Effect of oxygen partial pressure on the viscosity of iron-bearing alkaline-earth silicate slags

Sukenaga, Sohei*; Osugi, Takeshi  ; Inatomi, Yosuke*; Saito, Noritaka*; Nakashima, Kunihiko*

Viscosity changes of RO-SiO-FexO (R = Ca, Sr, Ba) melts due to changes in the oxidation states of the iron ions by systematically varying the oxygen partial pressure were measured at 1773 K. The initial compositions of the samples were 30RO-60SiO-10FeO(mol%), and the ratio of Fe toFe in the RO-SiO-FexO melts increased with increasing oxygen partial pressure in all samples. Meanwhile, the viscosity of all the RO-SiO-FexO melts decreased with increasing Fe to total-Fe ratio (Fe/t-Fe). The data indicate that the increase in the amount of Fe ions, which behave as network modifiers, would result in depolymerization of the silicate anions. In addition, the viscosity of the melts increased in the order of alkaline-earth cationic radius (Ba Sr Ca) when the Fe/t-Fe values of the melts were comparable. This would be due to the change in the coordination structure of Fe in the melts.