The sulfide capacities of CaO-SiO₂ melts containing MgO, FeO, TiO₂, and Al₂O₃

Abstract

The sulfide capacities of CaO-SiO₂ melts containing MgO, FeO, TiO₂, and A1₂O₃ have been measured by simultaneous equilibration within quartz capsules at 1776 K (1503 °C). The compositions of the melt samples and static gas phase within each capsule adjusted to establish a mutual equilibrium. The sulfide capacities, C_s, of all equilibrated samples must satisfy the following equation:

$$C_{{\text{S(}}j{\text{)}}} = \frac{{{\text{pctS}}_j }}{{pctS_i }} \bullet C_{S(i)} $$

The inclusion of several reference slags for which values of C_s are known from previous measurements enabled the calculation of the sulfide capacities of unknown samples. The influences of basic oxide substitutions (FeO and MgO) for CaO and acidic oxide substitutions (TiO₂ and A1₂O₃) for SiO₂ on the sulfide capacities of CaO-SiO₂ melts have been measured. When a basic oxide/acidic oxide ratio of 1.21 is maintained, MgO additions decrease sulfide capacity, while FeO, TiO₂ and A1₂O₃ additions increase sulfide capacity. The results are compared with earlier measurements on the influences of CaF₂ and B₂O₃, and the relative effects are discussed in terms of the activity of free oxide ions.