Journal ArticleDOI
Proposal for management and alkalinity transformation of bauxite residue in China
TLDR
Future research should focus on transformation chemistry and its associated mechanisms and for the development of a clear and economic process to reduce alkalinity and soda in bauxite residue.Abstract:
Bauxite residue is a hazardous solid waste produced during the production of alumina. Its high alkalinity is a potential threat to the environment which may disrupt the surrounding ecological balance of its disposal areas. China is one of the major global producers of alumina and bauxite residue, but differences in alkalinity and associated chemistry exist between residues from China and those from other countries. A detailed understanding of the chemistry of bauxite residue remains the key to improving its management, both in terms of minimizing environmental impacts and reducing its alkaline properties. The nature of bauxite residue and the chemistry required for its transformation are still poorly understood. This review focuses on various transformation processes generated from the Bayer process, sintering process, and combined Bayer-sintering process in China. Problems associated with transformation mechanisms, technical methods, and relative merits of these technologies are reviewed, while current knowledge gaps and research priorities are recommended. Future research should focus on transformation chemistry and its associated mechanisms and for the development of a clear and economic process to reduce alkalinity and soda in bauxite residue.read more
Citations
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Journal ArticleDOI
Acid transformation of bauxite residue: Conversion of its alkaline characteristics.
Kong Xiangfeng,Meng Li,Shengguo Xue,William Hartley,Chengrong Chen,Chuan Wu,Xiaofei Li,Yi-wei Li +7 more
TL;DR: SEM images suggest that mineral acid transformations promote macro-aggregate formation, and the positive promotion of citric acid, confirming the removal or reduction in soluble and exchangeable Na.
Journal ArticleDOI
Natural evolution of alkaline characteristics in bauxite residue
TL;DR: In this paper, the acid neutralizing capacity of bauxite residue was investigated by incubation with hydrochloric acid and batch neutralization experiments, which revealed a characteristic buffering behavior that could be controlled by its alkaline components.
Journal ArticleDOI
Evaluation of aggregate microstructures following natural regeneration in bauxite residue as characterized by synchrotron-based X-ray micro-computed tomography.
TL;DR: Under natural soil-forming processes bauxite residue porosity, specific surface area, average length of paths, and average tortuosity of paths all significantly increased, demonstrated that natural regeneration may stimulate the formation of stable aggregate structure in residues.
Journal ArticleDOI
Vermicompost and Gypsum Amendments Improve Aggregate Formation in Bauxite Residue
TL;DR: In this article, the effects of gypsum and vermicompost on related chemical and physical conditions of bauxite residue were studied in a laboratory incubation experiment, and the results suggest that application of the two materials may directly influence aggregate size distribution and its morphology.
Journal ArticleDOI
Phosphogypsum stabilization of bauxite residue: Conversion of its alkaline characteristics.
TL;DR: This research provided a feasible method to promote soil formation of bauxite residue by phosphogypsum amendment and could significantly promote the transformation of alkalinity cations by neutralization, precipitation and replacement reactions.
References
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Bauxite residue issues: II. options for residue utilization
TL;DR: In this article, a review of public domain information on bauxite residue re-use is presented, with a focus on the few highest volume uses of lowest risk, where the authors examine the reasons for inaction on residue use: volume, performance, cost and risk with the last two probably being paramount.
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Phytoremediation of mine tailings in temperate and arid environments
Monica O. Mendez,Raina M. Maier +1 more
TL;DR: There are two approaches to phytoremediation of mine tailings, phytoextraction and phytostabilization as discussed by the authors, both of which focus on establishing a vegetative cap that does not shoot accumulate metals but rather immobilizes metals within the tailings.
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Mechanism of Friedel's salt formation in cements rich in tri-calcium aluminate
TL;DR: In this article, the pore solutions from mortars containing NaCl and CaCl 2 added during mixing were analyzed, and it was shown that in the presence of NaCl the Friedel's salt forms by two separate mechanisms; an adsorption mechanism, and an anion exchange mechanism.
Journal ArticleDOI
Leaching of rare earths from bauxite residue (red mud)
TL;DR: In this paper, the authors performed leaching experiments on Greek bauxite residue with different acids at different concentrations, liquid-to-solid ratios, leaching times and temperatures.
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Hidden values in bauxite residue (red mud): recovery of metals
Yanju Liu,Ravi Naidu +1 more
TL;DR: A critical overview of the current techniques employed for iron recovery from red mud is presented to provide an insight into the full potential usage of red mud as an economic resource rather than a waste.