Modelling and simulation of gold thiosulphate elution in ammoniacal thiosulphate resin solution system

Abstract

The gold thiosulphate complex and gold thiosulphate–sulphite complex are formed in the adsorption and elution of gold thiosulphate in ammoniacal thiosulphate resin solution (ATRS) systems. This work proposed a mathematical model of gold thiosulphate elution based on mechanistic approach to predict the gold thiosulphate concentration along bed volumes. Adsorption experiment was conducted to highlight the charge distribution for thiosulphate, trithionate and gold thiosulphate adsorbed on resin at equilibrium. The proposed model was simulated to demonstrate the effect of parameter on the GTC and GTSC concentration in elution. Multivariable optimization approach was taken into account to obtain an optimal value of the GTC and GTSC elution parameters. As the results, the optimal anion exchange coefficients of GTC and GTSC elution were worked out becoming approximately 2.4E-04 and 1.5E-04 m2/s, respectively, with the optimal percentile of occupied sites for the GTC and GTSC being approximately 4.06 and 8.15%, respectively, for 0.2 M trithionate with the absence and presence of sulphite, respectively. Overall, the model-based results were in very good agreement with the results based on experimental data referenced with the correlation coefficient (R2 is approximately 0.9 and 0.94 for the GTC and GTSC, respectively).