Recovery of iron and lead from a secondary lead smelter matte by magnetic separation

A secondary Pb smelter matte containing ca. 50 wt.% Fe (as FeS, Fe3O4, FeO and metallic Fe), shows good potential for being used as a secondary Fe source. However, requirements for Fe ore are: Fe content >60% and absence of sulphide phases. Therefore, further pre-treatment steps are necessary to increase the Fe content in the matte. Dry low intensity, wet low intensity and wet high intensity magnetic separation experiments were performed on different particle size fractions of the matte. Mineral liberation analysis (MLA) was performed to explain different behaviour of Pb in the different size fractions during magnetic separation. Moreover, oxidizing roasting at 600°C was performed to transform FeS to Fe2O3. Results show that by combining low and high intensity magnetic separation and oxidizing roasting, material containing up to 61 wt% Fe (as oxide) can be recovered in the magnetic fraction representing circa 50% of the initial weigth of the sample.