A typical bituminous coal that could easily lead to slagging was divided into three ingredients with different density

i.e. low-density (<1.3 g·cm-3)

medium-density (1.3-1.6 g·cm-3) and high-density (>1.6 g·cm-3). Computer controlled scanning electron microscopy (CCSEM) was used to analyze and characterize the slagging minerals in the raw coal and three ingredients. The results showed that Na and K in inorganic minerals of the coal exist as aluminosilicate. Exterior (no bonding) pyrite and pyrrhotite with diameter larger than 22μm were mainly present in the high-density sample. The least proportion of unidentified materials in which there were the most particles containing 20%-90% of Fe component was involved in the high-density sample. The ratios of silicon to aluminum and basic to acidic oxides in bonding minerals were variation for different density samples. There was the highest basic to acidic oxides ratio in the low-density sample

suggesting highest slagging propensity. The ratios of silicon to aluminum and basic to acidic oxides were lower for the medium-density sample than for the raw coal.