Browsing by Author "Ruban, Artem V."

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Investigation of Phase Equilibria in the MnO–Al2O3 System by Differential Scanning Calorimetry Method
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Proidak, Yurii S.; Gladkykh, Volodymyr A.; Ruban, Artem V.; Riabtsev, O. O.
ENG: All slag from the production of manganese ferroalloys can be conditionally attributed to the system MnO–CaO–SiO2–Al2O3, since the sum of these oxides reaches 95–98% with MnO content from 18% to 48%. On the practical side, it is crucial to know the peculiarities of the behavior of silicate systems over a wide temperature range and in the presence of various additives. Differential scanning calorimetry was employed to study concentration–temperature transformations in melts corresponding to manganese aluminate, the low-temperature eutectic E1, and a manganese-rich region with 10% Al2O3 content. The conducted research indicates a congruently melting nature of manganese spinel MnAl2O4. The preservation of short-range order during the melting of MnAl2O4 affects the thermodynamic stability parameters of the compound and the temperature at the onset of manganese recovery during carbothermic reduction. The congruent melting of manganese spinel implies the presence of a second eutectic E2, positioned between MnAl2O4 and Al2O3. According to experimental data, the melting temperature of eutectic E2 is lower, approximately 1720 Celsius degrees.
Studying the Phase Equilibria in MnO-SiO2 System by the Differential Scanning Calorimetry (DSC) Method
(National Academy of Sciences of Ukraine, Publishing House Akademperiodyka, 2022) Proidak, Yurii S.; Gladkykh, V. A.; Ruban, Artem V.
ENG: Introduction. The formation of rational composition of molten slag is critical for smelting of manganese ferroal-loys. From seventy to ninety per cent of manganese ferroalloy slags are presented by manganese and silicon oxides. Information about phase equilibrium in MnO—SiO2 system has an important value for the development of new and the improvement of operating processes of beneficiating and agglomerating manganese raw material, manufacturing manganese ferroalloys, and smelting high-manganese electrical steels. Problem Statement. The analysis of scholarly research data on the diagram of the equilibrium state of MnO—SiO2 system has shown a difference between the temperature of eutectic melting and that of peritectic melting and a fundamental difference in the nature of these two types of melting. The diagram does not show the polymorphic transformation of rhodonite. Purpose. The purpose of this research is to study the behavior of manganese orthosilicate and metasilicate and the eutectic between them for specifying the structure of the MnO—SiO2 system equilibrium state diagram. Materials and Methods. The DSC method has been used to determine the temperature of phase transformations, melting and crystallization, of the samples that correspond to rhodonite (MnSiO3), tephroite with rhodonite (Mn2SiO4 + MnSiO3), and the eutectic located between them in terms of composition. Results. The temperature of tephroite congruent melting, the solidus and the liquidus of rhodonite incongruent melting have been determined more accurately. For the first time, the temperature of rhodonite polymorphic trans-formation at the phase transition γ-MnSiO3↔β-MnSiO3 accompanied with a volume fluctuation of up to 2% has been experimentally established. This has made it poss ible to plot the horizontal line of polymorphic transformation on the MnO—SiO2 system diagram. Conclusions. The obtained data on the equilibrium state of MnO—SiO2 system have given a clear idea of the slag system structure, which allows us to optimize cooling during the manganese agglomerate production; to ratio-nally select the slag melting conditions for the ferrosilicon manganese production; to improve slag thickening after the release of smelting products; to justify slag crystallization behavior for the production of slag-cast products.