Influence of Texture and Trace Element Composition on Hematite to Wüstite Reduction Rates of Fine Iron ore Fragments

Abstract

Reduction of ore is the key process in its conversion to the metal form, and the reducibility of ore fragments is therefore a crucial parameter in smelting operations. At constant oxygen fugacity, reducibility is controlled by the texture of the ore fragments, which determines the transport length from reduction front to fragment interface, and the chemistry of the ore fragments, which impacts element mobility within the crystal lattice. Their relative contribution was studied here for iron-ore reduction by combining compositional analyses and thermo-gravitational reduction experiments on individual ore fragments. Results indicate that despite large, and ore-characteristic differences in chemistry, ore-fragment composition has a negligible impact on reducibility. The large variations among bulk ores; e.g. the start of hematite-to-magnetite reduction varies by over 300°C, is therefore attributable to ore-texture effects. Porous, goethite-dominated ores show the highest reducibility, followed by fractured and layered fragments and finally dense ore fragments.