Novel process for synthesizing fused mullite from titanium-rich medium/low grade or waste bauxite

Abstract

This paper introduces a novel process to efficiently utilize medium-/low-grade or waste bauxite. The medium-/low-grade or waste bauxite is usually rich in iron oxide (total iron oxide content≥8%) or titanium dioxide (titanium dioxide content≥5%). In addition, both iron oxide and titanium dioxide have higher contents than typical bauxite (total iron oxide + titanium dioxide contents≥20%). It is difficult to obtain mullite with excellent properties using the process of beneficiation and sintering synthesis. Based on different reduction temperatures of K2O, Na2O, FeOx, SiO2 and TiO2, the reduction of K2O, Na2O and FeOx was set as the reduction end point. While SiO2 start to be reduced, TiO2 was unstable under high temperature and low oxygen partial pressure. The reason for the final formation of Ti2O3 in the TiO2→TiO2-x transformation process was analysed, and the morphology of the multiphase material obtained from the Ti2O3–3Al2O3·2SiO2 solid solution was characterized. The reaction model was established.