Optimization of Leaching Parameters and Kinetic Modelling for Leaching of Zinc from Zarara Hill Sulphide Ore in Different Acid Solutions

Abstract

This research focused on optimization and kinetics of zinc dissolution from Zarara Hill sulphide ore using HNO3, HCl and H2SO4. A polymetallic sulphide ore collected from Zarara hill, Kaduna State, Nigeria, was used for this study. The result of elemental analysis of the powdered sulphide ore using ICP-OES technique indicate that the major elements detected are Fe, Zn, Cu, Pb and S while the minor elements include Co, Ni, Mo, and Cd. Response Surface Methodology (RSM) was employed to model, optimize and evaluate the effects and interactions of the influential parameters on the recovery of zinc using HNO3, HCl and H2SO4. From the output proposed by the Design-Expert software, the quadratic model was not aliased. In order to fit a good model, a test for significance of the regression model and individual model coefficients with lack of fit test was performed. The significant factors were ranked based on P-value (probability value) with 95% confidence level. The smaller ‘P’ values from the ANOVA generated for both HNO3, HCl and H2SO4 show more significant of the corresponding coefficients. All the R-squared values are close to one and each of the adjusted R-squared values are close to its corresponding R-square value. These confirm the adequacy of the developed model. Dissolution kinetics, studies shows that the order of reaction concerning H+ ion concentration for zinc dissolution using HCl, H2SO4 and HNO3 were 0.53, 0.58 and 0.54 respectively. And from Arrhenius plot the activation energy were calculated to be 24.3, 22.8 and 21.2 kJmol-1 for HCl, H2SO4 and HNO3 dissolutions respectively.