Characterization of the Dibang kyanite minerals from the southern domain of the Central African Fold Belt in Cameroon for refractory applications

The Central African Fold Belt (CAFB) in Cameroon is made up of high-grade metamorphic rocks endowed with kyanite minerals that are poorly characterized for industrial purposes. To resolve this constraint, field occurrence, optical microscopic and morphoscopic study of the Dibang kyanite minerals, by X-Ray Diffraction, X-ray Fluorescence, thermal and sintering analyses elucidate that in Dibang, kyanite minerals occur in kyanite-garnet micaschists, weathering mantles and 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 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, mica, plagioclase, pyroxene and opaques minerals. X-Ray Diffractogram portrays kyanite, with impurities, including micas (biotite and 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, with Al2O3 / SiO2 mass ratio of < 1.5% and a quite low percentage of iron oxide (Fe2O3 < 1%). The alkaline and the alkali earth metal oxides occur in traces. The thermal and sintering analysis demonstrates a relatively low mutillization temperatures of less than 1300 °C, portraying a considerably advantage in energy gain for potential industrial transformation into refractory elements.