Investigation of phase formation during roasting of chromium pellets by the thermodynamic simulation method

Abstract

One of the ways to optimize the quality of production of chromium raw materials is to introduce slags capable of forming a slow-melting silicate compound to improve technical and economic indicators. The reason for the choice of these components is that they are used to regulate the slag mode in the process of melting ferrochrome alloy. The article presents the results of thermodynamic changes in the use of free chromium slag in the high-temperature zone and easily melting aluminosilicate slags of various compositions. Thermodynamic modeling during the firing of chrome pellets was carried out using the “TERRA” software package. Full thermodynamic modeling was carried out on the basis of a multicomponent CaO-MgO-Fe₂O₃-Al₂O₃-SiO₂ system at a temperature range of 800-1800°C and at a pressure of 0.1 MPа. As initial data for determining the parameters of thermodynamic equilibrium for the actual compositions of the chromium pellet firing charges, the host rock of chromium ore (the host part of the rock) and fluxing additives (aluminosilicate material) with different ratios were used. It was found that with the following optimal content of the fluxing material: SiO₂ 50-55%; Al₂O₃ 14-16%; CaO 12-14%; MgO 5-8%; FeO 5-8%, the sintering process of chrome pellets can be carried out at relatively low temperatures (1200-1300°C). As a result, phase compositions with low melting points (CaAl₂Si₂O₈, CaMg (Si₂O₆), MgSiO₃) were determined, where they can affect the technical and economic performance of the production of chrome pellets