Abstract

The development of a kinetic model is essential for understanding and predicting the full-scale operation of chloride media leaching. For this purpose, a simplified kinetic model that incorporates leaching and oxidation reactions in a chloride medium has been developed and calibrated, using experimental conditions and results from the Codelco RT column leaching campaigns. The model assumes a continuous and vertical one-dimensional flow with negligible radial and vertical diffusive transport, making it suitable for column where the vertical length is much greater than the horizontal scale. The model solves differential equations that account for the mass balances of various components: acid, acid-consuming gangue, precipitated jarosite, sulfide minerals (pyrite, covellite, chalcocite, chalcopyrite, and bornite), oxidized copper mineral, dissolved oxygen, chloride ion, aqueous copper (Cu(I) and Cu(II)), and aqueous iron (Fe(II) and Fe(III)). A stoichiometric matrix for chemical reactions is a descriptive tool used to represent the interactions between aqueous and solid components, incorporating kinetic laws for leaching and oxidation reactions. The leaching kinetics are based on the particle-scale phenomenon also called "shrinking core model", while the oxidation kinetics are based on chloride-mediated electron exchanges between all aqueous species (Cu(I), Cu(II), Fe(II), Fe(III), and O2). The kinetic parameters for leaching and oxidation were calibrated by utilizing multiple time-measured variables and optimization algorithms. To model was validated with data from experiments conducted under various conditions, and predictive errors were compared against experimental errors. The calibrated kinetic model yielded favorable adjustments for the recovery of copper and iron, as well as the behavior of aqueous species.