Effect of O2/CO2 atmosphere on the mineral phase composition of cement clinker

Oxygen-enriched Combustion-flue Gas Recirculation (OEC-FGR) Technology is one of the main ways to solve the problem of CO2 emission during the cement production, which can greatly decrease CO2 capturing cost while realize CO2 enrichment. However, there is a lack of in-depth study of atmosphere change on the performance of cement clinker. An atmospheric furnace utilized in the paper to calcinate cement clinker and pure mineral [2CaO center dot SiO2 (C2S), No.33-0302, P21/n (14), 3CaO center dot SiO2 (C3S), No.49-0442, Cm (8)] under air and O2/CO2 atmosphere, and the influence of atmosphere on the structure, composition and performance of cement clinker and pure mineral by the means of X-ray diffractometer, Transmission Electron Microscope and other testing methods were studied. And then, the mechanism of atmosphere influence on the performance of cement clinker was revealed through simulation calculations and a Ca-SiO2 diffusion model was constructed. The results showed that the diffusion coefficients of Ca in hexagonal system and tetragonal system SiO2 are 1.53 x 10-8 m2/s and 1.26 x 10-8 m2/s, respectively. The O2/CO2 atmosphere is conducive to the generation of hexagonal system SiO2, thereby speeding up the generation of 3CaO center dot SiO2, which contributes to the improvement of cement clinker strength, so the appropriate proportion of O2/CO2 atmosphere is conducive to the improvement of cement clinker performance; the best O2/CO2 ratio in the study is 0.31/0.69. Performance testing, structural analysis, and simulation calculations were used in the paper to reveal the mechanism of the influence of atmosphere on cement clinker, providing a theoretical basis for the cement industry to achieve carbon emission reduction.