Carboaluminothermic Production of Ferrotitanium from Ilmenite Through Thermal Plasma
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RESEARCH ARTICLE
Carboaluminothermic Production of Ferrotitanium from Ilmenite Through Thermal Plasma S. K. Samal1 · B. Mishra2 · S. C. Mishra1 Received: 20 June 2020 / Accepted: 28 August 2020 © The Minerals, Metals & Materials Society 2020
Abstract Ilmenite is the prime mineral used for the production of titania-rich slag and ferrotitanium alloy throughout the globe. In the current research, a 30 kW DC extended arc plasma reactor is employed for the aluminothermic reduction of ilmenite into ferrotitanium. For low-temperature operation, flux is added targeting low melting slag where CaO/Al2O3 ratio is varied from 0.8 to 1.6. Further, to lower down the Al consumption, carboaluminothermic reduction tests are carried out in stages without interruption. The effect of stage-wise reductant addition and CaO/Al2O3 ratio on ferrotitanium yield and titanium recovery is studied, corroborated to the slag chemistry. FeTi26 alloy is obtained through the carboaluminothermic smelting route with 25% excess stoichiometric Al in charge composition. The formation of calcium titanate and calcium aluminates governs slag chemistry and reduction kinetics. Graphical Abstract
Keywords Ilmenite · Thermal plasma · CaO/Al2O3 ratio · Ti recovery The contributing editor for this article was Mansoor Barati. * S. K. Samal [email protected] 1
Department of Metallurgical Engineering, NIT Rourkela, Rourkela 769008, Odisha, India
Suraj Products Ltd., Rourkela, Odisha, India
2
Introduction Extraction of titanium alloys from titanium oxide minerals involves carbothermic, aluminothermic, and silicothermic smelting routes. The carbothermic smelting of ilmenite produces pig iron and TiO2-rich slag, where the operating
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temperature is about 1650 °C to 1700 °C. Smelting of prereduced ilmenite (≈ 60% metallization of Fe) has several advantages over raw ilmenite, viz. 30% to 40% lower energy consumption, decreased amount of reaction gas, the lowered carbon content in pig iron, and reduced FeO content in final slag. The lowering of the FeO amount in the slag enriches TiO2 content (> 90%) of the final slag. The electrode consumption increases for longer process duration and also for the smelting of charge feed, where the exact stoichiometric amount of carbon is provided in charge feed [1–7]. The basics of ilmenite smelting, reaction kinetics, and phase evolution are studied and correlated by researchers [8–12]. In the smelting process, ilmenite ( FeTiO3) reduces into TiO2, Ti2O3, and Fe; the metallization of Fe from FeO is faster than the reduction of TiO2 to Ti2O3. The relationship between FeO and Ti2O3 is such that the composition of the slag follows M 3O5 stoichiometry. The amount of T i 2O 3 increases with increased equivalent TiO2 due to the lowering of FeO content in the slag. Another approach of producing TiC/Fe-TiC composites through plasma processing of ilmenite or titania-rich slag by adding excess stoichiometric carbon in charge is feasible where recovery rates are comparable higher [13–15].
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