Study on separating of zinc and iron from zinc leaching residues by roasting with ammonium sulphate

• Zinc and iron were separated from zinc leaching residues via sulfates roasting and water leaching.
• Zinc ferrite was decomposed with ammonium sulfate.
• The extractions of zinc and iron were 92.63% and 2.04% respectively.
• The iron concentration of zinc enriched leachate is below 0.38 g/L.
• The content of iron from the leached residues is enriched to 45.84%.

The hydrometallurgical processes for zinc recycling from zinc leaching residues (ZLR) generate a huge volume of iron residues. Iron residues lead to serious losses of metal value and secondary pollution. Efficient separation of zinc and iron is an ideal idea for avoiding iron residues by control zinc and iron phase from ZLR. In this study, a novel process for separating zinc and iron present in ZLR is developed consisting of sulfates roasting and selective leaching. The extraction of zinc increased to 92.63% while iron decreased to 2.04%. Zinc was leached efficiently from ZLR for comprehensive recovery with iron concentration of zinc enriched leachate below 0.38 g/L, so that the effective separation of zinc and iron was achieved. The iron content from this new process was increased higher than 45% for a potential use as an iron-making material after the removing of lead, zinc and cadmium from the leached residue. The iron removal process and iron residues could be avoided in the hydrometallurgical process.

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