Formulation of Bogue Equations from Thermodynamic Modelling for Low-Carbon Dioxide Ferrite-Belite Clinkers

In this study, limestone (LS), kaolin (K) and bauxite residue (BR) were considered as potential raw meal ingredients for the preparation of ferrite-belite (cement) clinkers. A forecast of the mineralogical composition for the different clinker composition, based on the major oxides, i.e., CaO (C), SiO₂ (S), Al₂O₃ (A) and Fe₂O₃ (F) was obtained using thermodynamic modelling (FactSage). A phase field schematic representation was established for the three-component raw meal. The data obtained therein were used to compute the Bogue equations for the ferrite-belite cements. Based on this assumption, i.e., only four simultaneous linear equations each containing four different variables (crystalline phases) were used to formulate Bogue type equations. It was established that with increasing LS content from 33 wt% to 64 wt% and BR content decreasing from 66 wt% to 35 wt%, CF was only present at an LS content between 33–47%, followed by gehlenite up to LS content of 53% and rankinite at a LS content of about 55 wt%. Moreover, C3A and lime were present in place of gehlenite and rankinite beyond LS content of 55 wt%. However, the belite and ferrite phases remained present throughout the entire clinker composition. Overall, this study provides the basic understanding required for the development of low carbon ferrite-belite clinkers.