Abstract
Zinc (Zn) is effectively used as a corrosion inhibitor for iron (Fe) steel products. In Uzbekistan, 60,000 tons of Zn coating tape on water pipes are discharged annually to replace Cu pipes. It is desirable to introduce high-purity iron scrap into the steel recycling process after the effective removal of Zn. The above Fe scrap dust supplied from Uzbekistan was characterized as a mixture of ZnO, ZnFe2O4, and Fe3O4. In the present work, the iron-oxidizing acidophile, Acidimicrobium ferrooxidans ICP, was inoculated into the bioleaching leachate of Fe scrap dust under the strongly acidic conditions at ambient temperature. After optimizing the initial pH and the pulp density of the dust, the leaching recovery of Zn was only 50%. However, the addition of activated carbon significantly improved the leaching recovery of Zn to more than 90% as well as a high selectivity of Zn over Fe. Activated carbon contributed to enhance the electron shuttle between ICP and Fe3O4 , which contributes to the equilibrium shift in acid dissolution of ZnFe2O4.