Comparing strategies for iron enrichment from Zn- and Pb-bearing refractory iron ore using reduction roasting-magnetic separation

Abstract

Iron in refractory iron ore composed of 47.04% Fe, 0.39% Pb and 0.30% Zn was enriched through reduction roasting followed by magnetic separation in this work. The phase transformations occurring in iron ore during reduction roasting were investigated through XRD, VSM, and SEM-EDS. Results show reduction process of hematite follows Fe2O3 → Fe3O4 → FeO → Fe. The quartz in iron ore reacts with FeO to form fayalite. At elevated temperatures, fayalite decomposes into metallic iron and cristobalite solid solution. The reductively roasted product (RRP) with main phases of magnetite and metallic iron has higher magnetization intensity than that with main phases of wustite and fayalite. Iron in RRP-800 °C and RRP-1150 °C is extracted by magnetic separation, and obtained concentrates have main minerals of magnetite and metallic iron, respectively. Elevated temperature decreases zinc and lead contents in concentrate. Thus, deep reduction-magnetic separation is more suitable for enriching iron from Zn- and Pb-bearing refractory iron ore.