EARTH

[1801-09-04] Recovery of zinc from high iron-bearing zinc calcines by alkaline leaching and precipitation process

○Ning Peng¹, Bing Peng^1,2, XiaoBo Min^1,2, Hui Liu^1,2 (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman：Mayumi Ito（Hokkaido University)

Keywords:alkaline leaching, zinc calcines, zinc ferrite, zinc precipitation

A new method to recover zinc from high iron-bearing zinc calcines is developed. Zinc calcines was roasted to decompose zinc ferrite under the atmosphere of CO and CO₂, then the roasted product was leached with alkaline solutions, in which zinc was selectively leached and iron was remained in leaching residues. Zinc extraction is as high as 98% after leaching in 5mol/L NaOH at 1^oC for 6min. The leachate was purified using Na₂S and Pb, Cu was removed as sulfide precipitates. The zinc was recovered from purified zinc pregnant solutions by pH adjustments using spent electrolyte as neutralizers. Nearly 99% of zinc were recovered as zinc hydroxide, and zinc oxide with high purity and good crystal structure was obtained from the zinc hydroxide after roasting at 25^oC for 6min.