Precipitation and growth mechanism of perovskite phase in molten Ti-bearing blast furnace slag under dynamic oxidation condition

Dynamic oxidation is not only in favor of that Ti components in molten Ti-bearing blast furnace slag enrich into the design phase (perovskite), but also promotes the coarsening and growth of perovskite phase. The enrichment and settlement of coarsened perovskite are carried out under the action of gravity. The nucleation rate and the crystal growth rate of perovskite phase in molten Ti-bearing blast furnace slag under dynamic oxidation condition were studied by using the kinetic equation of glass formation. The results show that low valence titanium (Ti²⁺) and (Ti³⁺) are oxidized to (Ti⁴⁺) under dynamic oxidation condition by blowing oxygen, which can promote the precipitation of perovskite and increase the crystal growth rate. When continuing to blow oxygen, the oxidizing time would be too long, TiC and TiN particles decrease and finally almost vanish, the slag viscosity decreases, and the crystallization of perovskite phase transforms from heterogeneous nucleation into homogeneous nucleation. As a result, the precipitation temperature decreases and the precipitation temperature range shortens, which restrain the coarsening and growth of perovskite.