Development of alkaline electrochemical characteristics demonstrates soil formation in bauxite residue undergoing natural rehabilitation

Kong, X., Tian, T., Xue, S., Hartley, W., Huang, L., Wu, C. and Li, C. (2017) Development of alkaline electrochemical characteristics demonstrates soil formation in bauxite residue undergoing natural rehabilitation. Land Degradation & Development.

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Mining and mineral processing industries have generated a large amount of polymineral wastes, causing the destruction and degradation of huge areas of landscapes at extensive geographical locations. Rehabilitation of these mine waste landscapes is critical to social and economic sustainability of mining and metallurgy operations, such as alumina refineries. The Bayer process to refine alumina generates large amounts of highly alkaline bauxite residues which are hazardous to plant growth. Innovative methodologies are urgently needed to address this economic and environmental challenge, one of which is soil formation from bauxite residues. Mineral weathering appears the prerequisite to the initiation of soil formation and development of functional soil properties in BRDAs. The present study investigated natural changes of mineralogy, zeta potential, isoelectric point, surface protonation, active alkaline groups and associated implications for rehabilitation of the BRDA. Alkaline calcite, hydrogarnet and sodalite minerals were slowly transformed or dissolved with declining levels over weathering time. Amorphous and semi-amorphous minerals also decreased with a corresponding decrease in BET and sorption sites. Zeta potential curve of fresh residue had steeper slope, than those of aged residues. The IEP of fresh residue was significantly higher, but those of aged residues were significantly lower, with a significant decrease of IEP with increasing time. These attributes in mineralogy and electrochemical characteristics such as transformation of alkaline minerals, and decreases of surface protonation and active alkaline groups, may be used to help the assessment of soil formation status in the bauxite residues of different age and associated rehabilitation requirements.

Item Type: Article
Keywords: Bauxite residue, alkalinity, land degradation, electrochemical characteristic, natural rehabilitation
Divisions: Crop and Environment Sciences (to 31.07.20)
Depositing User: Ms Kath Osborn
Date Deposited: 23 Nov 2017 19:06
Last Modified: 26 Oct 2018 04:10

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