کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4731487 | 1640412 | 2012 | 10 صفحه PDF | دانلود رایگان |
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.
► Mineralogical characteristics in Quaternary bauxite ore are examined.
► Genesis and evolution of major minerals are presented.
► Ore-forming environments of Permian and Quaternary bauxite are discussed.
► Mineral changing during the formation of Quaternary bauxite is presented.
► Ore-forming process of Quaternary bauxite is updated.
Journal: Journal of Asian Earth Sciences - Volume 52, 30 June 2012, Pages 53–62