The interaction mechanism between molten SiO2-Al2O3-CaO slag and graphite with different crystal orientations: Experiment and Ab initio molecular dynamics simulation

Abstract

An in-depth understanding of the interaction mechanism between slag and graphite is essential for guiding the high-efficiency utilization of natural carbonaceous materials. Such knowledge is, however, presently very limited to guide. Experiments and extensive ab initio molecular dynamics simulation studies were carried out on interactions of CaO-Al2O3-SiO2 slags and graphite with different crystal orientations at 2000K. The slag showed a robust chemical interaction with the graphite prism plane; the interaction becomes more robust with the increased CaO/SiO2 ratio. However, in the basal model, the interaction is weak and of van der Waals nature; the effect of CaO/SiO2 on the interaction is also reversed. In the microstructure analysis, the migration of Si, Al, and O atoms and the existence of active sites on the graphite are the main reasons for the interfacial interaction, which promotes the formation of new tetrahedral structures at the interface. The initial interface structures were SiO3C, AlO3C, and AlO2C2, and their stability is more than SiO4 or AlO4 tetrahedra.