Abstract
Thermal activation of bauxite has been proposed to enable removal of organic carbon and reducing boehmite digestion temperature. However, there is limited published research about how thermally activated bauxite behaves at pre-desilication (<100 °C) conditions. Combining x-ray diffraction and scanning electron microscopy energy dispersive spectroscopy analysis of cross-sectioned samples, key differences in the desilication of bauxite and thermally activated bauxite are identified. The results show that the silicate dissolution rate of activated bauxite is fast and desilicated products do not appear within the first half an hour. At the same time and temperature, the leaching rate of aluminium bearing phases is inhibited by thermal activation . The subsequent filtration rate for activated bauxite residue is significantly shorter than for bauxite residue . Energy dispersive elemental mapping indicated thermal activation enables the dis-association of kaolinite phases from hematite and inert alumina phases.
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Acknowledgements
The authors gratefully acknowledge the financial support from the Advance Queensland Research Fellowship supported by Rio Tinto and Queensland Government (Grant ID 2015003035). We acknowledge the facilities, and the scientific and technical assistance, of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy and Microanalysis, The University of Queensland. We thank Warren Staker of Rio Tinto for his technical advice.
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Peng, H., Peters, S., Vaughan, J. (2019). Leaching Kinetics of Thermally-Activated, High Silica Bauxite. In: Chesonis, C. (eds) Light Metals 2019. The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-030-05864-7_2
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DOI: https://doi.org/10.1007/978-3-030-05864-7_2
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