The Impact of Alumina Quality on Current Efficiency and Energy Efficiency in Aluminum Reduction

McIntosh, Grant J.; Metson, James B.; Lavoie, Pascal; Niesenhaus, Thomas; Reek, Till; Perander, Linus

doi:10.1002/9781119274780.ch68

Cited by 2 publications

(3 citation statements)

References 9 publications

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“…We have also linked this to energy efficiency. 6 This indicates that the BET SSA, as reported on alumina specification sheets, is not ideal in predicting scrubbing or fluoride return efficiency, as this method necessarily includes this small pore surface area. Rather, the authors advocate a BJH-based estimate, requiring PSD knowledge, where pores £3.5 nm are explicitly omitted from the surface area.…”

Section: Resultsmentioning

confidence: 99%

“…6 In these studies, data from a wide range of smelter parameters were assimilated into 572-point-long vectors, one vector for each parameter. Each data point in a vector represents a daily mean value of that parameter, and was obtained after averaging over 24 h of observation per cell, and further averaged over 60 cells running a common alumina.…”

Section: The Impact Of Alumina Pore Size On Fluoride Balances In An Omentioning

confidence: 99%

“…[1][2][3][4][5] Additionally, fluctuations in fluoride level are associated with losses in cell stability and ultimately energy efficiency. 6 These losses are typically compensated for by AlF 3 addition to the cells, but this constitutes a materials input and cost to the smelter.…”

Section: Introductionmentioning

confidence: 99%

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The Pivotal Role of Alumina Pore Structure in HF Capture and Fluoride Return in Aluminum Reduction

McIntosh

Agbenyegah

Hyland

et al. 2016

JOM

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Fluoride emissions during primary aluminum production are mitigated by dry scrubbing on alumina which, as the metal feedstock, also returns fluoride to the pots. This ensures stable pot operation and maintains process efficiency but requires careful optimization of alumina for both fluoride capture and solubility. The Brunauer-Emmett-Teller (BET) surface area of 70-80 m 2 g À1 is currently accepted. However, this does not account for pore accessibility. We demonstrate using industry-sourced data that pores <3.5 nm are not correlated with fluoride return. Reconstructing alumina pore size distributions (PSDs) following hydrogen fluoride (HF) adsorption shows surface area is not lost by pore diameter shrinkage, but by blocking the internal porosity. However, this alone cannot explain this 3.5 nm threshold. We show this is a consequence of surface diffusion-based inhibition with surface chemistry probably playing an integral role. We advocate new surface area estimates for alumina which account for pore accessibility by explicitly ignoring <3.5 nm pores.

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Section: Resultsmentioning

confidence: 99%

Section: The Impact Of Alumina Pore Size On Fluoride Balances In An Omentioning

confidence: 99%