Thermodynamics of iron oxide in FexO-dilute CaO+Al2O3+FexO fluxes at 1873 K

The distribution of iron between FexO-dilute CaO + Al2O3 + FexO fluxes and Pt + Fe alloys, as well as the redox equilibrium of iron ions in these fluxes, was experimentally investigated in pressure-controlled CO2/CO gas at 1873 K. Total iron content in flux (pet Fe-T) and the ratio of (pct Fe2+) to (pct Fe-T) in fluxes with constant X-CaO/X-Al2O3 can be related to the activity of iron, a(Fe), and the partial pressure of oxygen, p(O2), using the following equation: (pct Fe-T) = {(CFe2+) p(O2)(1/2) + (CFe3+) pO(2)(3/4))} a(Fe) (pct Fe2+)/(pct Fe-T) = 1/1 + {(CFe3+)/(CFe2+)} X p(O2)(1/4) where CFe2+ and CFe3+ are the ferrous and ferric ion capacities, respectively, defined as CFe2+ = (pct Fe2+/a(Fe)) p(O2)(-1/2), CFe3+ = (pct Fe3+)/a(Fe) p(O2)(-3/4) The present article applies these parameters to the evaluation of the activity coefficient of FexO at infinite dilution, gamma(FexO)degrees, relative to the liquid iron oxide in equilibrium with iron. Furthermore, the composition dependence of gamma(FexO)degrees is discussed.