Experimental investigation of phase equilibria and thermodynamic modeling of the CaO-SiO2-Al2O3-CaS oxysulfide system

摘要

Phase equilibria of the CaO-Al2O3-CaS, CaO-SiO2-CaS, and CaO-SiO2-Al2O3-CaS systems under low oxygen partial pressure have been experimentally investigated using equilibration and quenching techniques. Equilibrium phases were analyzed by Electron Probe X-ray Microanalysis (EPMA), and X-ray diffraction (XRD) analysis. Liquidus lines of all solid phases were successfully constructed in the temperature range investigated in the present study. In order to supplement the understanding of the phase equilibria, a thermodynamic modeling for this liquid oxysulfide were conducted using the Modified Quasichemical Model in the Quadruplet Approximation (MQMQA) assisted by the experimental data obtained in the present study as well as those available in literatures. A thermodynamic database for the CaO-SiO2-Al2O3-CaS system was developed in order to allow calculations of phase diagrams of various sections. This work is an extension of the previous thermodynamic modeling of sulfide capacity in the CaO-SiO2-Al2O3 slag system, thereby forming a consistent set of database. Liquidus projections of those oxysulfide systems are proposed for the first time using the thermodynamic model and the database.