Physico-chemical properties and industrial potential of some clay deposits in Calabar area, south eastern Nigeria

Abstract

Clay samples collected from 10 locations in Calabar, Cross River State, Nigeria were evaluated to determine their suitability for industrial applications. The samples were pulverized, dried, sieved and quantitatively analyzed. Physical properties determined were viscosity (11-15 secs), density (1072-1769 kg m-3), plasticity index (33-50%), particle size and firing characteristics. The clays were classified as fat clays or elastic silt. Results showed that all the clay samples were uniformly graded with fine texture and have the ideal silica value averaging 47.73% but the alumina content of the samples are lower than theoretical values of pure montmorillonite (28.3%) and kaolinite (39.5%), with averaging 18.0%. X-ray analysis indicated that the dominant clay mineral found in all the samples is kaolin with occasional illite and the main non-clay mineral as quartz. Considerable amounts of Fe2O3 (2.79-6.95%) along with
some impurity oxides such as MgO (0.08-0.98%), CaO (0.12-0.95%), K2O (0.28-1.82%), Na2O (1.02- 1.87%) and TiO2 (0.96-1.20%) were found in all the clay minerals. These properties indicated that the clays are of low grade (non- refractory) due to the low alumina content. The low alumina content with the relatively high plasticity index and the pleasant color characteristics of the clays on firing, suggest that the clays have the potentials for use in the production of brick, ceramic and pottery products.