Effect of Gas Atmosphere on the Phase Chemistry in the CaO–FeO–Fe₂O₃–SiO₂ System Related to Iron Ore Sinter-making

Abstract

Experimental phase equilibria studies have been carried out to investigate the phase chemistry in the CaO–“Fe₂O₃”–SiO₂ system related to the iron ore sinter making in 1 atm CO₂ at 1200–1230°C. The measurements have been performed using a modified experimental technique involving high temperature equilibration and rapid quenching followed by electron probe X-ray microanalysis (EPMA). In contrast to the equilibria in air, the experimental results show that no silico-ferrite of calcium (SFC solid solution) is formed in 1 atm CO₂ within the temperature range investigated; that is, the SFC phase is not stable at liquidus temperatures. The liquidus for the iron-rich corner of the CaO–“Fe₂O₃”–SiO₂ system in CO₂ atmosphere for the spinel (magnetite Fe₃O₄) and dicalcium silicate (C₂S = Ca₂SiO₄) primary phase fields has been proposed.