Journal of Applied Electrochemistry

, Volume 38, Issue 10, pp 1401–1407 | Cite as

Mechanistic investigation into the electrolytic formation of iron from iron(III) oxide in molten sodium hydroxide

  • A. Cox
  • Derek J. Fray
Original Paper


Iron(III) oxide tablets were electrolytically reduced to iron in molten sodium hydroxide at 530 °C and recovered to produce iron with 2 wt.% oxygen suitable for re-melting. The cell was operated at 1.7 V and an inert nickel anode was used. The thermodynamics and mechanism of the process was also investigated. By controlling the activity of sodium oxide in the melt, the cell could be operated below the decomposition voltage of the electrolyte with the net sequence of events being the ionization of oxygen, its subsequent transport to the anode and discharge leaving behind iron at the cathode. A reduction time of 1 h was achieved for a 1 g oxide tablet (close to the theoretical reduction time predicted by Faraday’s laws) at a current density of 520 mA cm−2 with iron phase yields of ∼90 wt.%. The energy consumption was 2.8 kWh kg−1.


Molten salt Sodium hydroxide Electro-deoxidation Iron Inert anode 



The authors are grateful to the EPSRC for funding (Platform Grant GR/S58447/01) the work in this project.


  1. 1.
    Industries (2006) E.C.o.I.a.SGoogle Scholar
  2. 2.
    Chen GZ, Fray DJ, Farthing TW (2000) Nature 407:361–364CrossRefGoogle Scholar
  3. 3.
    Burheim OS (2005) Institutt for Material Teknologi, University of TrondheimGoogle Scholar
  4. 4.
    Plambeck JA (1976) Encyclopedia of electrochemistry of the elements. Marcel DekkerGoogle Scholar
  5. 5.
    Newell LC (1904) Descriptive chemistry. HeathGoogle Scholar
  6. 6.
    Tremillon B (1971) Pure Appl Chem 25:395CrossRefGoogle Scholar
  7. 7.
    Schwandt C, Fray DJ (2005) Electrochimica Acta 51:66–76CrossRefGoogle Scholar
  8. 8.
    Yan XY, Fray DJ (2005) J Electrochem Soc 152:D12–D21CrossRefGoogle Scholar
  9. 9.
    Bouaziz R, Papin G, Rollet AP (1966) C R Acad Sci Ser C 262:1053Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Department of Materials Science and MetallurgyUniversity of CambridgeCambridgeUK

Personalised recommendations