RAS Institute of Metallurgy and Material Science named after A. A. Baikov (Moscow, Russia)

Anisonyan K. G., Candidate of Technical Sciences, Senior Researcher, kanisonyan@imet.ac.ru
Sadykhov G. B., Doctor of Technical Sciences, Chief Researcher, Head of Laboratory
Olyunina T. V., Senior Researcher
Kop’ev D. Y., Researcher
Mochenova N. N., Candidate of Geological-Mineralogical Sciences, Junior Researcher
Andreeva N. A., Researcher

The conditions for reductive nitriding roasting of perovskite concentrate from the Afrikanda deposit have been investigated, under which a nitride product suitable for low-temperature chlorination with titanium recovery in the form of titanium tetrachloride can be obtained. It has been demonstrated that the amount of SiO₂ additive introduced into the charge at 1325 °C directly influences both the degree of perovskite decomposition and the phase composition of the roasting products. The optimal SiO₂ addition is calculated based on a molar CaO/SiO₂ ratio of 2:1 in the charge, using the CaO content of the concentrate as the basis. Under these conditions, the degree of perovskite decomposition with concurrent conversion of titanium into its nitride reaches 85–90%. However, the presence of calcium silicates in the roasted product may reduce the efficiency of subsequent low-temperature chlorination of the nitride product due to increased chlorine consumption associated with CaCl₂ formation. It has been shown that calcium oxide can be removed by treating the nitride product with diluted hydrochloric acid solutions. This treatment simultaneously enables the extraction of rare earth metals (REM) into the leach solution. The extent of REM recovery depends on both the degree of perovskite decomposition and the leaching temperature. Subsequent precipitation of REM from the acidic leach solution allows their concentration into a bulk rare earth concentrate. Following chlorination of the nitride product, the solid residue consists of amorphous SiO₂ and residual undecomposed perovskite. This residue can be recycled to the head of the process as an additive to the fresh perovskite concentrate during nitriding roasting. Such recycling not only enhances the overall degree of perovskite decomposition but also significantly reduces the required consumption of SiO₂ additive in the charge.
The work is carried out within the framework of the state assignment No. 075-00320-26-00.

1. The state report “On the state and use of the mineral resources of the Russian Federation in 2023”. Moscow: [w. a p.], 2024. 710 p.
2. Reznichenko A. V., Shabalin L. I. Titanium deposits, metallurgy, chemical technology. Moscow: Nauka, 1986. 294 p.
3. Sadykhov G. B., Anisonyan K. G., Zablotskaya Yu. V., Goncharov K. V., Kop’ev D. Yu., Olyunina T. V., Tuzhilin A. S., Balmaev B. G. Features of titanium raw materials in Russia and prospects for its use for the production of titanium and its pigment dioxide. Metals. 2024. No. 3. pp. 3–20.
4. Reznichenko V. A. Ustinov V. S., Karyazin I. A., Khalimov F. B. Electrometallurgy and chemistry of titanium. Moscow: Izdatelstvo “Nauka”, 1982. 277 p.
5. Nikolaev А. I., Gerasimova L. G., Petrov V. B., Mayorov V. G. Perovskite concentrate – as a source for titanium and rare-metal products. Complex Use of Mineral Resources. 2015. Iss. 2. pp. 26–34.
6. Nikolaev A. I. Prospects of using the African deposit of perovskite ores as a raw material base for providing the domestic industry with strategic materials containing titanium and rare metals. Sever promyslennyy. 2007. Iss. 8. pp. 62–64.
7. Nikolaev A. I., Kalinnikov V. T. By-product manufacturing of rareearth metals during the processing of perovskite concentrate of the Afrikanda deposit. Tsvetnye Metally. 2013. Iss. 3. pp. 58–63.
8. Mayorov V. G., Nikolaev A. I., Kopkov V. K. Study of conditions for the separation of thorium from rare earth and other elements by precipitation from solutions with a high content of calcium chloride during the processing of perovskite. Tsvetnye Metally. 2007. Iss. 1. pp. 69–71.
9. Liu Y., Wang Y., Zhang Y., You Zh., Lv X. Mechanism on reduction and nitridation of micrometer-sized titania with ammonia gas. Journal of the American Ceramic Society. 2020. Vol. 103, Iss. 6. pp. 3905–3916.
10. Liu Y., He F., Hu Q., Huang Q., You Zh., Qiu G., Lv X. Isothermal reduction and nitridation kinetics of ilmenite concentrate in ammonia gas. Minerals Engineering. 2023. Vol. 203. 108319.
11. Swanepoel J. J. Process development for the removal iron from nitride ilmenite. University of Pretoria, 2010. 151 p.
12. Yaraghi A., Sapri M. H. A., Baharun N., et al. Aeration leaching of iron from nitrided malaysian ilmenite reduced by polystyrene-coal reductant. Procedia Chemistry. 2016. Vol. 19. pp. 715–720.
13. Adipuri A., Li Y., Zhang G., Ostrovski O. Chlorination of reduced ilmenite concentrates and synthetic rutile. Internation Journal of Mineral Processing. 2011. Vol. 100, Iss. 3-4. pp. 166–171.
14. Anisonyan K. G., Kop’ev D. Yu., Olyunina T. V., Sadykhov G. B. Research of the processes of reductive-nitrating roasting of perovskite concentrate with the addition of SiO. Matally. 2025. Iss. 4. pp. 5–14.
15. Mikhaylichenko A. I., Mikhlin E. B., Patrikeev Yu. B. Rare earth metals. Moscow: Izdatelstvo “Metallurgiya”, 1987. 231 p.