TECHNOLOGY OF PRODUCING Mn-Si-Ba-Fe ALLOY BY CARBOTHERMAL METHOD

The results of theoretical and experimental studies of the technology for producing a complex barium-containing ferroalloy based on manganese for out-of-furnace processing of metal products are presented. Ferroalloys containing barium are of the greatest interest due to the unique complex of its physical and physicochemical properties (solubility in liquid iron is 1.22·10 at.% at T=1600K; relative modifying capacity 69.86·10; T=983K; T=1910K; heat of interaction with iron is 212 kJ/mol; enthalpy of dissolution is 300 kJ/g-at at T=1700K). The diagrams of material ratios of the oxide BaO-SiO-MnO-FeO and metallic Ba-Si-Mn-Fe systems were constructed to determine the rational ratio of the components of the charge and the composition of the alloy by the method of thermodynamic-diagram analysis. This is a simple method for studying phase patterns of complex systems taking into account the features of state diagrams. The values of the change in Gibbs energy (ΔG) are determined in a homogeneous liquid-phase state using the Gibbs software package developed by scientists of the Chemical and Metallurgical Institute named after Zh. Abishev. The tie lines of coexisting phases are drawn according to Hess's rule. It was established that the rational composition of the batch for obtaining an alloy with a barium content of more than 1.5% is located in the quasi-system FeSiO-BaSiO-MnSiO-SiO, and the composition of the alloy is in the region of the tetrahedron FeSi-BaSi-MnSi-Si. The large-scale laboratory tests of the smelting of a complex barium-containing ferroalloy based on manganese in an ore-thermal furnace with a transformer capacity of 200 kV×A by a slag-free carbothermal method were carried out on the basis of the results of a thermodynamic-diagram analysis. Manganese ore from the Mynaral deposit (71.67% MnO), barite ore from the Zhumanai deposit (74.35% BaSO), and quartzite from the Tekturmas deposit (97.05% SiO) were used as initial raw materials. Chinese coke (82.70% C) was used as a reducing agent. It was established that the transition of barium into the alloy is determined by the accompanying process of silicon reduction. It was determined that to obtain an alloy with 1.5% Ba, the ratio Si/(Mn+Fe) should be at the level of 0.6; for an alloy with a content of 10% Ba - 1.1.