Effect of mechanical activation on dissolution kinetics of neutral leach residue of zinc calcine in sulphuric acid
(1. School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China;2. Guangxi Research Institute of Chemical Industry, Nanning 530001, China;3. Department of Chemistry and Biology, Hechi College, Yizhou 546300, China)
Abstract: Neutral leach residue of zinc calcine (NLRZC) was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation (MA) induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H2SO4 concentration were found to be 0.34, 0.30, and 0.29, respectively.
Key words: zinc; dissolution kinetics; mechanical activation; neutral leach residue