Separation of Iron from Zinc Calcine by Magnetic Roasting and Dressing

A novel technological routine for iron separation from high ironbearing zinc calcine was proposed. The zinc ferrite (ZnFe2O4) in zinc calcine was decomposed to zinc oxide and magnetite under reduction atmosphere at temperature over 800 degree C. The magnetic dressing was carried out to separate magnetite from reduction roasting products. The effects of roasting temperature, roasting time and magnetic intensity on grade and recovery of iron were investigated and the results showed that roasting temperature had a significant impact on iron recovery. In addition, ultrasonic dispersion and mechanical milling were performed to break the structure of the magnetic phases and non magnetic phases before magnetic dressing. The results indicated that ultrasonic dispersion could improve the iron recovery while mechanical milling could increase the grade of iron in concentrates. More than 80% of iron was recovered by using the optimal magnetic roasting and dressing.