THERMODYNAMIC MODELING OF SELENIDE MATTE CONVERTING

A by-product of the electrorefining of anode copper is a slime that co ntains significant amounts of silver, as well as selenium, copper, and other minor elements such as gold. Slimes are usually smelted to reco ver silver and gold. The thermodynamics of the smelting of such seleni um-rich materials have received scant attention, and the little that h as been done leads to erroneous predictions. In this work, a chemical potential diagram is developed that successfully explains previously p ublished observations. The smelting of slimes was also modeled with a computational thermodynamics package. Despite the simplicity of the mo del, which assumed that the activity coefficients of all species remai ned constant throughout oxidation, it gave good agreement with experim ental results published elsewhere for the compositions of all phases d uring smelting. The model was used to demonstrate that using air rathe r than pure oxygen significantly affected only the selenium content of the slag, reducing it to low levels. Smelting temperature in the rang e tested was shown not to be an important process variable.