Valorization of Coniacian-middle Campanian clay minerals of the Meknassy-Mezzouna region (centerwestern Tunisia) in the clinker manufacturing

The present work is concerned with the valorization of clay minerals of the Aleg formation (Coniacian-middle Campanian) in the clinker manufacturing. The studied clays (17 samples) were collected from three lithological sections: Jebel Lhassem (LH), Jebel Er Rouijel (AR), and Oued El Hachene (OH). All these samples were characterized by XRD and x-ray fluorescence. The selected clays are essentially composed of smectites with variable percentages of kaolinite. The associated minerals are mainly calcite and quartz. The limestones necessary for the cement manufacturing are extracted from the Abiod formation due to their richness in CaO. Therefore, 70 mixtures of clays and limestones were realized. The study of the variation of the module alumino-ferric (AFM) according to the silicic module (SM) have revealed 5 mixtures being situated in a very favorable zone (TF), 54 mixtures being situated in a favorable zone and 11 mixtures averagely favorable to the manufacturing of the clinker. The correction of SM modules by the addition of 4 to 5% of sand for 54 mixtures is satisfactory and these modules are returned to the very favorable zone, while respecting the hydraulic module. The two clinkers (A and B) are selected according to the composition of their raw material. Although the raw material of the clinker (A) does not undergo any correction, the raw material of the clinker (B) is corrected by adding sand. The Bogue calculations, shown by the results of the x-ray diffraction of these two clinkers after heating at 1450 °C, has revealed high proportions of C3S, which are estimated by (71–77.53%), thus making less belite. While the ferrite (C4AF) is present in low quantities (4%), the free lime and the periclase (MgO) are present in trace amounts. This may indicate an effective clinkerization and a low expansion with water. The obtained clinker seems to have high resistance of the cement, a better grindability, and a low necessity in gypsum because the C3S percentage is more than 50%.