Investigation on combustion performance and ash fusion characteristics of Zhundong coal co-combustion with coal gangue

Abstract

In this study, the combustion characteristics of Zhundong coal (ZC), coal gangue (CG) and the ZC-CG blends with 10, 20, 30, 40 and 50% CG were investigated using a thermogravimetric analysis (TGA). The ash fusion characteristic temperatures and mineral transformation behaviors during the ash melting process were also determined by analytical instruments. The results shows that the maximum weight loss rate of the ZC-CG blend increases at first and then decreases with the increase of CG adding percentage, reaching the maximum at 30% CG, while the corresponding peak temperature firstly decreases and then increases. Adding 30% CG into ZC is an optimal blending ratio for obtaining better combustion performance. The ash fusion temperatures of the ZC–CG ash including DT, ST, HT and FT generally increase firstly and then decrease with the increase of CG adding percentage from 10 to 50% CG, reaching the maximums at 40% CG. Ferric oxide (Fe2O3), calcium sulfate (CaSO4) and silicon dioxide (SiO2) are the main mineral compounds in the ZC-CG ash. As the adding percentage of CG into ZC increases, the microstructures of the ZC-CG ash become tighter and the particle sizes gradually turn bigger. The results obtained can be used for reference in a large pulverized Zhundong coal boiler burning a blended high ash coal for safety and economy.