Experimental Study of the Sulphatizing Roasting of Flotation Tailings from Copper Slag Processing Using Iron Sulfates

The present study focuses on the experimental investigation of sulphatizing roasting of flotation tailings from copper slag processing using iron (II) and (III) sulfates followed by water leaching. The effect of temperature, duration of sulphatizing roasting, as well as the amount of iron sulfates on the conversion of zinc, copper, iron and other components in the tailings into water-soluble sulfate compounds were studied. The experiments have shown that there is no significant difference between using of both iron sulfates. The extraction degree after more than 20 min of the roasting varied in the approximate ranges of 50-70% for Zn, 45-70% for Cu and 0.01-10% for Fe. The best results were the extraction of 69.2% Cu, 62.8% Zn and 1.2% Fe obtained by 180 min of the roasting at 625°C with addition of 150% FeSO₄⋅7H₂O to 100% of the tailings. Based on the mineralogic and microstructure investigations of the samples, the assumptions were made for the reasons of the deficient extraction degrees of copper and zinc, as well as high sulphatizing agent consumption.