Study of Sulphatizing Roasting Process Using Iron Sulphates for the Treatment of Zinc Leach Residue

The paper presents the results of the investigation of zinc leach residue (ZLR) processing by sulphatizing roasting with iron sulphates FeSO4 and Fe2(SO4)3 followed by water leaching. The elemental and phase compositions of ZLR of JSC "Chelyabinsk Zinc Plant" were studied. Based on the thermodynamic calculations using HSC Chemistry 9.9 software, the temperature ranges of the sulphatizing roasting and the required amounts of iron sulphate additives for the sulphation of zinc and copper were determined. Subsequent experiments showed that recovery rates of zinc and copper reached 99.5% and 89.1% respectively, while iron remained in the leached residue. The results have indicated a high efficiency of sulphatizing roasting to transform zinc and copper contained in ZLR from ferrite to water-soluble sulphate.