Kinetic Aspects of Leaching Zinc from Waste Galvanizing Zinc by Using Hydrochloric Acid Solutions

In this work, the results of acid leaching of flux skimmings coming from two plants are presented. Sample A contained two phases, Zn(OH) Cl and NH4Cl. In sample B, the presence of three phases, Zn-5(OH)(8)Cl-2.H2O, (NH4)(2)(ZnCl4) and ZnCl2(NH3)(2), was proved. The aqueous solution of hydrochloric acid and distilled water was used as the leaching medium. The effects of the leaching time, temperature and concentration of the leaching medium on the zinc extraction were investigated. The apparent activation energy, E-a = 4.61 kJ mol(-1), and apparent reaction order n = 0.18 for sample A, and the values E-a = 6.28 kJ mol(-1) and n = 0.33 for sample B were experimentally determined. Zinc leaching in acid medium is a diffusion-controlled process.