Relationship between the Aluminum and Oxygen and Sulfur Partitions for Molten Iron and a CaO-Al2O3-ZrO2 Slag in Equilibrium

Abstract

The relationship between the aluminum–oxygen and sulfur distribution ratio for molten iron and a CaO–Al2O3–ZrO2 slag in equilibrium at 1 873 K was studied using an Al2O3 or CaO-stabilized ZrO2 crucible. The slag and molten iron equilibrated with CaO·2Al2O3 and Css (cubic solid solution in CaO–ZrO2 system) in the Al2O3 crucible, and with Ca·OZrO2 and Css in the ZrO2 crucible. These equilibrium states coincided with the phase diagram of CaO–Al2O3–ZrO2. From the concentrations of aluminum and oxygen dissolved in molten iron, the Al2O3 activity in the slag was determined to be 0.393 in the Al2O3 crucible and 0.385 in the ZrO2 crucible. These activities were compared with the data in the CaO–Al2O3 and CaO–ZrO2 systems. The sulfur distribution ratio was higher a little in the ZrO2 crucible than in the Al2O3 crucible and increased with aluminum content. The sulfide capacity of the fluxes was determined to be 8.77×10−5 and 9.10×10−5 in the Al2O3 and ZrO2 crucibles, respectively.