Estimation for Iron Redox Equilibria in Multicomponent Slags

The knowledge of redox equilibria of iron in multicomponent molten slags is of significant importance to understand the viscosity, electrical conductivity and structure of iron-containing slags. However, the available data of molar ratio of ferric ion to ferrous ion are limited due to the difficulty of experiment and heavy workload. In this study, a model was established to estimate the XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ (normally, most of ferric ions exist in the form of complex anions such as FeO2−$${\rm{FeO}}_2^ - $$) ratio in CaO–MgO–Al2O3–SiO2–“FeOt” slags, which can give good estimation results compared to the experimental measured values. From the model, by increasing oxygen partial pressure or decreasing temperature, the XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio will increase. Different components have different influences on XFeO2−/XFe2+$${{{X_{{\rm{FeO}}_2^ -}}} \mathord{\left/{\vphantom {{{X_{{\rm{FeO}}_2^ -}}} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}} \right. \kern-\nulldelimiterspace} {{X_{{\rm{F}}{{\rm{e}}^{2 +}}}}}}$$ ratio: CaO and MgO are beneficial for the increase of this ratio, but Al2O3 and SiO2 have reverse effects