期刊
JOURNAL OF ASIAN EARTH SCIENCES
卷 52, 期 -, 页码 53-62出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jseaes.2012.02.011
关键词
Karstic bauxite; XRD; SEM/EDS; DTA; EPMA; Ore-forming environment
资金
- Resource Exploration Bureau in Guangxi Province
- National Basic Research Program [2009CB421008]
- Program for New Century Excellent Talents [NCET -10-0752]
- National Natural Science Foundation [41102048]
In recent decades, more than 0.5 billion tons of ores scattered in the Quaternary laterite in western Guangxi, China have been explored. The ores were derived from a bauxite horizon in Permian via physical break-up and re-sediment process. Utilizing various test methods, i.e., XRD, DTA, TG/DTG, SEM/EDS and EPMA, the mineralogical characteristics of the Quaternary bauxite ores in jingxi and Debao counties were investigated. XRD was used together with TG/DTG to obtain relatively accurate ore mineral abundance. Diaspore is the major phase, whereas hematite, kaolinite, anatase, chamosite, gibbsite, goethite, illite and rutile are minor. Diaspore is characterized by a small particle size, low degrees of crystallinity and complex chemical composition. Both gibbsite and goethite have a varied particle size, and goethite crystals contain high Al substitution and Si. It is clarified that diaspore, chamosite and anatase were formed in a mildly reduced and alkaline depositional environment in Permian, while gibbsite, hematite, goethite and part kaolinite were precipitated from Al3+-, Si4+- and Fe3+-enriched solutions within an Quaternary oxidized environment. The ions Al3+, Si4+ and Fe3+ are mostly released from chamosite in its dissolution process. The different physicochemical conditions between the Permian depositional and the Quaternary weathering periods resulted in a complex mineral assemblage in the Quaternary bauxite. (C) 2012 Elsevier Ltd. All rights reserved.
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