Physicochemical properties of Chinese pulverized coal ash in relation to sulfur retention

The sulfur-retention properties, mineralogical compositions, porosities and surface morphologies of two Chinese high-calcium coal ashes are studied by XRD, SEM and porometer analysis. It is found that the active calcium (CaCO3 and CaO) content in Shenmu coal ash prepared at 800 °C is 22.40% and its sulfation product (CaSO4) content is 17.79%, which are both higher than those in Huangling coal ash (respectively, 4.48% and 4.92%). With an increase in furnace temperature from 800 to 1200 °C, the porosity parameters of these two coal ashes dramatically decrease due to their intensely melting and no calcium compounds are found.