Investigation on co-combustion characteristics of Zhundong coal with coal slime: Combustion behavior, ash fusion and synergistic effect

Zhundong coal (ZD) has significant application potential due to its abundant resources, however, the problems such as slagging and fouling hinder its efficient utilization. ZD co-combustion with coal slime (CS) offers an effective solution to the issues. This study employed thermogravimetric analysis (TGA), ash melting point testing, XRD and SEM-EDS to investigate the combustion characteristics and ash melting behavior of ZD blended with 5, 10 and 30% CS. The results revealed that increasing the CS proportion significantly raised the ignition and burnout temperatures ZD, with the highest values observed at 30% CS. Additionally, a synergistic effect during co-combustion was identified, which notably enhanced the combustion performance of CS. The high SiO2 and Al2O3 content in CS elevated the ash melting point by reacting with alkali metals to form high-melting compounds, thereby reducing the formation of low-melting eutectics and mitigating slagging and fouling. To balance combustion stability and improve ash melting performance, a CS blending ratio of no more than 10% is recommended. This study provides valuable guidance for the safe and economical operation of a large-scale burning ZD power plant using CS as a low-cost supplementary fuel.