Naci Umut Duru
University of Nevada Reno, USA; E-mail: nduru@nevada.unr.edu
ABSTRACT. Mathematical modelling plays a central role in the interpretation of hydrometallurgical extraction processes. Laboratory experiments generate valuable information regarding the dissolution behaviour of minerals; however, meaningful interpretation of experimental results requires quantitative models capable of describing extraction kinetics. In this study, a non-linear kinetic model describing gold extraction by cyanide was developed using experimental column recovery data and parameter estimation through least-squares regression. Experimental recovery measurements obtained from column leach tests were fitted to an exponential extraction model expressed as, F(t) = K2 * [1 – exp (K1 * t)], where F represents fractional extraction, K1 is the kinetic rate constant, K2 represents the asymptotic maximum extraction, and t denotes time. Model parameters were estimated by minimising the sum of squared differences between experimental observations and model predictions using spreadsheet-based optimisation. The resulting model successfully reproduces the non-linear extraction behaviour observed in the experimental dataset and demonstrates the capability of exponential kinetic models to represent the rapid initial dissolution and subsequent asymptotic recovery typical of hydrometallurgical systems. Statistical validation of the fitted model gave squared correlation coefficient (R²) as 0.9904 and root mean square error (RMSE) as 0.0168 in fractional extraction units. Direct comparison with reaction-control and diffusion-control shrinking-core alternatives showed that the selected single-exponential model gave the lowest RMSE for this dataset, and residual analysis showed no persistent bias after the initial ore wetting period.
Key words: heap leach, column test work, reaction kinetics, process simulation.
DOI: https://doi.org/10.58903/MPIG2656
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