Characterization of red mud derived from a combined Bayer process and bauxite calcination method

Liu, Yong and Lin, Chuxia and Wu, Yonggui (2007) Characterization of red mud derived from a combined Bayer process and bauxite calcination method. Journal of Hazardous Materials, 146 (1-2). pp. 255-261. ISSN 0304-3894

Abstract

Red mud can be derived from the processing of bauxite using different methods. The chemical and mineralogical composition of the combined Bayer Process and bauxite calcination red mud (BPBCRM) differs markedly from those of the pure Bayer Process red mud (PBPRM). In this study, red mud derived from a combined Bayer Process and bauxite calcination method was characterized. The results show that pH of the red mud decreased with increasing duration of storage time. Na dominated among the soluble cations, but the concentration of soluble Na decreased with increasing duration of storage time as a result of leaching. Cation exchange capacity also decreased with increasing duration of storage time, probably due to a decrease in pH causing a reduction in negatively charged sites on the red mud particles. Ca was the predominant exchangeable cation in the fresh red mud but the concentration of exchangeable Ca markedly decreased in the old red mud, which was dominated by exchangeable Na. The degree of crystallization and thermal stability of the red mud increased with increasing duration of storage. The acid neutralizing capacity of red mud obtained from this study was about 10 mol kg−1, which is much greater than the reported values for the pure Bayer Process red mud. Column filtering experiment indicates that the red mud also had a very strong capacity to remove Cu, Zn and Cd from the filtering solution. It is conservatively estimated that the simultaneous removal rates of Cd, Zn and Cu by red mud are over 22,250 mg kg−1, 22,500 mg kg−1 and 25,000 mg kg−1, respectively. The affinity of these metals to the red mud was in the following decreasing order: Cu > Zn > Cd. In general, the fresh red mud retained more heavy metals than the old red mud did.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Depositing User: epEditor USQ
Faculty / Department / School: Current - USQ Other
Date Deposited: 25 May 2011 11:20
Last Modified: 03 Jul 2013 00:37
Uncontrolled Keywords: red mud; Bayer process; bauxite calcination; acid neutralizing capacity; calcite; caustic substance
Fields of Research (FOR2008): 09 Engineering > 0914 Resources Engineering and Extractive Metallurgy > 091404 Mineral Processing/Beneficiation
05 Environmental Sciences > 0503 Soil Sciences > 050304 Soil Chemistry (excl. Carbon Sequestration Science)
04 Earth Sciences > 0403 Geology > 040310 Sedimentology
Socio-Economic Objective (SEO2008): D Environment > 96 Environment > 9605 Ecosystem Assessment and Management > 960508 Ecosystem Assessment and Management of Mining Environments
Identification Number or DOI: doi: 10.1016/j.jhazmat.2006.12.015
URI: http://eprints.usq.edu.au/id/eprint/18891

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