Thermal and x-ray investigations of kowak clay in northwestern Tanzania and its possible industrial use
A study of some properties of clays collected from selected sites in Kowak deposit in Tarime District was carried out in order to assess their suitability as raw materials in ceramic and its related industries. The silica (SiO2) content in the clays is predominant, and is about 66.89% followed by alumina (Al2O3) that is 20.2%. Haematite (Fe2O3) was found to be the third in abundance with an average of 3.58%. Other constituents are present in small proportions. Water loss at 105 oC lies between 2.70% and 2.76%. DTG, TG, XRD techniques and chemical analyses studied by AAS method were used to determine the minerals present in the deposit. Two clay minerals, namely, illite and kaolinite were dominant. The non-clay minerals, referred to as “impurities” found in clays include quartz, pyrope and potash-feldspar (K2O.Al2O3.6SiO2) in the form of microcline. Illite, kaolinite, quartz and potash-feldspar were found in all sites of the deposit while pyrope was revealed in one site only. On the basis of this study, the results obtained from the chemical, thermal and mineralogical analyses, suggest that the clays from the deposit could be exploited for the manufacture of bricks, tiles and some limited ceramic ware.
Tanzania Journal of Science Vol. 32 (2) 2006: pp. 81-90