A Review: Understanding the Science and the Impacts of Impurities upon the Electrolytic Bath of Hall–Héroult Reduction Cells

Abstract

The aim of this article is to present an overview of impurities of alkali metals and alkaline earth elements included in smelter-grade alumina and other raw materials that primarily report to the electrolyte, i.e., bath, and to suggest pathways for improved control at primary aluminum smelters. Comments are included on how these impurities affect intermediate subprocesses, metal products, and cell condition. The authors have worked to create a reference that not only reports on the scientific aspects of how impurities react in a bath of molten salt under electrolysis but also covers the practical matters of concern regarding impurities that affect the electrolyte. By combining scientific knowledge with process engineering techniques, readers should be able to better manage impurities and related impacts in aluminum production processes.

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adapted from Tingle et al.3).

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adapted from Dworkin et al.6).

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References

  1. 1.

    E.W. Thisted, Electrochemical Properties of Phosphorus Compounds in Fluoride Melts, PhD thesis, (Norwegian University of Science and Technology, 2003)

  2. 2.

    G.T. Holmes, Light Metals 1995, ed. J.W Evans, (Minerals, Metals & Materials Society, 1995), pp. 371–373

  3. 3.

    W.H. Tingle, J. Petit and W.B. Frank, Proceedings of the Symposium on Molten salts, Electrochemical Society Meeting, Washington, D.C., May 2–7, 1976

  4. 4.

    K. Grjotheim, Contribution to the Theory of the Aluminum Electrolysis, PhD thesis, (Norwegian University of Science and Technology, 1956)

  5. 5.

    R.J. Snow, and B.J. Welch, R.J. Snow, and B.J. Welch, J. Electrochem. Soc. 115, 1170. (1968).

    Article  Google Scholar 

  6. 6.

    A.S. Dworkin, H.R. Bronstein, and M.A. Bredig, A.S. Dworkin, H.R. Bronstein, and M.A. Bredig, Phys. Chem. 66, 572. (1962).

    Article  Google Scholar 

  7. 7.

    S. J. Lindsay, Proceedings of the 9th Australasian Aluminium Smelting Technology Conference, 2007, pp. 5-22

  8. 8.

    S. Lindsay and C. Dobbs, Light Metals 2006, ed. T.J. Galloway (Minerals, Metals & Materials Society, 2006), pp. 95–100

  9. 9.

    K. Grjotheim, and B. Welch, Aluminium Smelter Technology, 2nd edn. (Aluminum Verlag, Düsseldorf, 1988), pp 57–63

    Google Scholar 

  10. 10.

    M. Sørlie, H. Øye, Cathodes in Aluminum Electrolysis, 3rd ed. (Aluminum Verlag, 2010), pp. 232–234, pp. 520–521

  11. 11.

    W.K. Fischer and R.C. Perruchoud, Light Metals 1991, ed. E. Rooy (Minerals, Metals & Materials Society, 1991), pp. 721–724

  12. 12.

    J.F. Grandfield, Fundamentals of Aluminum Metallurgy—Production, Processing and Applications, ed. Roger Lumley (Cambridge: Woodhead Publishing Ltd., 2011), section 5.10.4

  13. 13.

    M.B. Dell, Light Metals 1985, ed. H.A. Bohner (Warrendale, Pa.: Metallurgical Society of AIME, 1985), pp. 957–965

  14. 14.

    P. Rafiei, F. Hiltmann, M. Hyland, B. James and B. Welch, Light Metals 2001, ed. J.L. Anjier (Minerals, Metals & Materials Society, 2001), pp. 747–752

  15. 15.

    L. Dion, L. Kiss, P. Chartrand, G. Dufour and F. Laflamme, Light Metals 2013, ed. B.A. Sadler (Wiley, 2013), pp. 741–746

  16. 16.

    M. Graham and B. Pruitt, R&D for Industry: A Century of Technical Innovation at Alcoa, (New York: Cambridge University Press, 1990, p. 47

  17. 17.

    N. E. Richards, Alumina in Smelting, (11th International Course on Process Metallurgy of Aluminium, 1992), Chapter 10, p.3

  18. 18.

    K. Khaji and M. Al-Qassemi, Light Metals 2015, ed. M. Hyland (Springer, Cham, 2015), pp. 1135–1140

  19. 19.

    J.B. Metson, D.S. Wong, J.H. Hung and M.P. Taylor, Light Metals 2013, ed. B.A. Sadler, (The Minerals, Metals & Materials Series. Springer, Cham, 2013), pp. 9–13

  20. 20.

    M. Iffert, Aluminum Smelting Cell Control and Optimisation, PhD thesis (University of New South Wales, 2008), pp. 124–133

  21. 21.

    A.T. Tabereaux, T.R. Alcorn and L. Trembley, Light Metals 1993, ed. S.K. Das (Minerals, Metals & Materials Society, 1993), pp. 221–226

  22. 22.

    A. Abbe, Light Metals 2009, ed. G. Bearne (The Minerals, Metals & Materials Society, 2009), pp. 529-532

  23. 23.

    W. Haupin, Properties of Bath, (11th International Course on Process Metallurgy of Aluminium, 1992), Chapter 5, p.15

  24. 24.

    E. Haugland, G.M. Haarberg, E. Thisted and J. Thonstad, Light Metals 2001, ed. J.L. Anjier (Minerals, Metals & Materials Society, 2001), pp. 549–553

  25. 25.

    P.A. Solli, T. Haarberg, T. Eggen, E. Skybakmoen and Å. Sterten, Light Metals 1994, ed. U. Mannweiler (The Minerals, Metals & Materials Society, 1994), pp. 195–203

  26. 26.

    J.A. Al-Mejali, G.M. Haarberg, N. Bensalah, B.A. Benkahla and H.P. Lange, Light Metals 2016, ed. E. Williams (Springer, Cham, 2016), pp. 389–394

  27. 27.

    A. Tabereaux, Phosphorus Impurity in Aluminum Electrolysis Cells, (TMS Course - Smelter Grade Alumina from the Smelting Perspective, 2004), Charlotte, N.C., Chapter 2, pp. 1–13

  28. 28.

    E. Sturm and G. Wedde, Light Metals 1998, ed. B. Welch, (Minerals, Metals & Materials Society, 1998), pp. 235–240

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Acknowledgements

We thank Nik Winjum and Les Edwards for their support in the preparation of this article. We are also grateful to Merino, Margarita R. (Ph.D. – Florida State University) for her encouragement, dedication, and support.

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Lindsay, S.J., Welch, B.J. A Review: Understanding the Science and the Impacts of Impurities upon the Electrolytic Bath of Hall–Héroult Reduction Cells. JOM (2021). https://doi.org/10.1007/s11837-021-04572-7

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