Thermodynamic Modeling of the Fuming of Copper Smelting Slag

To describe the processes of fuming copper smelting slags by the products of methane conversion by oxygen at oxygen consumption coefficients (alpha) varying from 0.25 to 0.75 in the temperature range 1473-1773 K, we have developed a thermodynamic modeling technique for open systems with fractional introduction of an initial reducing gas and periodic removal of a metallic phase and waste gases from a working medium. Relations between the contents of iron and zinc oxides in an oxide melt and the degrees of their reduction and the temperature and the amount of the introduced reducing agent are revealed. The thermodynamic equilibrium of a system is calculated on the assumption that solutions are ideal; that is, the activity coefficient of zinc oxide is 1. Under the real conditions of the slag melt of copper smelting, a(ZnO) is close to 3. Therefore, the quantitative indicators of industrial smelting differ from the calculated ones. However, the change in the smelting parameters relative to each other would be the same. The main result of this work is a comparative analysis of the processes depending on the reducing gas temperature and composition. The amount of conversion products and, accordingly, natural gas required for their production, which is necessary for metal reduction to a given degree of zinc recovery, significantly depends on the gas temperature and composition. The data obtained are useful for predicting the thermal extraction processes that occur during the extraction of useful components from nonferrous metallurgy slags.