Optimization of Influential Factors in Gold Electrowinning using Response Surface Methodology

Electrowinning is the extraction of metals from aqueous solution. The effects of three main factors namely temperature, caustic strength and current density on gold electrowinning were studied in order to obtain high electrowinning efficiency. Response surface methodology, in combination with central composite face-centered design (RSM-CCF), was used to fit the model and ridge analysis to optimize the selected factors. A series of 17 experiments arranged in a CCF design was carried out and the results fitted using ordinary least squares (OLS) method. Findings confirmed that the effect of caustic strength was found to be the most influential of the three factors followed by temperature and current density. For deposition of gold in the circuit current density was also vital. The average electrowinning efficiency at 683, 750 and 800 A/m2 are 77, 82.1 and 86.2 % respectively. Mathematical model was constructed to characterise the electrowinning efficiency. From the model, optimal ranges obtained were caustic strength of 2.28 - 2.43 %, current density of 784.50 797.00 Am-2 and temperature of 46.70 49.50.