Phase equilibria and reaction pathways during TiCl4 reduction by magnesium and sodium involving electronically mediated reaction

The mechanism of titanium deposition has been investigated in the study on the electronically mediated reaction (EMR) during metallothermic reduction. The importance of EMR as well as its usefulness on the mechanism of titanium deposition was recognized by utilizing isothermal chemical potential diagrams for Ti-Mg-Cl and Ti-Na-Ci at 1073 K. Phase equilibria and reaction pathways in the Kroll or Hunter process were also considered. In the Kroll process, a long-range electronically mediated reaction (LR-EMR) in which the titanium deposit and the reaction container act as an electron conductor was found to be dominant, and this leads to the formation of sponge titanium. Both the electron and ion transfers in NaCl solutions are quite likely to occur in the course of sodiothermic reduction of TiCl4. Thus, the formation of titanium powder in the Hunter process may be attributed to the short-range electronically mediated reaction (SR-EMR).