Real-solution stability diagrams for copper-ammonia-chloride-water system

Abstract

A comprehensive thermodynamic model, which combined the Helgeson-Kirkham-Flowers (HKF) equation of state for standard-state thermodynamic properties of all species with realistic activity coefficient model developed by BROMLEY, was used to calculate the thermodynamic equilibrium, and a graphical method was developed to construct predominance existence diagrams (PED) for copper-ammonia-chloride in the presence of realistically modeled aqueous solutions. The existence of the different predominant chemical species for Cu(II) predicted by the diagrams was corroborated by spectrophotometrical studies and X-ray diffractometry. The simulated and experimental results indicate that the predominance of a given species in solution strongly depends on the pH value in this system. More quantitative information on real copper hydrometallurgy in the presence of ammonia and chloride can be obtained from these diagrams compared with the conventional predominance existence diagrams.