Preparation of TiO2 from ilmenite using sulfuric acid decomposition of the titania residue combined with separation of Fe3+ with EDTA during hydrolysis

A new process of “mechanical activation–hydrochloric acid leaching–concentrated sulfuric acid decomposition–water leaching–separation of Fe3+ with EDTA during hydrolysis” was proposed to prepare high-purity TiO2 from Panzhihua ilmenite. The hydrolyzed titania residue prepared from mechanically activated Panzhihua ilmenite leached by hydrochloric acid was decomposed by concentrated sulfuric acid and subsequently dissolved in water yielding titanium sulfate solution. In order to improve the purity of the precursor during the hydrolysis of TiO2+, EDTA was investigated as an additive to restrain the hydrolysis of Fe3+. The effects of sulfuric acid concentration, acid-to-titania residue mass ratio in the process of acid digestion and the significant effects of water leaching time, leaching temperature and liquid-to-solid mass ratios on the recovery of Ti from the residue were studied in this paper. The recovery of Ti was above 98% under optimal conditions. Well-crystallized anatase TiO2 and rutile TiO2 could be obtained through calcining at different temperatures and no impurity can be detected by EDS in titanium dioxide. The results demonstrated that the process is inexpensive, environment friendly and promising in preparing high-purity TiO2 from ilmenite with a high content of gangues like Panzhihua ilmenite.