Lanthanothermic Reduction of TiO2

Abstract

The development of a new titanium (Ti) smelting process is highly desired to decrease the cost of Ti metal. In this study, a new method to produce a low-oxygen-concentration Ti directly from TiO2 using La as the reductant was developed. First, deoxidation experiments of metallic Ti using La as the deoxidant were conducted, and the ability of La to deoxidize metallic Ti was demonstrated. The oxygen concentrations in Ti were approximately 3900 ± 400 mass ppm O and 120 ± 50 mass ppm O at La/La2O3 and La/LaOCl/LaCl3 equilibria, respectively, at 1200 K (927 °C). Then, TiO2 reduction experiments utilizing La as the reductant were conducted to produce low-oxygen-concentration Ti directly. TiO2 pellets and Ti pieces were held in LaCl3 molten salt with a sufficient amount of La at 1200 K (927 °C) for 86 ks. After the reaction, the TiO2 pellets were reduced to metallic Ti without reaction inhibition by the formation of intermediate products. The oxygen concentration of the Ti pieces, which were placed in the molten salt with the TiO2 pellets, was 100 ± 50 mass ppm O. These results indicate that low-oxygen-concentration Ti containing less than 200 mass ppm O could be produced directly from TiO2 by utilizing La as the reductant in LaCl3 molten salt at 1200 K (927 °C). This new method is expected to lead to the development of a new industrial process for the production of ultra-low-oxygen-content Ti from Ti ore without a chlorination process.