Influence of O2/CO2 combustion on interaction of Ca and Fe in Shenhua coal

Shenhua coal, with high concentration of Ca and Fe, was subjected to combustion in the drop tube furnace (DTF) in both air and O2/CO2 atmosphere. XRF, XRD and CCSEM were used to characterize elemental composition, mineralogy and element symbiotic properties of bulk ash. Oxy-fuel combustion promoted interaction of Fe and Ca with other minerals. However, the amount of Fe distributed in iron aluminosilicate (Fe-alsil), especially in Fe+Ca minerals increased. The same distribution tendency of Ca was observed. Further analysis found that Fe+Ca mineral in oxy-fuel combustion bulk ash had more serious slagging propensity (with Fe2O3/CaO mole ratios 0.5—3) than that in air combustion bulk ash.