Effect of SiO2 Content on the Enrichment of Perovskite in Ti-Bearing Blast Furnace Slag

Titanium-bearing blast furnace slag is rich in high-melting-point titanium-containing minerals including perovskite, melilite and spinel, which result in the loss of titanium resources and hinder the comprehensive utilization of such slag. On this basis, combined with process mineralogy theories, this study adopted multiple characterization methods, including a polarized light microscope with transmitted and reflected light, XRD and EPMA. These simulations reveal that the bulk SiO2 content dictates titanium distribution among the mineral phases, thereby laying a solid foundation for the subsequent experiments. Meanwhile, quantitative analyses were performed on the microstructure, mineral composition and perovskite grain size of the slag. The occurrence state and migration law of titanium in the slag were systematically investigated. The results show that the microstructure of titanium-bearing blast furnace slag presents a porphyritic structure at different SiO2 levels. Its main mineral phases include perovskite, pyroxene, spinel and glass. Titanium is predominantly hosted in perovskite, with small amounts distributed in the pyroxene, spinel and glass phases. Reducing the SiO2 content facilitates the formation and grain coarsening of perovskite and promotes the migration of titanium from pyroxene and glass into perovskite. When the SiO2 content is 20%, the perovskite content reaches 44.3%. Among them, the proportion of grains larger than 40 μm is 59.94%, and the distribution ratio of titanium in perovskite is 86.78%. Under the experimental conditions of this study, 20% SiO2 is the optimal level. These findings can provide a theoretical reference for the efficient separation and recovery of titanium from titanium-bearing blast furnace slag.