Metallurgical and Materials Transactions B

, Volume 49, Issue 5, pp 2809–2820 | Cite as

Balancing Sodium Impurities in Alumina for Improved Properties

  • Hasini WijayaratneEmail author
  • Margaret Hyland
  • Grant McIntosh
  • Linus Perander
  • James Metson


As there are direct and indirect impacts of feed material purity on the aluminum production process and metal grade, there is a high demand on the so-called pure smelter grade alumina (SGA)—the main feedstock for aluminum production. In this work, impurities within the precursor gibbsite used for SGA production and SGA are studied using NanoSIMS and XPS with a focus on sodium—the most abundant impurity. Although the industry trend is towards minimizing sodium due to the well-known negative impacts on the process, high sodium is also correlated with relatively attrition-resistant calcined products. Here, we show that this relationship is indirect and arises from sodium’s role in inhibiting α-alumina formation. Alpha alumina formation in SGA has previously been demonstrated to induce a macro-porous and therefore attrition-prone microstructure. Sodium distribution within the precursor gibbsite and its migration during the calcination process are proposed to be most likely responsible for the spatial distribution of α-alumina within the calcined product grain. This in turn determines the behavior of the product during its transportation and handling (i.e., attrition). Therefore, tolerance of a certain amount of sodium within the precursor material does demonstrate a net benefit while balancing its negative impacts on the process.



The authors would like to acknowledge the generous support of Outotec GmbH. The assistance of Dr. Paul Guagliardo and Professor Matt Kilburn at UWA for NanoSIMS data collection and Reece Oosterbeek for XPS data collection are also acknowledged.

Supplementary material

11663_2018_1310_MOESM1_ESM.docx (11 kb)
Supplementary material 1 (DOCX 11 kb)


  1. 1.
    S.J. Lindsay: Light Metals, TMS, 2012, pp. 163–67.Google Scholar
  2. 2.
    S.J. Lindsay: Light Metals, TMS, 2005, pp. 117–22.Google Scholar
  3. 3.
    A.M. Taylor: 8th Australasian Aluminum Smelting Technology Conference and Workshops, Yeppon, Australia, 2004.Google Scholar
  4. 4.
    M. Authier-Martin, G. Forte, S. Ostap, and J. See: JOM, 2001, vol. 53, pp. 36-40.CrossRefGoogle Scholar
  5. 5.
    J.V. Sang: Essential Readings in Light Metals, Wiley, New York 2013, pp. 740–46.CrossRefGoogle Scholar
  6. 6.
    J.V. Sang: Essential Readings in Light Metals, Wiley, New York, 2013, pp. 592–601.CrossRefGoogle Scholar
  7. 7.
    L.T. Kristiansen, A.K. Prytz, and E. Tveten: Proceedings of the 9th International Alumina Quality Workshop, 2012, pp. 326–30.Google Scholar
  8. 8.
    A. Saatci, H.W. Schmidt, W. Stockhausen, M. Stroder, and P. Strum: Light Metals, TMS, 2004, pp. 81–86.Google Scholar
  9. 9.
    P. Clerin, and V. Laurent: Light Metals, TMS, 2001, pp. 41–47.Google Scholar
  10. 10.
    C.K. Matocha, and J.H. Hooks: Light Metals, TMS, 1987, pp. 875–79.Google Scholar
  11. 11.
    D.J. Braun: Light Metals, TMS, 1984, pp. 257–68.Google Scholar
  12. 12.
    W. L. Forsythe and W. R. Hertwig : Ind. Eng. Chem., 1949, vol. 41, pp. 1200-1206.CrossRefGoogle Scholar
  13. 13.
    H. Wijayaratne, G. McIntosh, M. Hyland, L. Perander and J. Metson : Metall. Mater. Trans. A, 2017, vol. 48A, pp. 3046-3059.CrossRefGoogle Scholar
  14. 14.
    F. Yen, P. Cheng, H. Huang, H, and T. Lin : J. Am. Ceram. Soc., 2009, vol. 92, pp. 2089-2092.CrossRefGoogle Scholar
  15. 15.
    S. Chandrashekar, D. Jackson, and J. Kisler: Proceedings of the 7th International Alumina Quality Workshop, 2005, pp. 5–9.Google Scholar
  16. 16.
    S.J. Lindsay: Light Metals, TMS, 2014, pp. 597–601.Google Scholar
  17. 17.
    S.J. Lindsay: Light Metals, TMS, 2011, pp. 163–68.Google Scholar
  18. 18.
    K. Wefers, and C. Misra: Oxides and Hydroxides of Aluminum, Alcoa Laboratories, Pittsburgh, 1987.Google Scholar
  19. 19.
    Y. Y. Park, S. O, Lee, T. Tran, S. J. Kim and M. J. Kim : Int. J. Miner. Process., 2006. vol. 80, pp. 126-132.CrossRefGoogle Scholar
  20. 20.
    L.M. Perander: Evolution of nano—and microstructure during the calcination of Bayer Gibbsite to produce Alumina, Ph.D. thesis, The University of Auckland, 2010.Google Scholar
  21. 21.
    H. Samarasekara: Phase distribution and properties of smelter grade alumina, Final Year Project Report, The University of Auckland, 2006.Google Scholar
  22. 22.
    K. Robertson, R. Gauvin, and J. Finch: Microsc. Microanal., 2004, vol. 10, pp. 721-732.CrossRefGoogle Scholar
  23. 23.
    T. C. Baroni, F. J. Lincoln, B. J. Griffin, J. B. Cornell and G. I. D Roach: Scanning, 2002, vol. 24, pp. 18-24.CrossRefGoogle Scholar
  24. 24.
    G. R. Watt, B. J. Griffin and P. D. Kinny: Am. Mineral., 2000, vol. 85, pp. 1784-1794.CrossRefGoogle Scholar
  25. 25.
    T. C. Baroni, B. J. Griffin, J. R. Browne, and F. J. Lincoln: Microsc. Microanal., 2000, vol. 6, pp. 49-58.Google Scholar
  26. 26.
    G.I. Roach, J.B. Cornell, and B.J. Griffin: Light Metals, TMS, 1998, pp. 153–58.Google Scholar
  27. 27.
    A. Sterten, P. A. Solli and E. Skybakmoen: J. Appl. Electrochem., 1998, vol. 28, pp. 781-789.CrossRefGoogle Scholar
  28. 28.
    E. Haugland, G.M Haarberg, E.Thisted, and J. Thonstad: Light Metals, TMS, 2001.Google Scholar
  29. 29.
    G. J. McIntosh, H. Wijayaratne, A. Chan, L. Perander and M. Hyland : Acta Materialia, 2018, vol. 153, pp. 226-234.CrossRefGoogle Scholar
  30. 30.
    N. I. Eremin, M. I. Cherepanova, N. S. Shmorgunenko and M. A. Maksakova: Sov. Non-Ferrous Metals Res., 1980, vol. 8, pp. 132-135.Google Scholar
  31. 31.
    N. I. Eremin, M. I. Cherepanova and M. A. Maksakova: Sov. Non-Ferrous Metals Res., 1980. vol 8, pp. 263-266.Google Scholar

Copyright information

© The Minerals, Metals & Materials Society and ASM International 2018

Authors and Affiliations

  • Hasini Wijayaratne
    • 1
    Email author
  • Margaret Hyland
    • 1
  • Grant McIntosh
    • 1
  • Linus Perander
    • 2
  • James Metson
    • 1
  1. 1.Light Metals Research CentreUniversity of Auckland, NewmarketAucklandNew Zealand
  2. 2.Outotec GmbHOberurselGermany

Personalised recommendations