Reduction of clinkerisation temperature by addition of salts containing fluorine

Abstract

The influence of some salts containing fluorine (CaF2, NaF, and KF) on the reduction of burning temperature of Portland clinker from three Algerian cement factories (units of Zahana, Beni-Saf, Chlef) has been studied in this paper. X-Ray fluorescence, optical microscope technique, and powder X-ray diffraction were then used to characterize each clinker and its raw mixture in terms of chemical composition and clinker mineralogical composition. The effects of these mineralizers on structural and morphological properties of clinker minerals and on the presence of alite were investigated by scanning electron microscopy combined with microprobe analysis. Physical and mechanical properties (density, specific area, setting time, hydration heat, expansion, and mechanical strength) of some samples were studied. The results show that the presence of the mineralizers under study induced a decrease of the burning temperature. For example, NaF improved the crystallization of clinker minerals with high alite rate. These characteristics explain the improvement of physical and strength properties of the new clinkers.Key words: clinker, alite, structure, hydraulic activity, clinkerisation temperature, mineralizer.