Challenges in the Development of Electrochemical Reduction of TiO2 to Titanium Metal

Electrochemical reduction of metal oxides to metal has been gaining attention world over due to inherent advantages of simplicity of the process, energy savings and minimal environmental burden compared to conventional extraction technologies. More importantly, for reactive metals like titanium, R&D efforts have been increasingly put in for exploring the process for cost- and energy-effective production of metal. The electrochemical reduction of TiO 2 essentially involves high-temperature (about 950 °C) cathodic treatment of the oxide granules/pre-forms in molten calcium chloride using graphite as anode. In the present work, the reduction of titanium dioxide to titanium metal has been extensively studied in different scales of operation. Among various process parameters, electrode potentials, DC voltage, bath temperature and current densities play a key role in the conversion of oxide to metal. Based on the experimental observations on variation of DC current, electrode potentials and CO/CO 2 content in the vent gases, attempts have been made to develop improved understanding on mechanism of conversion and kinetic aspects of the reduction process. During scaling up of the reduction process, many process-related problems and technological issues such as incomplete conversion, characterization of the product and design of the cell with required electrode configuration, solid precipitates between electrodes and carbon fine deposition over the melt are encountered. This paper brings out various challenges that are being tackled in scaling up of the process along with important process observations that influence bulk kinetics of the process.