Ural Federal University named after the first President of Russia B. N. Yeltsin, Ekaterinburg, Russia:

M. V. Belousov, Assistant Professor of Aluminium Metallurgy Chair, e-mail: MetAlMg@yandex.ru
D. F. Rakipov, Assistant Professor of Light Metals Metallurgy Chair (Metallurgical Faculty)

Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, Ekaterinburg, Russia:

E. N. Selivanov, Head of Institute

This paper gives the results of studies of magnesium recovery by ferrosilicon (75%) from the calcined dolomite of Ural deposits (Boitsovskoe and Chernorechenskoe). Analysis of chemical composition of dolomite samples showed that their quality is rather high (there are almost no impurities of alkali and heavy metals), but they differ by high content of calcium carbonate, which determines the peculiarity of their use in magnesium production. It is established that the structure of dolomite samples is characterized by a grain size of calcium carbonate inclusions. The sample I is characterized by CaCO₃ inclusions with the particle size of 10–20 μm (7%), and the sample II is larger — CaCO₃ inclusions with the particle size of 20–30 μm (12.5%). The paper presents the results of thermodynamic modeling of multi-component system MgO – CaO – Si – Fe – Mg – Сa₂SiO₄ – Сa₃SiO₅, according to which the excess of calcium oxide in the mixture (CaO/Si = 2.2–2.5) makes possible to recover magnesium from its oxide with ferrosilicon with formation of Са₃SiO₅ compound. This paper discusses the features and parameters of magnesium recovery process, which laboratory simulations were carried out using high-temperature setting consisting of electric furnace, high-alloy chromium-nickel steel retort, vacuum pump and vacuum gauge. During the experiments, the pressure and the temperature in the retort were maintained at 0.1 kPa and 1195 °C, while the temperature in the condenser was maintained at 475–500 °C. The mixture of calcined dolomite with ferrosilicon (FS 75 (ФС 75)) was extruded at a pressure of 1000 kg/cm2 into cylindrical pellets (diameter, equal to 20, height, equal to 20–22 mm) weighing 12–13.5 g. During the experiment, there were identified the optimal parameters for magnesium recovery, which reached the output of metallic magnesium, equal to 81.2%. It is established that the increase of content of calcium oxide in the charge to CaO:MgO:Si = 2.5:2:1 leads to the reduction of magnesium output by 3% and increase the flow of charge by 9.5%. Allocated in the course of dolomite processing, magnesium condensate has a high quality (content of magnesium is 99.5%), so it can be recommended to use for alloy production without further refining. The formed retort residues containing 57–60% CaО, 20–24% SiO2, 6.0–6.5% MgO, 3.8–4.0% Fe, 1.3–1.7% Al₂O₃, have similar composition with the Portland cement and, after the separation of metal component, they can be used as an additive in its production.

1. Zuliani D. J. Developments in the Zuliani Process for Gossan Resources Magnesium Project. The collection of works 69^th Annual World Magnesium Conference IMA. San Francisco, California USA, 2012. pp. 113–123.
2. Abdellatif M. A., Freeman M. J. Mintek Thermal Magnesium Process: Status and Prospective. Advanced Metal Initiative, Department of Science and Technology. Johannesburg, South Africa, 2008. pp. 1–14.
3. Hu W., Feng N., Wang Y., Wang Z. Magnesium Production by Vacuum Aluminothemic Reduction of A Mixture of Calcined Dolomite and Calcined Magnesite. Magnesium Technology 2011 : TMS Annual Meeting. 2011. pp 43–47.
4. Hu W., Liu J., Feng N. Analysis of New Vacuum Reduction Process in Magnesium Production. Non-ferrous Mining and Metallurgy. 2010. No. 4. pp. 40–42.
5. Prentice L. H., Nagle M. W., Barton T. R., Tassios S., Kuan B. T. Carbothermal Production of Magnesium: CSIRO's MagSonic™ Process. Magnesium Technology 2012 : TMS Annual Meeting. 2012. pp. 31–35.
6. Godovoy otchet Otkrytogo Aktsionernogo Obshchestva “Solikamskiy magnievyy zavod” za 2014 god (Annual report of JSC “Solikamsk Magnesium Works” for 2014). Available at: http://смз.рф/raport/2015/2014_annual_report_SMW.pdf (in Russian).
7. Belousov M. V., Butorina I. V., Rakipov D. F. Ekologicheskie aspekty proizvodstva magniya (Environmental aspects of magnesium manufacturing). Tsvetnye Metally = Non-ferrous metals. 2013. No. 7. pp. 64–68.
8. Belousov M. V., Rakipov D. F., Nikonenko E. A., Kolesnikova M. P. Issledovanie mekhanizma razlozheniya dolomita Srednego Urala (The research of dolomite decomposition on the Middle Urals). Tsvetnye Metally = Nonferrous metals. 2012. No. 4. pp. 50–52.
9. Moiseev K. G. Termodinamicheskoe modelirovanie v neorganicheskikh sistemakh (Thermodynamic modeling in inorganic systems). Chelyabinsk : South Ural State University, 1999. 256 p.
10. Strelets Kh. L., Tayts A. Yu., Gulyanitskiy B. S. Metallurgiya magniya (Magnesium metallurgy). Moscow : Metallurgizdat, 1960. 480 p.
11. Ryabukhin A. I., Savelev V. G. Fizicheskaya khimiya silikatov i drugikh tugoplavkikh soedineniy (Physical chemistry of silicates and other refractory compounds). Moscow : D. Mendeleev University of Chemical Technology of Russia, 2003. 96 p.
12. Pidgeon L. M., Alexander W. A. Thermal production of magnesiums pilot plant studies on the retort ferrosilicon process. New York Meeting: reduction and refining of non-ferrous metals: Transactions of the American Institute of Mining and Materials Engineering. 1944. pp. 315–352.
13. Minic D., Manasijevic D., Dokic J. Silicothermic reduction process in magnesium production. Journal of Thermal Analysis and Calorimetry. 2008. No. 2. pp. 411–415.
14. Wulandari W., Rhamdhani M. A., Brooks G. A., Monaghan B. J. Proce Distribution of Impurities in Magnesium Production via Silicothermic Reduction edings of European Metallurgical Conference. Innsbruck, Austria. 2009. pp. 1401–1417.