Arsenate capacities of copper smelting slags

The arsenate capacity model, based on the Reddy-Blander model, was developed for copper smelting slags. The arsenate capacities of FeO-SiO₂, CaO-SiO₂, MgO-SiO₂, FeO-FeO_1.5-CuO_0.5-MgO-SiO₂, and FeO-FeO_1.5-CuO_0.5-CaO-MgO-SiO₂ slags in equilibrium with different grades of copper mattes (21 to 79 wt pct Cu) at 1573 K were studied. The calculated arsenate capacities using the RB model in copper slags a priori is in very good agreement with the available experimental data. The results show that the calculated arsenate capacities for these slags are found to be directly related to two independent experimental quantities: the equilibrium constant K of the arsenate forming reaction 2/3;MO (1)+As (1)+5/4O₂ (g)=M_3/2AsO₄ (l, s), and the activity of the base metal oxides in the binary MO-SiO₂ slags. Furthermore, this arsenate capacity model can be used for a priori prediction of arsenic behavior in a wide range of slag and matte composition, temperature, and in copper smelting conditions. Such predictions are very useful in understanding the behavior of arsenic in the current and eventually future nonferrous metal processes. This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties & Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002.