Research on Recovery of Zinc as Zno from Waelz Oxide by Leaching with Nh4cl Solutions

Abstract

With the increasing shortage of zinc concentrate supply, the recovery of zinc from secondary resources has become the key issue to sustainable development. As the main intermediate product of secondary zinc resources, Waelz-fume has always been the focus of research. In this paper, a novel hydrometallurgical process for treating Waelz oxide is developed. The main steps include leaching Waelz oxide with NH 4 Cl solution, purifying the leachate by zinc cementation, and precipitating zinc as ZnO by adding CaO. The zinc extraction can reach 87.9% through NH 4 Cl leaching. More than 99.0% lead and cadmium can be removed by zinc cementation. Under optimal precipitation conditions, 96.6% of the zinc in the leachate can be precipitated as highly pure zinc oxide. The preliminary estimation shows that the process provides a cost-effective and environmentally feasible scheme for treating Waelz oxide with the potential advantages of little pollution, simple equipment, and convenient operation.

Keywords: Waelz oxide, ammonium chloride leaching, zinc cementation, Precipitation