Ligand mediated eco-friendly leaching of zinc from spent catalyst in alkaline media

A novel leaching process for recovering Zn from spent catalyst in alkaline solution has been discussed. The catalyst was characterized for physico-chemical properties by chemical, XRD, TG-DTA and SEM. More than 92% Zn could be extracted from spent catalyst under the conditions: pulp density 2.5% (w/v), NaOH 1 M, EDTA 0.025 M, temperature 80 °C and time 3 h. Zn extraction increased with the number of stages. At the 4th stage almost all Zn could be extracted. A tentative process flow-sheet has been proposed based on Zn recovery. Characterization of leach residue by XRD and SEM gave an insight into the mechanism.