Preparation of low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt

Abstract

The Kroll process is currently the only effective method in industry to produce sponge titanium with a low-oxygen concentration (500 ppm). However, it has several limitations, such as a long processing time, low efficiency, and high energy consumption, resulting in the high production cost of titanium. To reduce the production cost, a method to prepare low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt was designed. The thermodynamic calculation results showed that it was feasible to prepare titanium powder by the magnesiothermic reduction of TiO2 at 1073, 1173, and 1273 K. In addition, the deoxidation limits of Mg under Mg/MgCl2/YCl3/YOCl equilibrium were 3, 12, and 38 ppm at 1073, 1173, and 1273 K, respectively. The experimental results showed that titanium powder with a high oxygen concentration of approximately 10,000 ppm was obtained when the reduction was conducted in KCl–MgCl2 molten salt (i.e., the activity of YCl3 (aYCl3) was 0). Low-oxygen titanium powder was prepared with the addition of YCl3 in the molten salt and formed yttrium oxychloride (YOCl) (TiO2 (s) + 2Mg (l) + 2YCl3 (l) = Ti (s) + 2MgCl2 (l) + 2YOCl (s)). Moreover, at 1173 K, when the activity of YCl3 (aYCl3) was 1, titanium powder with an oxygen concentration as low as 150 ppm was obtained. Based on these results, a novel process for preparing low-oxygen titanium powder was designed. The proposed process is fast and highly efficient, and its future application in industry is anticipated.