Baykov Institute of Metallurgy and Materials of the Russian Academy of Sciences, Moscow, Russia:

D. Yu. Kopiev, Researcher, e-mail: Kopievd@yandex.ru
K. G. Anisonyan, Senior Researcher
T. V. Olyunina, Senior Researcher
G. B. Sadykhov, Head of Laboratory

While Russia possesses its own major deposits of titanium, all the sites that produce titanium dioxide pigment in Russia absolutely rely on imported materials. This is due to the fact that, in terms of the mineral and chemical compositions, the Russian titanium ores differ from the standard titanium ore used in the TiO₂ pigment production. Leucoxene ores of the Yarega deposit could potentially be used for TiO₂ pigment production. However, they would first need to go through metallurgical processing aimed at enhancing titanium oxide reactivity. This paper describes the results of a study that looked at preparing the Yarega deposit leucoxene ores for a sulfuric acid process. This was realized with the help of reducing roasting aimed at transforming TiO₂ into Ti₃O₅ (anosovite). A thermodynamic analysis was carried out for the carbon reduction of the concentrate in the temperature range of 1050–1500 ^оС. The authors looked at how the reduction conditions could influence the phase composition of the products and their recoverability in sulfuric acid. It was found that, in the range of 1350–1400 ^оС and with the addition of 5–7.5% of solid reducing agent (soot), the sulfuric acid recovery of TiO₂ could be above 90%. If the temperature is raised to 1450 ^оС, a high sulfuric acid recovery can be achieved when adding 2.5–3.0% of the reducing agent. It indicates that titanium dioxide can be almost completely reduced to anosovite. Having analysed the thermodynamic and experimental data, the authors defined how rutile is reduced in the leucoxene grains. It is shown that the final products also contain over- and under-reduced phases of titanium, which is caused by the diffusion processes characteristic of the leucoxene grain recovery. The study demonstrated a high sulfuric acid recoverability of the leucoxene concentrate reduced under optimum conditions and the applicability of leucoxene concentrate as a primary material in the production of TiO₂ pigment using sulfuric acid process.
This research was carried out under the Governmental Assignment No. 007-00129-18-00.

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