Chemical modeling of high temperature aqueous processes

Chemical modeling is a very powerful tool to predict and understand the behavior of complex aqueous processing systems. Equally powerful is the educational aspect associated with building such models. In recent years, chemical modeling has undergone tremendous development. The new capabilities of various software have changed the way engineers simulate aqueous solutions in hydrometallurgical processes. This paper presents new developments and strategies to model the chemistry of high temperature aqueous processing systems. The acid pressure leach of nickeliferous laterites is used as an example. In this work, calculation of standard thermodynamic properties of aqueous species was performed with the revised Helgeson-Kirkham-Flowers (HKF) model as well as with the Density model. Nonidealities, including weak ion-pair formations, were treated through the Bromley-Zemaitis ion interaction method. The above models were implemented through the OLI-Systems® commercial software. Monometallic sulphate solutions like Al2(SO4)3-H2SO4, MgSO4-H2SO4, NiSO4-H2SO4, Fe2O3-H2SO4 were used to fit new thermodynamic parameters which were verified on progressively more complex solution mixtures. Finally, simulation results of laterite leach solutions were compared with available experimental data and very good agreement was found.