Thermodynamic modeling of the phase diagrams of oxide systems FeO-MgO, FeO-Cr2O3, MgO-Cr2O3 and FeO-MgO-Cr2O3

Thermodynamic modeling of the liquidus lines coordinates of the phase diagrams of the FeO-MgO, FeO-Cr2O3, MgO-Cr2O3 systems and liquidus surface coordinates of the phase diagram of the FeO-MgO-Cr2O3 system was carried out. In the course of the work, the energy parameters of the theory of subregular ionic solutions used in the calculation were determined. According to the results of the simulation, the coordinates of the points of nonvariant transformations on the phase diagrams of the studied systems are determined. The obtained results on thermodynamic modeling of the liquidus lines coordinates of the phase diagrams of the systems FeO-MgO, FeO-Cr2O3, MgO-Cr2O3 were compared with scattered literature data for the systems under study. According to the calculation results, the enthalpies and entropies of formation of the compounds FeCr2O4 and MgCr2O4 from the components of the oxide melt of the FeO-Cr2O3 and MgO-Cr2O3 systems, respectively, were determined. According to the simulation results, the enthalpy of formation of ferrochromite from the components of the oxide melt is 157 376 J/mol, and the entropy is 44.71 J/(mol•K). The enthalpy and entropy of the formation of magnesiochromite from the components of the oxide melt turned out to be 389 100 J/mol and 123.19 J/(mol•K), respectively. For the first time, results were obtained for calculating the liquidus surface coordinates of the FeO-MgO-Cr2O3 system. The phase diagram of the FeO-MgO-Cr2O3 system is characterized by extensive equilibrium regions of the oxide melt with solid solutions of oxides and with solid solutions of spinels. The results obtained in the course of this work are of interest for analyzing of the interaction metal and slag with the furnace lining during steelmaking processes.