Characterization of the Dibang kyanite Minerals from the Southern Domain of the Central Fold Belt in Cameroon: Geological Environment, Liberation Mechanism and Industrial Properties
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The Central Africa Fold Belt (CAFB) in Cameroon, is made up of high-grade metamorphic rocks endowed with kyanite alluvial minerals that are poorly characterized for industrial purposes. To resolve this constraint, field occurrence, optical microscopic observations and morphoscopic study of Dibang kyanite alluvial minerals were carried out. X-Ray Diffraction, X-ray Fluorescence, thermal and sintering analyses were conducted to elucidate their geological environment, liberalization mechanism and industrial properties. In Dibang, kyanite minerals generally occur in kyanite-garnet micaschists, weathering mantles and in alluvial deposits. They are mostly elongated and prismatic with angular rounded or sub-rounded borders. They are of deep dark blue colour associated with garnet and quartz. Their quasi-smooth or smooth morphology is ascribed to the combined action of transportation (torrential and fluvial) and water erosion after withdrawal and release by residual drainage. Microscopic observations of fresh kyanite-garnet micaschists display a grano-nemato-lepidoblastic and oriented microstructure made up of garnet, quartz, kyanite, muscovite, plagioclase, pyroxene and opaques minerals. X-Ray Diffractogram portrays kyanite, with impurities, including micas, muscovite, K-feldspars, quartz, and pyrite mineral phases. The naturally composed mineral composition of the kyanite deposit is pseudo-perfect for the formation of mullitized elements, impeccable for refractory applications. X-ray fluorescence of major elements shows the predominance of alumina and silica, and a quite low percentage of iron oxide. The alkaline and the alkali earth metal oxides occur in traces. The thermal and sintering analysis demonstrates mutillization and recrystallization processes at quite low temperatures (1100ºC to 1300 ºC), with the complete transformation of kyanite to mullite.
