Effect of Fe₂O₃ content on clinkerization of low calcium carbonatable belite-rankinite clinker

Developing carbonatable clinker is an important method to reduce carbon emissions in the cement industry. Belite-rankinite based clinker is an attractive clinker due to its low calcium content, low clinkerization temperature, self-pulverization properties, and inherent CO₂ absorption capabilities. Effects of Fe₂O₃ content on clinkerization of low calcium carbonatable belite-rankinite clinker was studied in this work. Addition of Fe₂O₃ is beneficial for the clinkerization of belite-rankinite clinker, which can reduce the clinkerization temperature and promote the generation of melts at high-temperature, facilitating the reaction between solid C₂S and liquid SiO₂ to form C₃S₂. The optimum Fe₂O₃ content of 2–3 wt% was observed, which minimizes the content of f-CaO in the clinker. Quenching of the clinkers obtains lower f-CaO content than that in the slow cooled clinker. Viscous melts formed at high temperature causes the local reducing atmosphere and transition of Fe³⁺ to Fe²⁺. Fe²⁺ ions in the melts substitute Ca²⁺ ions when the rankinite precipitates from the melts during the cooling, causing an increase of f-CaO in the clinkers. The results were expected to provide theoretical guidance for the design and performance optimizing of carbonatable belite-rankinite clinker, contributing to energy and CO₂ emission reductions in the cement industry coupled with global sustainable development goals.