Quantitative Leaching of Spent Galvanized Zinc Ash by Hydrochloric Acid

Abstract

Leaching is an extractive metallurgy technique widely used in converting metal into soluble salt in aqueous media. In this study, experiments on quantitative leaching of spent galvanized zinc ash in hydrochloric acid solution were examined. Experimental parameters such as acid concentration and reaction temperature were varied. In addition, reaction residues at optimal leaching were examined by scanning electron micrography (SEM) and the products of reaction were identified by energy dispersive X-ray (EDXRF) and X-ray diffraction (XRD). The leaching results showed that the amount of zinc ash powder dissolved increases with increasing acid concentration and temperature. At optimal conditions (4 mol/L HCl, 75°C, 0.1mm), the dissolution reached 98.5% within 120 minutes. Also, the leaching results conform to a rate limiting diffusion controlled reaction. The calculated activation energy of 25.96 kJ/mol is reasonable for a rate limiting surface reaction and supported the proposed dissolution mechanism.