四塩化チタンのマグネシウム熱還元における金属導電体を介した反応(LR-EMR)によるチタンの析出部位の制御

抄録

The Long Range Electronically Mediated Reaction (LR-EMR) has been tested for controlling the location of titanium deposit during magnesiothermic reduction of TiCl₄. An iron cathode tube immersed in molten salt was electrochemically connected with Mg-18 mol%Ag liquid alloy placed at the bottom of an anode crucible through an external circuit. When TiCl₄ was fed into the cathode tube at 1073 K, electrochemical reduction of TiCl₄ was confirmed by detecting current in the external circuit. This titanium reduction is attributed to LR-EMR because the concentration of silver is less than 50 mass ppm in the resultant titanium deposit, despite Mg-Ag alloy was used as the reductant. In this work, 70% of titanium deposit could be localized at the vicinity of cathode by adjusting the experimental conditions such as configuration of electrodes and molten salt compositions. Such localized deposition on the cathode tube was found to increase up to 80% by decreasing TiCl₄ feed rate. The conventional Kroll process is known to be difficult to control the location of titanium deposit during metallothermic reduction. However, the LR-EMR concept can bring about a significant breakthrough in this difficulty, as it has been demonstrated in this work. The present results also stimulate the development of semi-continuous titanium reduction process possible when applying LR-EMR.