An evaluation of Palaeocene kaolin deposits in northeastern Nigeria

Three kaolin deposits in the Palaeocene Kerri-Kerri sandstone-dominated basin in northeastern Nigeria have been evaluated with respect to their particle size distribution (psd) and colour, and mineralogical and chemical compositions. The kaolin is fine-grained (≥ 80.75 wt % finer than 2 μm) and light grey to white. In terms of mineralogy, X-ray diffractograms show that the deposits are substantially rich in kaolinite and have subordinate amounts of quartz and illite whereas goethite, hematite and halloysite occur in trace amounts. CaO, Na₂O and MgO concentrations are low (≥0.44 wt %) indicating that kaolinitisation resulted from weathering accompanied by leaching of the alkalis. This process resulted in complementary enrichment of SiO₂ and Al₂O₃. Low Fe₂O₃ (≤ 1.20 wt %) as well as low MnO (≤0.03 wt %) makes the kaolin suitable for use in industrial applications in which colour in the end product is not desirable. With an estimated minimum reserve of 8.2 × 10¹⁰ tons, these deposits are economically viable pending further detailed investigations.