|Cite this article as:|
|Jinfa Liao and Baojun Zhao, Phase equilibria studies of the titanomagnetite and ilmenite smelting slags, Int. J. Miner. Metall. Mater.,(2021). https://doi.org/10.1007/s12613-021-2376-1|
Phase equilibrium information of the slag plays an important role in pyrometallurgical processes to obtain optimum fluxing conditions and operating temperatures. Smelting reduction of titanomagnetite and ilmenite ores in iron blast furnace can form Ti(CN) particles causing increased viscosities of slag and hot-metal. HIsmelt has been developed in recent years for ironmaking which does not need coke and sinter. Formation of Ti(CN) in the HIsmelt process is avoided because the oxygen partial pressure in the process is higher than that in the blast furnace. Smelting of TiO2-containing ores in HIsmelt process results in Al2O3–MgO–SiO2–CaO–TiO2 slag. Phase equilibria in this slag system have been investigated using equilibration, quenching and electron probe microanalysis (EPMA) technique. The experimental results are presented in two pseudo-binary sections, which represent the process of HIsmelt to treat 100% titanomagnetite ore and 100% titanomagnetite + 50% ilmenite respectively. The primary phases observed in the composition range investigated include pseudo-brookite M3O5 (MgO·2TiO2–Al2O3·TiO2), spinel (MgO·Al2O3), perovskite CaTiO3 and rutile TiO2. The results show that the liquidus temperatures decrease in the TiO2 and M3O5 primary phase fields with increasing CaO concentration and increase in the spinel and CaTiO3 primary phase fields with increasing CaO concentration. Calculation of solid-phase fractions from the experimental data has been demonstrated. Effect of the basicity on liquidus temperatures of the slag has been discussed. It seems that smelting of titanomagnetite plus ilmenite ores has significant advantages to obtain low-sulphur hot-metal and high-TiO2 slag. Experimentally determined liquidus temperatures are compared with the FactSage predictions to evaluate the existing thermodynamic databases.