Prediction of solubilities of aluminium hydroxyfluoride hydrate recovered from spent pot lining

Ntuk, Ubong, White, Edward, Tait, Stephan and Steel, Karen (2013). Prediction of solubilities of aluminium hydroxyfluoride hydrate recovered from spent pot lining. In: Proceedings of Chemeca 2013: Challenging tomorrow. Chemeca 2013: Challenging tomorrow, Brisbane, QLD, Australia, (1-6). 29 September–2 October, 2013.

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Name Description MIMEType Size Downloads
Author Ntuk, Ubong
White, Edward
Tait, Stephan
Steel, Karen
Title of paper Prediction of solubilities of aluminium hydroxyfluoride hydrate recovered from spent pot lining
Conference name Chemeca 2013: Challenging tomorrow
Conference location Brisbane, QLD, Australia
Conference dates 29 September–2 October, 2013
Proceedings title Proceedings of Chemeca 2013: Challenging tomorrow
Place of Publication Barton, ACT, Australia
Publisher Institution of Engineers Australia
Publication Year 2013
Sub-type Fully published paper
Open Access Status
ISBN 9781922107077
Start page 1
End page 6
Total pages 6
Collection year 2014
Language eng
Formatted Abstract/Summary
Spent pot lining (SPL) is a hazardous waste containing fluoride, generated in the production of primary aluminium. About 7 to 30 kg of SPL is generated per tonne of primary aluminium. Over the years, much research has been carried out to offer an economic method of treatng this waste, but to date no such method is widely accepted. Chemical leaching and recovery of valuables have been found to be a promising option. A previous study has successfully recovered the fluoride values by crystallizing aluminium hydroxyfluoride hydrate (AHF). However the crystal size obtained was too small for potential industrial interest. This work is focused on means of producing larger crystals. A vital property for crystallization is solubility, and there have not been reliable solubility measures for AHF. Knowing the solubility product (Ksp), the solubility at various conditions may be predicted by a speciation program with an appropriate activity model. In this work, experimental measurements determined pKsp as 23.5 +/- 0.3 (95% probable error). Using this pKsp value in the speciation program PhreeqC, solubilities at various conditions were predicted. The solubility in water was found to be very low, but much higher in acid (with a negative effect of increasing temperature). The effect of an impurity on the solubility is also presented. The predicted phase diagrams suggest potentially viable crystallization pathways for further testing through follow-up experimental work.
Keyword Spent pot lining
Aluminium production
Chemical leaching
Speciation program
Crystallization
Aluminium hydroxyfluoride
Q-Index Code EX
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Presentation Type: Poster; Abstract Number: 25182.

Document type: Conference Paper
Collections: School of Chemical Engineering Publications
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Created: Mon, 31 Mar 2014, 13:48:43 EST by Dr Karen Steel on behalf of School of Chemical Engineering