Effect of Sulfur on Liquidus Temperatures in the ZnO-“FeO”-Al₂O₃-CaO-SiO₂-S System in Equilibrium with Metallic Iron

The phase equilibria in the ZnO-“FeO”-Al₂O₃-CaO-SiO₂-S system have been determined experimentally in equilibrium with metallic iron. A pseudoternary section of the form ZnO-“FeO”-(Al₂O₃+CaO+SiO₂) for CaO/SiO₂ = 0.71 (weight), (CaO+SiO₂)/Al₂O₃ = 5.0 (weight), and fixed 2.0 wt pct S concentration has been constructed. It was found that the addition of 2.0 wt pct S to the liquid extends the spinel primary phase field significantly and decreases the size of the wustite primary phase field. The liquidus temperature in the wustite primary phase field is decreased by approximately 80 K and the liquidus temperature in the spinel primary phase field is decreased by approximately 10 K with addition of 2.0 wt pct S in the composition range investigated. It was also found that iron-zinc sulfides are present in some samples in the spinel primary phase field, which are matte appearing at low zinc concentrations and sphalerite (Zn,Fe)S at higher zinc concentrations. The presence of sulfur in the slag has a minor effect on the partitioning of ZnO between the wustite and liquid phases but no effect on the partitioning of ZnO between the spinel and liquid phases.