Low temperature electrolysis for iron production via conductive colloidal electrode

Abstract

The iron and steel industry has a history of environmental consciousness, and efforts are continually made to reduce energy consumption and CO₂ emissions. However, the carbothermic process limits the further reduction of green house gas emissions, and only marginal improvements can be expected. Here, a novel and environmentally friendly method about electrochemical reduction of Fe₂O₃ to produce Fe is introduced at a low temperature of 110 °C in alkaline solution. In the process, an electrical-ionic conductive colloidal electrode containing the electrochemically active species (Fe₂O₃ particles), the liquid electrolyte (NaOH solution), and a percolating electrical conductor (C network) has been successfully fabricated and utilized to produce Fe. The simultaneous percolation of electrons and ions effectively increases the area of the current collector, and enables the process to function at higher currents/rates. To enhance the faradic efficiency and energy efficiency in the electrolyzing process, a Ti plate, which has low catalytic activity toward H₂ evolution reaction, was selected as the current collector for the cathode, and Pt foil, which has high catalytic activity toward O₂ evolution reaction, was utilized as the anode. XRD results confirmed all Fe₂O₃ was reduced to Fe and Fe₃O₄. The research can potentially lead to Fe smelting by reducing an aqueous Fe₂O₃ colloidal electrode directly to Fe powder with no direct carbon emissions.