Application of Response Surface Methodology (RSM) for Simultaneous Optimization of Kinetic Parameters Affecting Gold Leaching in Thiosulfate Based Media: A Statistical Approach

Abstract

Over the years, the use of new alternative lixiviants for gold extraction has been investigated to overcome the environmental concerns resulting from the cyanidation process. Moreover, with global economic factors causing a decline in gold prices, it is crucial that novel hydrometallurgical methods of extracting gold minimise operational costs by using low-priced reagents such as thiosulfate. In the current study, the response surface methodology (RSM) approach is used to optimize the kinetic factors (temperature and copper, ammonia, and thiosulphate concentration) affecting gold leaching. Gold ore assayed at 16 g/t was characterized through X-ray fluorescence and X-ray diffraction spectrometric analysis as well as scanning electron microscope-energy dispersive spectrometric technique. Gold ore was predominantly siliceous with minor pyritic content. The results indicate a strong relationship between the actual gold leaching recovery data and the RSM model. Correlation coefficients R2 and adjusted R2 are equivalent to 0.9869 and 0.9817. Gold leaching in copper-ammonia-thiosulfate media is best described as a surface chemical reaction-controlled process, suggesting that gold dissolution in thiosulfate is considerably affected by the increase in temperature. The effect of temperature is mostly significant, contributing up to 64.65% of the gold recovery response model. The contribution percentages of the effects of time, thiosulfate [S2O3], ammonia [NH3], and copper [Cu] concentrations were calculated as 12.81%, 5.88%, 5.19%, and 4.65%, respectively. All investigated kinetic parameters were found statistically significant with p value <0.05. The optimal concentrations of gold leaching media to achieve potentially complete dissolution of gold from its ore in copper-ammoniacal thiosulphate media based on the effect of the investigated parameters were 0.5 M S2O3, 3 M NH3, and 0.003 M Cu2+ with a desirability value equivalent to unity (d = 1.000).

Investigation of the Combined Use of Diesel and CNG Fuels on an Hcci Engine Using Response Surface Methodology (Rsm)

“…For the variable parameters, CNG ratio, thermal efficiency, COV imep , CA50, combustion duration, UHC, NO x and smoke values are significant, but not significant for other response parameters. [39,40].…”

Una Comparación de Reactivos Alternos al Cianuro como Lixiviantes del Oro: Una revisión

“…Se han definido tres criterios importantes para considerar la efectividad de un lixiviante adecuado para el oro, estos son: bajo costo, baja toxicidad y alta velocidad de reacción (Gos & Rubo, 2001). Algunos de los reactivos más estudiados para la disolución del oro son la glicina (Garza-Román et al, 2021); mezclas de halógenos/halogenuros (La Brooy et al, 1994); compuestos derivados del azufre como el tiosulfato (Baloyi et al, 2022), la tiourea (Borda & Torres, 2022) y el tiocianato (Azizitorghabeh et al, 2021); así como el lixiviante por excelencia de minerales de metales preciosos, el cianuro (Marsden & House, 2006).…”

“…En esta reacción, el oro se oxida a un estado de oxidación "+1", formando un complejo de tiosulfato de oro. El proceso es más rápido que la lixiviación con cianuro porque el tiosulfato es un agente oxidante más fuerte (Baloyi et al, 2022).…”