Crystallization characteristics prediction of coal slags based on SiO2–Al2O3–CaO–Fe2O3–MgO components

[Display omitted] •Samples with base–acid ratio R higher than 0.7 and Si/Al in the range 1–4 have high crystallization tendency.•The influence of R is more than that of Si/Al.•Crystallization temperature (Tcrys) has a linear relationship with liquidus temperature (Tliq). Crystallization inside the liquid slag can increase the viscosity, affecting flow down the wall which is associated with the temperature of critical viscosity (Tcv). Four groups of synthetic slags with different Si/Al, Si+Al, CaO, Fe2O3 ratios were sorted to study the crystallization characteristics including the crystallization tendency as well as crystallization temperature (Tcrys). Samples with base–acid ratio (R>0.7) and Si/Al in the range of 1–4 are liable to crystallize with obvious crystallization peak on DSC curve, and the influence of R is more than that of Si/Al. The crystallization temperature (Tcrys) is found to display a linear relationship with the liquidus temperature (Tliq). The deviation of real coal slag with synthetic slag is associated with the crystalline phases as well as the raw minerals present in the ash.