In order to develop a new, efficient industrial process for
producing high quality iron and steel with significantly reduced
carbon dioxide emissions, we investigated the electrowinning
of iron from an iron oxide ore in aqueous alkaline solutions.
Hematite (Fe2O3) solid particles suspended in the concentrated
aqueous sodium hydroxide (NaOH) solutions were transferred
to the cathode (e.g., a rotating disk graphite electrode) and
reduced to iron metal by applying a constant current; oxygen
was evolved on the anode (e.g., a nickel screen mesh). Current
efficiencies of above 90% with respect to iron deposition
were consistently obtained under the specific conditions in a
laboratory cell, and the corresponding energy consumptions
were calculated to be around 3 kWh·kg-1 iron. The deposited
iron crystals were the oriented clusters of stacked six-fold twins in
a tetrahedron-shape grew growing in a direction perpendicular
to the cathode surface. Influences of rotation rates of the cathode,
cathodic current densities, contents of the Fe2O3 particles
in electrolytes, and concentrations of NaOH solutions on
current efficiency and morphology of deposits were studied.