Production of Fe metal from Fe ores through novel molten oxide electrolysis at 1173 K

To develop a CO 2 -free process for the direct production of Fe from Fe ore, the molten oxide electrolysis (MOE) of Fe oxides and ores was investigated in a B 2 O 3 – Na 2 O molten oxide at 1173 K. Thermodynamic calculations and cyclic voltammetry measurements were performed to identify the electrochemical reduction behavior of the selected oxides. In addition, electrolysis was conducted by applying a cell voltage of 1.6 V in air or Ar gas atmosphere. When electrolysis was carried out in air, current efficiencies ranging from 65.50 – 68.72% were obtained, depending on the type of Fe oxide used, whereas electrolysis in an Ar gas atmosphere showed higher current efficiencies of 67.49 – 78.56% owing to the suppressed re-oxidation of reduced Fe under a low p O2 . Furthermore, electrolysis using hematite, goethite, and magnetite in air produced Fe metal with current efficiencies of 64.14%, 66.00%, and 67.58%, respectively. These results demonstrated the feasibility of the low-temperature MOE of Fe ores in a B 2 O 3 – Na 2 O molten oxide for direct and CO 2 -free production of Fe.