Equilibrium model for the selective sorption of gold cyanide on different ion-exchange functional groups

Ion exchange resins are still not used commercially for gold extraction fro m leached pulps despite the many advantages of ion exchange resins over act ivated carbon. This is a result of the poor understanding of the chemistry involved and a lack of a rigorous method of modelling, design and scale-up. The present study describes a theoretical model based on the principles of statistical thermodynamics as well as the Metropolis Monte Car-lo ((MMC) n umerical method that has been proposed previously to describe multi-compone nt sorption equilibria, An important aspect of this modelling approach is t hat it does nor use any solely empirical parameters. All parameters used de scribe only a single characteristic of the sorption system. It is therefore possible to include fundamental information of the system in order to faci litate easier parameter estimation, The model explicitly describes in a mat hematical form classical non-ideal sorption phenomena such as selectivity, irreversibility and interaction between sorbed species which previously hav e only been understood from a chemical viewpoint The model has been used to successfully describe the multicomponent equilibrium sorption of gold cyan ide and copper cyanide onto ion exchange resins containing different alipha tic amino groups. Consequently, by varying the surface properties and compa ring the model predictions with experimental data, further insight has been gained into the sorption properties of ion exchange resins for metal cyani de complexes. (C) 2000 Elsevier Science Ltd. All rights reserved.