Antonio Romero-Serrano

Calculation of sulfide capacities of multicomponent slags

The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A12O3 and TiO2 as components. The model has been extended to calculatea priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO2-Al2O3-TiO2-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria.

Extensions of a structural model for binary silicate systems

Our earlier structural model for binary silicate melts and glasses is extended. More general expressions for the enthalpy and nonconfigurational entropy are given. Expressions for partial thermodynamic properties are derived. A least-squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously within experimental error limits. The model is extended from MO-SiO2 to M2O-SiO2 solutions. Data in acidic melts is well represented for the Na2O-SiO2 system. Examples of optimizations for the MnO-SiO2, CaO-SiO2, and Na2O-SiO2 systems are presented. The model is extended to include sulfide ion. Good predictions of sulfide capacities are obtained.

Thermodynamic modeling of the BaO-SiO2 and SrO-SiO2 binary melts

The evaluation of the thermodynamic properties and the phase diagrams for the binary BaO-SiO2 and SrO-SiO2 systems is carried out using a structural model for silicate melts and glasses. This thermodynamic model is based on the assumption that an addition of metal oxides to silica results in the depolymerization of the silicon-oxygen network, with a characteristic free energy change. A least squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously. In this manner, data for the above binary systems have been analysed and represented with a small number of parameters. The resulting equations represent the thermodynamic and phase diagram data for the alkaline-earth oxide-silica systems within error limits for most of the experimental data. In particular, the measured limiting liquidus slope, at XSiO2 = 1, is well reproduced.