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Impacts of Sodium on Alumina Quality and Consequences for Current Efficiency

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Light Metals 2018 (TMS 2018)

Part of the book series: The Minerals, Metals & Materials Series ((MMMS))

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Abstract

Current and energy efficiency during primary aluminium production are negatively impacted by incomplete fluoride return and high levels of α-Al2O3. We propose that residual sodium within smelter grade aluminas can have indirect but potentially profound impacts on efficiency by influencing both fluoride return and α-Al2O3 content. We demonstrate that sodium originally intercalated in gibbsite becomes incorporated in the bulk alumina structure on calcination, segregating in the internal porosity as it moves toward the grain exterior. First, this segregation can partially block some of the narrower porosity, consequently lowering specific surface area. This is demonstrated to lower the HF scrubbing capacity and consequently fluoride return, thereby negatively impacting process efficiency. On the other hand, sodium incorporated in the bulk inhibits conversion to α-Al2O3, having a potentially significant positive impact on current efficiency.

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Authors and Affiliations

  1. School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand

    Grant J. McIntosh & James B. Metson

  2. Light Metals Research Centre, The University of Auckland, Private Bag 92019, Auckland, New Zealand

    Grant J. McIntosh, Hasini Wijayaratne, Gordon E. K. Agbenyegah, Margaret M. Hyland & James B. Metson

  3. Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland, New Zealand

    Hasini Wijayaratne, Gordon E. K. Agbenyegah & Margaret M. Hyland

Authors
  1. Grant J. McIntosh
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  2. Hasini Wijayaratne
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  3. Gordon E. K. Agbenyegah
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  4. Margaret M. Hyland
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  5. James B. Metson
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Corresponding author

Correspondence to Grant J. McIntosh .

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Editors and Affiliations

  1. Rio Tinto Alcan, Saint Jean, France

    Olivier Martin

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© 2018 The Minerals, Metals & Materials Society

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McIntosh, G.J., Wijayaratne, H., Agbenyegah, G.E.K., Hyland, M.M., Metson, J.B. (2018). Impacts of Sodium on Alumina Quality and Consequences for Current Efficiency. In: Martin, O. (eds) Light Metals 2018. TMS 2018. The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-319-72284-9_70

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