Statistical research on phase formation and modification of alite polymorphs in cement clinker with SO3 and MgO

The design of experiments (DoE) was adjusted in cement clinker chemistry, with alite polymorphisms in the clinker taken into account. The additions of SO3, MgO, as well as two other factors, sintering temperature and time, were included to study clinker formation and alite polymorphisms. XRD quantitative analyses and thermal analysis (DSC–TG) were used to collect quantitative data from the samples and to investigate the clinkerization of the raw meal. The central composition design was used to design the experiments and the response surface methodology was used to evaluate the results. The addition of SO3 inhibited the formation of alite in the clinker, while MgO compensated for any negative effects caused by the SO3. A contour plot interpreted the combination effects of these four factors. The amount of C4AF was then increased with a likewise increasing SO3 content. MgO favored the formation of M3 type alites, while SO3 stabilized the M1. Alite modification, which is related to hydration properties, could be helpful for efficient use of high MgO content calcite in cement production.

► Design of experiments (DoE) was adjusted in the cement clinker chemistry. ► Combination effects come from the interactions of SO3 with MgO and temperature, which can demonstrate in the contour plot. ► MgO favors the formation of M3 type alite while SO3 stabilizes M1. ► Temperature and sintering time have little effect on the crystal modifications of alite. ► The amount of C4AF is increased with likewise increasing SO3 content.