~267.9℃，燃尽温度降至608.9~710.5℃。在协同燃烧过程中，200~600℃区间存在显著的协同交互作用。动力学分析显示，掺入麦秆可大幅降低掺混物的表观活化能，纯煤矸石的表观活化能为75.41 kJ·mol⁻¹，而掺混20%麦秆的样品表观活化能降至34.14 kJ·mol⁻¹。诸如降低着火与燃尽温度、降低表观活化能等研究结果表明，煤矸石-麦秆协同燃烧可显著优化燃烧性能。因此，本研究深入阐明了煤矸石-麦秆混烧的热化学行为与动力学特性，可为工业场景中生物质-煤矸基废弃物的高效能源化最优利用提供理论支撑，同时也为废弃物能源化解决方案提供了可行路径。