A deep insight into the dynamic crystallization of coal slags and the correlation with melt microstructure

In liquid discharging furnace, crystallization can occur in slags during the cooling process. The presence of crystal changes the structure, flow, heat transfer, especially the viscosity with a sharp increase. A deep understanding of the crystal kinetics is significant to optimize the flow of liquid slag. Crystal kinetics varies significantly with different slags due to the complexity and variability of the multi components in slags. In this paper, a high-temperature microscopy with high-resolution is used to clearly observe the in situ precipitation of different crystals and the kinetic parameters of different crystals are analyzed. Microscopic structure analysis of both the melt and the precipitated crystal shows that the proportion of basic oxygen structure and the diffusion coefficient of the basic cation in the melt have a direct correlation with the growth of crystal. A structural parameter St of the melt is developed, which has a positive correlation with the crystal growth rate. This is a new discovery in bridging the gap between the melt and precipitated crystals and it provides a way to control the crystal growth during slag cooling.