Thermodynamic Modeling of the Carbothermic Reduction of Manganese from the MnO–Fe2O3–CaO–SiO2–MgO–Al2O3 Oxide Melt

• Published in: Russian metallurgy Metally 2022-11, Vol.2022 (11), p.1434-1440
• Main Authors: Salina, V. A., Zhuchkov, V. I.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Calcium oxide; Calcium silicates; Carbon; Carbothermic reactions; Cementite; Chemical composition; Chemistry and Materials Science; Ferroalloys; Ferromanganese; Iron carbides; Liquid phases; Magnesium oxide; Manganese dioxide; Manganese ores; Manganese oxides; Mass ratios; Materials Science; Melt temperature; Metallic Materials; Metallurgy; Mixtures; Modelling; Reducing agents; Silicon carbide; Silicon dioxide; Slag; Software packages; Thermodynamics
• ISSN: 0036-0295; 1555-6255; 1531-8648
• DOI: 10.1134/S0036029522110118

The carbon reduction of manganese of in the multicomponent system MnO–Fe 2 O 3 –CaO–SiO 2 –MgO–Al 2 O 3 in a liquid-phase state is subjected to thermodynamic modeling. This system is an oxide mixture, which is close to the compositions of manganese ore, and a high-carbon ferromanganese slag at mass ratios of 100 : 0, 95 : 5, 88 : 12, and 75 : 25, respectively. The chemical compositions of the system components are as follows (%): (1) manganese ore contains 44.3 MnO, 1.1 MnO 2 , 11.2 Fe 2 O 3 , 28.4 CaO, 9.3 SiO 2 , 5.4 MgO, and 0.3 Al 2 O 3 ; (2) slag of high-carbon ferromanganese, 8.8 MnO, 0.3 FeO, 40.3 CaO, 32.4 SiO 2 , 5.8 MgO, and 12.4 Al 2 O 3 . The parameters of the initial state of the system are as follows: the temperature range is t = 1400–1700°C at a step of 100°C and the total pressure is 0.1 MPa. The consumption of carbon as a reducing agent has been increased by 5% relative to stoichiometric one for the reduction of iron and manganese and by 8% relative to the metal mass for the formation of iron, manganese, and silicon carbides. The modeling was carried out using the HSC Chemistry 6.12 software package (Outokumpu, Finland). The thermodynamic characteristics of the Mn 5 C 2 manganese carbide are introduced into the software database, and the thermodynamic constants of the compounds existing in the database (Fe 3 C, Fe 2 O 3 , FeO, MnO 2 , Mn, Mn 3 C, Mn 7 C 3 , Mn 23 C 6 , SiC) are corrected. An increase in the melt temperature from 1400 to 1700°C is found to cause an increase the degree of manganese reduction η Mn at various slag contents in the system. An increase in the amount of high-carbon ferromanganese slag in the mixture from 0 to 25% decreased η Mn from 89.9 to 88.6%. Manganese carbides (Mn 3 C, Mn 5 C 2 , Mn 7 C 3 ) are present in the metallic phase, and calcium silicate (CaSiO 3 ) is present in the oxide phase. The chemical compositions of the metal and slag melts are determined at a temperature of 1600°C. The simulation results can be applied to develop a technology for the production of manganese-containing ferroalloys using the production waste in metallurgical processing.