Coupled experimental and thermodynamic modeling studies for metallurgical smelting and coal combustion slag systems

An extensive research program focused on the characterization of various me tallurgical complex smelting and coal combustion slags is being undertaken. The research combines both experimental and thermodynamic modeling studies . The approach is illustrated by work on the PbO-ZnO-Al2O3-FeO-Fe2O3-CaO-Si O2 system. Experimental measurements of the liquidus and solidus have been undertaken under oxidizing and reducing conditions using equilibration, que nching, and electron probe X-ray microanalysis. The experimental program ha s been planned so as to obtain data for thermodynamic model development as well as for pseudo-ternary Liquidus diagrams that can be used directly by p rocess operators. Thermodynamic modeling has been carried out using the com puter system FACT, which contains thermodynamic databases with over 5000 co mpounds and evaluated solution models. The FACT package is used for the cal culation of multiphase equilibria in multicomponent systems of industrial i nterest. A modified quasi-chemical solution model is used for the liquid sl ag phase. New optimizations have been carried out, which significantly impr ove the accuracy of the thermodynamic models for lead/zinc smelting and coa l combustion processes. Examples of experimentally determined and calculate d liquidus diagrams are presented. These examples provide information of di rect relevance to various metallurgical smelting and coal combustion proces ses.