Electrowinning of Iron in Aqueous Alkaline SolutionUsing Rotating Disk Electrode

Abstract

In order to develop a new, efficient industrial process forproducing high quality iron and steel with significantly reducedcarbon dioxide emissions, we investigated the electrowinningof iron from an iron oxide ore in aqueous alkaline solutions.Hematite (Fe₂O₃) solid particles suspended in the concentratedaqueous sodium hydroxide (NaOH) solutions were transferredto the cathode (e.g., a rotating disk graphite electrode) andreduced to iron metal by applying a constant current; oxygenwas evolved on the anode (e.g., a nickel screen mesh). Currentefficiencies of above 90% with respect to iron depositionwere consistently obtained under the specific conditions in alaboratory cell, and the corresponding energy consumptionswere calculated to be around 3 kWh·kg^-1 iron. The depositediron crystals were the oriented clusters of stacked six-fold twins ina tetrahedron-shape grew growing in a direction perpendicularto the cathode surface. Influences of rotation rates of the cathode,cathodic current densities, contents of the Fe₂O₃ particlesin electrolytes, and concentrations of NaOH solutions oncurrent efficiency and morphology of deposits were studied.