Influence of Basicity and TiO₂ Content on the Precipitation Behavior of the Ti-bearing Blast Furnace Slags

Abstract

The present paper investigated the influence of basicity and TiO₂ content on the crystallization behavior of the Ti-bearing blast furnace slag (Ti–BF slag). Single Hot Thermocouple Technique (SHTT) was applied to construct the Time-Temperature-Transformation (TTT) diagrams. Scanning Electron Microscope equipped with Energy-Dispersive X-ray spectroscope (SEM-EDX) and X-Ray Diffraction (XRD) were employed to observe the morphology and determine the crystalline phase of the Ti-enriched crystals. It was found that rutile was formed as the Ti-enriched phase when the basicity of the sample was lower than 0.6, and perovskite appeared as the Ti-enriched phase with an increasing basicity to 1.0. It was also noticed that the addition of TiO₂ could decrease the incubation time in the TTT diagram of the samples. The kinetics of the formation of Ti-enriched crystals, rutile and perovskite, was studied, and the mechanism of crystallization and growth was further discussed. The results indicated that the crystallization of rutile was one-dimensional interface-controlled growth, and the nucleation rate varied with the holding time at different TiO₂ content. While the precipitation behavior of perovskite was three-dimensional diffusion-controlled growth, and its nucleation rate decreased with the holding time.