Facile and complete sulfuric acid leaching of zinc ferrite assisted by copper powder: Leaching mechanism and kinetics investigation

[Display omitted] •Copper powder was very efficient on zinc ferrite leaching in a sulfuric acid solution.•Zinc ferrite was completely dissolved within 20 min at 60 ℃, or within 10 min at 80 ℃.•The minimum copper consumption was 27.15% of zinc ferrite.•The leaching process was controlled by surface chemical reaction.•Galvanic interaction between zinc ferrite and copper enhanced their dissolution. Zinc ferrite is a dominant phase in mass solid wastes generated from zinc or iron production, which causes the obstacle of metal recovery and recycling. A facile and efficient sulfuric acid leaching process of zinc ferrite assisted by copper powder was proposed in this study. The effects of factors on the leaching of zinc ferrite and copper were investigated. The results showed that zinc ferrite and copper were coupled and leached. The complete dissolution of zinc ferrite was obtained with wide ranges of leaching conditions. The shortest time for the complete dissolution of zinc ferrite was 10 min at 80 ℃ under the conditions: copper to zinc ferrite molar ratio of 1.5, sulfuric acid concentration of 100 g/L, liquid to solid ratio of 30 mL/g, and copper powder of + 38.5–20 μm. The least consumption of copper to realize the complete dissolution of zinc ferrite was 27.15%. The leaching kinetics was studied by the shrinking core model. It was found that zinc ferrite leaching assisted by copper was controlled by surface chemical reaction. The apparent activation energies for zinc, iron, and copper are 56 kJ/mol, 56 kJ/mol, and 50 kJ/mol, respectively. Characterization of the leaching residues and determination of iron and copper species in the leaching solution showed galvanic corrosion took place between zinc ferrite and copper, enhancing their acid dissolution.