The clean production of low-oxygen titanium powder through molten salt electrolysis-magnesiothermic reduction (MSE-MR) of TiO2

Abstract

The Kroll process is the primary method for the producing of titanium sponge. However, it is related to complex procedures, low efficiency and a large amount of energy use. A new method to produce low-oxygen titanium powder using molten salt electrolysis-magnesiothermic reduction (MSE-MR) TiO₂ in MgCl₂-KCl-YCl₃ molten salt was proposed, aiming at improving production efficiency and reducing costs. TiO₂ and graphite were used as the cathode and anode, respectively. The metal Mg was deposited on the TiO₂ cathode by electrodeposition, so that O was removed from TiO₂ in the form of oxygen ions (O^2-) into the molten salt (2Mg (in flux) + TiO₂(s) = Ti(s) + 2O^2-(in flux) + 2Mg²⁺ (in flux)). O^2- is removed from the system by forming YOCl (O^2- (in flux) + Y³⁺ (in flux) + Cl^- (in flux) = YOCl (s)) in the molten salt and CO_x (x = 1, 2) (xO^2- + C (s) = CO_x (x = 1, 2) (g) + 2xe^-) on the anode. The activity of O^2- ($a_{O^{2-}}$) is notably decreased, which promotes Mg to remove O from titanium deeply. The results of the experiments show that titanium powder containing a content of oxygen of 360 ppm can be prepared by MSE-MR of TiO₂. The study describes a new method for producing low-oxygen titanium powder with an oxygen content of no more than 500 ppm. This approach offers several benefits, including a shorter processing time, reduced energy consumption, and lower emissions. It is expected to be applied in industry in the future and realize the clean production of Ti.