Technological Characterization and Industrial Application of Tunisian Clays from Makthar Area (Central Tunisia) in the Ceramic Industry

Abstract

This study focused on the geochemical, mineralogical and technological characterization of clays in Makthar area (Central of Tunisia) of Cretaceous-Paleogene. Its aims are to identify and promote use in the field of ceramics industry. The result of the mineralogical analysis of clays showed a dominance of illite with a percentage higher than 65%, of kaolinite and smectite with percentages of 15%. Geochemical analysis of the major elements of clay showed a SiO 2 content exceeding 29% and a percentage of Al 2 O 3 higher than 7.5%. The Fe 2 O 3 percentage was ranging from 3% to 8%. The percentage of CaO was between 22.5% and 28% while that of K 2 O is 4%. The percentages of SO 4 , MgO and NaO 2 were in very small fractions. Granulometric and microgranulometric analysis showed that the clay fraction (<2 μm) varies from 30% to 37%. The plasticity index showed the plasticity character of clays which presented a specific surface area ranging from 112 m 2 /g to 178 m 2 /g reflecting illite dominance. Drying behavior indicated that clay mixture had a drying shrinkage less than 7%, while the firing shrinkage didn’t exceed 2% giving the possibility of clay using in the ceramics field.