Clinkerization of carbonatable belite-melilite clinker using solid waste at low temperature

A low calcium carbonatable belite-melilite clinker using around 70 wt% solid waste as raw material was designed in this work. Mechanisms of the phase transformation between belite, melilite and rankinite phase during clinkerization induced by MgO components were discussed combining phase diagram analysis and testing experiments such as quantitative XRD analysis and SEM. The clinker was prepared at around 1200 degrees C because of the components which facilitate the formation of melts such as MgO and Fe2O3. The clinkerization temperature, mechanical performance and CO2 fixation were discussed. The results show that much MgO component in the raw material causes the absence of C3S2 phase and the phase transformation of belite to C2MS2 phase because of the opposite driving force for the precipitation of the C3S2 phase from the liquid phase. In this work, the carbonatable belite-melilite clinker prepared from solid wastes shown narrow clinkerization temperature range, with the suitable clinkerization temperature at 1210 degrees C. Elevated clinkerization temperature facilitates the formation of C2MS2 phase by the reaction between the belite and the MgO component in the melts, leading to poor mechanical performance.