Crystallisation behaviour of the iron oxide-devoid BOF slag with adding SiO2

Abstract

The current research attempted to investigate the crystallisation mechanism of iron oxide-devoid basic oxygen furnace (BOF) slag with adding SiO2. First, the glass sample was prepared by adding 29 wt-% of SiO2 to BOF slag, followed by eliminating iron oxide by reduction process. Non-isothermal DSC analysis together with confocal laser microscopy, XRD and EPMA mappings were carried out to observe the crystallisation process. The glass sample showed that the crystallisation process started from the surface where the main phases were identified to be akermanite, merwinite and wollastonite. In addition, the crystallisation process was affected by the nucleation temperature which was decided by the heating rate because of the difference in the nucleation rate between wollastonite and Mg-rich phases. The current results could be used to propose the feasibility of utilising BOF slag as glass-ceramics by chemical modification with heat treatment, which controls the crystallisation behaviour.