Recovery of iron from zinc calcines by reduction roasting and magnetic separation

A new method to recover iron from high iron-bearing zinc calcine was developed. Zinc ferrite (ZnFe2O4) in zinc calcine was decomposed to zinc oxide and magnetite after roasting under a reducing atmosphere at temperatures over 700 °C. A mineral dressing by magnetic separation was used to recover magnetite from the roasted products. The effects of the roasting temperature and magnetic induction intensity on the grade and recovery of iron were investigated. Ultrasonic treatment and mechanical milling played an important part in breaking the encapsulated magnetic phases before magnetic separation. The results show that iron recovery increases with roasting temperature and magnetic induction intensity, and ultrasonic treatment and mechanical milling promote the recovery of iron by 20% compared to the roasted zinc calcine subjected to magnetic separation at the same magnitude.

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► We separated iron from zinc calcine by magnetic roasting and separation.
► Mixture of CO and N2 was used as reducing agent.
► Decomposition of zinc ferrite significantly depends on roasting temperature.
► The optimal magnetic intensity is about 1160 Gs.
► The maximum recovery of iron reached to 64.2% under optimal conditions.