Settling behaviours of low alumina/caustic ratios during seawater neutralisation of Bayer liquor

Outram, John G., Couperthwaite, Sara J., Bouzaid, Jocelyne, & Millar, Graeme J. (2015) Settling behaviours of low alumina/caustic ratios during seawater neutralisation of Bayer liquor. In 10th International Alumina Quality Workshop, 19-24 April 2015, Perth, Western Australia.


Factors that affect the settleability of seawater neutralised bauxite refinery residues are poorly understood, in particular, the settleability of precipitates in the absence of red mud and those formed with different alumina/caustic (AC) ratios. The influence of temperature, AC ratio, caustic concentration and the volumetric ratio of seawater on the settleability of seawater neutralisation precipitates and their respective compositions and stabilities have been determined. An array of techniques have been used to determine the composition and stability of precipitates and include pH, conductivity, inductively coupled plasma optical emission spectroscopy, infrared spectroscopy and X-ray diffraction. Temperature has been shown to have a significant influence on the settleability and calcium carbonate phase distributions in precipitates, as well as the overall stability of the precipitates. More complex phase compositions have also been found for Bayer liquors with lower AC ratios. The caustic concentration and temperature of the reaction have the greatest influence on the settling efficiency of the precipitates. Assessments on the chemical stability of the precipitates, precipitate settleability and discharge water quality have been made. In addition, productivity and environmental impacts caused by changes in precipitate settleability have also been considered.

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ID Code: 87028
Item Type: Conference Paper
Refereed: Yes
Additional URLs:
Keywords: Bayer liquor, Settling, Seawater neutralization, Bauxite residue
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2015 [please consult the authors]
Deposited On: 31 Aug 2015 02:02
Last Modified: 27 Jan 2017 12:23

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