P.A. Kempler, A.C. Goldman, R. Shekhar, A. Konovalova, E. Rahman
University of Oregon,
United States
Keywords: direct oxide reduction, electrolysis, electrowinning, iron
Summary:
The scalability of low temperature cells for iron ore electrolysis may be constrained by reactor throughput and the availability of acceptable feedstocks. Electrodes directly converting solid iron-oxide particles to metal circumvent traditional mass-transport limitations but are sensitive to both the particle size and nanoscale morphology of reactants. In this talk, we will present electrolysis data for size-controlled, homologous ⍺-Fe2O3 particles and discuss how nanoscale morphology influences the obtainable current density towards Fe metal. We observe apparent limiting current densities < 0.1 A cm–2 for fully dense iron-oxide particles but find that micron-scale ⍺-Fe2O3 with nanoscale porosity can be used to form Fe at current densities commensurate with industrial water electrolysis (> 0.6 A cm-2) in the absence of external convection. Results from a small-scale electrowinning cell were integrated into a technoeconomic model for both chlor-iron systems and alkaline iron electrowinning systems to identify key process parameters for research and development. We find that at present-day electricity prices and realistic cell resistances, ironmaking economics are sensitive to the operating current density and identify optimum current densities for operation over thousands of model scenarios.