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.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
E.W. Thisted, Electrochemical Properties of Phosphorus Compounds in Fluoride Melts, PhD thesis, (Norwegian University of Science and Technology, 2003)
G.T. Holmes, Light Metals 1995, ed. J.W Evans, (Minerals, Metals & Materials Society, 1995), pp. 371–373
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
K. Grjotheim, Contribution to the Theory of the Aluminum Electrolysis, PhD thesis, (Norwegian University of Science and Technology, 1956)
R.J. Snow, and B.J. Welch, R.J. Snow, and B.J. Welch, J. Electrochem. Soc. 115, 1170. (1968).
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).
S. J. Lindsay, Proceedings of the 9th Australasian Aluminium Smelting Technology Conference, 2007, pp. 5-22
S. Lindsay and C. Dobbs, Light Metals 2006, ed. T.J. Galloway (Minerals, Metals & Materials Society, 2006), pp. 95–100
K. Grjotheim, and B. Welch, Aluminium Smelter Technology, 2nd edn. (Aluminum Verlag, Düsseldorf, 1988), pp 57–63
M. Sørlie, H. Øye, Cathodes in Aluminum Electrolysis, 3rd ed. (Aluminum Verlag, 2010), pp. 232–234, pp. 520–521
W.K. Fischer and R.C. Perruchoud, Light Metals 1991, ed. E. Rooy (Minerals, Metals & Materials Society, 1991), pp. 721–724
J.F. Grandfield, Fundamentals of Aluminum Metallurgy—Production, Processing and Applications, ed. Roger Lumley (Cambridge: Woodhead Publishing Ltd., 2011), section 5.10.4
M.B. Dell, Light Metals 1985, ed. H.A. Bohner (Warrendale, Pa.: Metallurgical Society of AIME, 1985), pp. 957–965
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
L. Dion, L. Kiss, P. Chartrand, G. Dufour and F. Laflamme, Light Metals 2013, ed. B.A. Sadler (Wiley, 2013), pp. 741–746
M. Graham and B. Pruitt, R&D for Industry: A Century of Technical Innovation at Alcoa, (New York: Cambridge University Press, 1990, p. 47
N. E. Richards, Alumina in Smelting, (11th International Course on Process Metallurgy of Aluminium, 1992), Chapter 10, p.3
K. Khaji and M. Al-Qassemi, Light Metals 2015, ed. M. Hyland (Springer, Cham, 2015), pp. 1135–1140
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
M. Iffert, Aluminum Smelting Cell Control and Optimisation, PhD thesis (University of New South Wales, 2008), pp. 124–133
A.T. Tabereaux, T.R. Alcorn and L. Trembley, Light Metals 1993, ed. S.K. Das (Minerals, Metals & Materials Society, 1993), pp. 221–226
A. Abbe, Light Metals 2009, ed. G. Bearne (The Minerals, Metals & Materials Society, 2009), pp. 529-532
W. Haupin, Properties of Bath, (11th International Course on Process Metallurgy of Aluminium, 1992), Chapter 5, p.15
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
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
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
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
E. Sturm and G. Wedde, Light Metals 1998, ed. B. Welch, (Minerals, Metals & Materials Society, 1998), pp. 235–240
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.
Conflict of interest
The authors declare that they have no conflicts of interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
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