Thermodynamics of Titanium Oxide in Ladle Slags

Abstract

It is necessary to have information on the thermodynamic behavior of titanium oxide in ladle type slags in order to control the titanium content in several grades of steel. In the present study, the thermodynamics was determined from the equilibrium between Fe–C_sat–Ti and CaO–SiO₂-–30%Al₂O₃–MgO–TiOx slags in equilibrium with CO and from the equilibrium between Fe–C_sat–(1618)%Cr–Si–Ti and CaO–SiO₂–20%Al₂O₃–MgO–TiOx slags in equilibrium with CO. From the experiment with Fe–C_sat–Ti alloy, the activity coefficients of TiO_1.5 and TiO₂ vary with basicity from 0.3 to 1.5 and from 0.5 to 2.3, respectively. And from the experiment with Fe–C_sat–(1618)%Cr–Si–Ti alloy, the activity coefficients of TiO_1.5 and TiO₂ vary with basicity from 0.4 to 1.4 and from 0.6 to 3.5, respectively. The results obtained from the equilibrium between Fe–C_sat–(1618)%Cr–Si–Ti and CaO-SiO₂–20%Al₂O₃–MgO–TiOx slags were used to estimate the titaniumcontent of silicon-added stainless steel. Experiments were also conducted using Fe–Al–Ti melts in equilibrium with CaO–SiO₂–Al₂O₃–TiO_x slags saturated with MgO. In this case most of the titanium in the slag is present as TiO₂(Ti⁴⁺). The present results were used to predict the titanium content of aluminum-killed steel in equilibrium with ladle slags containing titanium oxide and the predictions agreed with plant data.