Vapor pressure of zinc and zinc chloride in the Fe_tO-CaO- SiO₂-Al₂O₃ slag system

Vapor pressure of zinc from the Fe_tO-CaO-SiO₂-Al ₂O₃ slag system was measured by the Knudsen effusion method under conditions with varying parameters such as temperature, slag compositions, and initial contents of zinc and chlorine. In the thermodynamic estimations using thermodynamic parameters under the experimental temperature range, for slag samples without Cl addition, it suggests that metallic Zn is the only vapor species. In the case of Cl addition, gaseous ZnCl₂ is predominant and the formation ratio of metallic Zn and FeCl₂ can be neglected. In the measurements, the vapor pressures of metallic Zn and ZnCl ₂ increase with increasing temperature. For ZnCl₂, the logarithm of vapor pressure (In P) is a linear function of the reciprocal of temperature (1/T), while in the case of gaseous metallic Zn, a non-linear relationship is observed between In P and 1 /T, The slag basicity exhibits the different effects on the vapor pressures of metallic Zn and ZnCl₂. The former increases with increasing the slag basicity, while the latter decreases. A high FeO content in the slag tends to increase the vapor pressure of metallic Zn and ZnCl₂.