Selective Leaching of Zn from ZnFe2O4 Modified by CaO in the H2SO4 Solution

Zinc mainly exists in the form of ZnFe2O4 in steelmaking dust. Due to the stable properties of ZnFe2O4, the wet separation and recovery of Zn from steelmaking dust were generally conducted by using strong acid or alkali. To selectively separate Zn from ZnFe2O4 in a low-cost way, ZnFe2O4 was first modified by CaO at high temperature and then leached in the dilute H2SO4 solution. The effects of leaching conditions on the Zn selective leaching were investigated in this study. Due to the transformation of ZnFe2O4 into ZnO and Ca2Fe2O5 by CaO modification, the dissolution of Zn was significantly improved, and its dissolution ratio exceeded 90% at pH 2. Increasing temperature had little improvement in the leaching of Zn, but the Fe dissolution ratio obviously decreased at 60 degrees C due to ferric hydroxides precipitation. When the solid-to-liquid ratio increased to 1:50, approximately, 90% of Zn was leached from the modified ZnFe2O4 and the dissolution ratios of Ca and Fe lowered. A good selective leaching of Zn was achieved in the dilute H2SO4 solution. [GRAPHICS] .