PRODUCTION OF TITANIUM POWDER THROUGH AN ELECTRONICALLY MEDIATED REACTION

摘要

Production of titanium powder by an electronically mediated reaction (EMR) was explored with the purpose of developing an alternative to the Kroll process. Feed material, TiO2, and reductant calcium alloy containing nickel, and so on, were charged into electronically isolated locations in CaCl2 molten salt at 1173 K. The flow of current through an external path between the feed and reductant locations and the electrochemical potentials of the feed electrode were monitored during the reduction experiment. Although liquid Ca-Ni alloy was used as the reductant, pure titanium powder with low nickel content was obtained after the experiment. This clearly demonstrates that titanium powder can be produced by electrochemical reactions, without direct physical contact between the feed (TiO2) and reductant (calcium alloy). In some experiments, pure titanium in sponge form with 99.5 mass% purity (3500 mass ppm O) was obtained. This method has the potential to prevent the accumulation of impurities in the titanium deposits since impurities in the molten salt can be trapped by the reductant alloy placed in a different location from the titanium reduction site. When combined with conventional molten salt electrolysis (MSE) of CaCl2 for reductant production, the energy efficiency of the reduction process can also be improved. The MSE of CaCl2-CaO molten salt was investigated for producing calcium alloy reductant. The differences and features of various reduction processes are discussed.