1. National Engineering Laboratory of Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, Yunnan, P. R. China
2. State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province, Kunming 650093, Yunnan, P. R. China
3. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China
4. State Key Laboratory of Vanadium and Titanium Comprehensive Utilization, Pangang Group Research Institute Co. Ltd, Panzhihua, 617000, China