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Journal of Thermal Analysis and Calorimetry

, Volume 100, Issue 1, pp 27–32 | Cite as

Thermal decomposition of Bayer precipitates formed at varying temperatures

  • Sara J. Palmer
  • Ray L. Frost
Article

Abstract

Bayer hydrotalcites prepared using the seawater neutralisation (SWN) process of Bayer liquors are characterised using X-ray diffraction and thermal analysis techniques. The Bayer hydrotalcites are synthesised at four different temperatures (0, 25, 55, and 75 °C) to determine the effect of synthesis temperature on the thermal stability of the Bayer hydrotalcite structures and the mineralogical phases that form. The interlayer distance increased with increasing synthesis temperature, up to 55 °C, and then decreased by 0.14 Å for Bayer hydrotalcites prepared at 75 °C. The three mineralogical phases identified in this investigation are; (1) Bayer hydrotalcite, (2), calcium carbonate species, and (3) hydromagnesite. The DTG curve can be separated into four decomposition steps; (1) the removal of adsorbed water and free interlayer water in hydrotalcite (30–230 °C), (2) the dehydroxylation of hydrotalcite and the decarbonation of hydrotalcite (250–400 °C), (3) the decarbonation of hydromagnesite (400–550 °C), and (4) the decarbonation of aragonite (550–650 °C).

Keywords

Thermal analysis Hydrotalcite Bayer liquor Seawater neutralisation 

Notes

Acknowledgements

The financial and infra-structure support of the Queensland Research and Development Centre (QRDC-RioTintoAlcan) and the Queensland University of Technology Inorganic Materials Research Program of the School of Physical and Chemical Sciences are gratefully acknowledged.

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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2009

Authors and Affiliations

  1. 1.Inorganic Materials Research Program, School of Physical and Chemical SciencesQueensland University of TechnologyBrisbaneAustralia

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