Preparation of ultralow-oxygen titanium by direct reduction of TiO2
(1. Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, China;
2. National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China;
3. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China;
4. State Key Laboratory of Complex Non-ferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, China)
2. National Engineering Research Center of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China;
3. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China;
4. State Key Laboratory of Complex Non-ferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, China)
Abstract: A new method for the preparation of low oxygen titanium was proposed by the direct reduction of TiO2 with Mg produced by MgCl2-KCl-YCl3 molten salt electrolysis. The Mg-Ti-O phase diagram indicates that it is feasible to reduce TiO2 using Mg, and the φ-pO2- diagrams indicate that deep deoxidation of titanium in molten MgCl2-YCl3 is also feasible. The experimental study on the reduction of TiO2 was carried out in MgCl2-YCl3 and MgCl2-YCl3-KCl molten salts. The results showed that the O2- from the reduction and deoxygenation was removed using YOCl precipitation and COx gas production and TiO2 can be reduced to titanium peroxide (Ti6O) by electrochemical reduction at 1073-1173 K and 2.5-3.1 V. The high-oxygen titanium was electrochemically deoxidized in the molten salt of MgCl2-YCl3 at a temperature of 1173 K at different voltages. Moreover, it was observed that it is possible to reduce the high oxygen content of titanium from 1200×10-6 to less than 100×10-6 oxygen.
Key words: titanium dioxide; electrochemistry; magnesium reduction; deoxidation; ultralow-oxygen Ti; rare earth metals