Abstract

Clay occurrences at Okija, Ubiaja and Iyuku in southern Nigeria were characterized geochemically, mineralogically as well as geotechnically in order to evaluate their industrial potentials. Mineralogical analyses portray kaolinite as the dominant clay mineral with traces of illite in the transported Okija and Ubiaja samples.

Abundances of major elements show that SiO₂ (ca 50.41-64.45%) and Al₂O₃ (ca 18.62-31.62%) constitute over 80% of the bulk chemical compositions. Other constituents include Fe₂O₃, K₂O, T_iO₂, CaO, MgO and MnO. Although notable disparities exist in the S_iO₂ and Al₂O₃ contents of the clays, the Iyuku sample is more siliceous and less aluminous than the others.

Geotechnically, the in-situ derived Iyuku clay has distinctive characteristics. It is considerably less plastic, non-expansive, less hydrophilic and of low compressibility due to its lower clay fraction and higher crystallinity of available kaolinites. On the other hand, the Okija and Ubiaja clays are characterized by medium to high plasticity and compressibility. The shrinkage characteristics of the clays as well as their colloidal activities are consistent with their plasticity.

Evaluation of the industrial potential of the clays based on their physical, chemical and geotechnical characteristics revealed that they are suitable for the production of refractory bricks and ceramics. Appropriate processing/beneficiation would be mandatory if they are to qualify for other industrial applications, such as rubber, paper, paint and cosmetic industries.

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