Transition of TiO_2 in TiO_2/Vermiculite Nanocomposites

The TiO2/vermiculite composites were prepared by in-situ hydrolyzing reaction and in-situ dehydrating reaction of tetrabutyl titanate-hexadecyl trimethyl ammonium bromide intercalated vermiculite. The structural phase transition of TiO2 in TiO2/vermiculite composites calcined at different temperatures was characterized by using XRD and Raman. The results show that at calcination temperature of 800℃ appeared the anatase phase of TiO2 in TiO2/vermiculite nanocomposites, while pure TiO2 is all converted to rutile at the same temperature. The average crystal size of TiO2 in TiO2/vermiculite nanocomposites and pure TiO2 both increase with the calcination temperature. The average grain size of TiO2 in TiO2/vermiculite nanocomposites is less than that of pure TiO2 at the same calcination temperature. The results also show that the silicon-oxygen structure in layered vermiculite structure can effectively depress the phase transformation from anatase to rutile, thus enhancing the transition temperature and inhibitting the growth of anatase crystals.

Chemical and mineralogical characterizations of high Ti-bearing blast furnace slag in Panzhihua region were investigated and the technical approach "recycling Fe by magnetic separation-extracting Al by sulfation roasting and water leaching-extracting Ti by acidolysis" was proposed for recycling the valuable elements from the special mineral resources. The results show that the most valuable metal is Ti (20.46% TiO2, mass fraction). Other metals, such as Al, Mg and Fe can also be seen as valuable metal to be recovered. Minerals such as perovskite, diopside and spinel are disseminated in the slag. Metallic iron usually filling in the diopside, the Ti element in the slag is distributed widely in many types of mineral phases and Ti component enriches mainly in perovskite phase. It is highly euhedral and mostly disseminates in the diopside, usually presents an equiaxed or irregular granular shape, particles are commonly tiny, in the range of 10–20 μm.