Innovative methodology for comprehensive utilization of high iron bearing zinc calcine

•Comprehensive utilization of zinc calcine by novel method is feasible.•ZnFe2O4 was converted selectively to ZnO and Fe3O4 by reduction roasting with CO.•About 91% Zn was extracted selectively from roasted zinc calcine by acid leaching.•More than 90% Fe could be recovered from leach residue by magnetic separation.•Lead impurity was separated and concentrated to final tailing as PbSO4 and Pb.

An innovative method for comprehensive utilization of high iron bearing zinc calcine was proposed, and the recovery of zinc and iron was studied. The thermodynamic analysis and roasting experiments were firstly carried out to study the decomposition of ZnFe2O4 which could be selectively converted to ZnO and Fe3O4 under optimized roasting conditions. The roasted zinc calcine was then subjected to low acid leaching followed by magnetic separation. The effects of operating conditions on the recovery of zinc and iron and the mineralogical changes during the process were investigated. The results showed that about 91% of zinc was extracted and most of iron was separated into the leach residue as magnetite at 40 °C for 10 min with 90 g/L H2SO4 and liquid/solid ratio at 10 mg/L, while about 91% of iron was reported to the concentrate with iron grade of 45.5% after a magnetic separation at 35 kA/m. Besides, lead impurity was transformed, separated and concentrated into the tailing in the form of PbSO4 and Pb.