The Influence of SO3 and MgO on Kinetics of Alite Formation

This paper deals with monitoring of influence of minor oxides SO3 and MgO on the rate of alite formation in the Portland cement clinker in laboratory conditions. The study was carried out mainly by methods of optical microscopy. A special and unique laboratory equipment was used – a kiln with a manipulator and kinetic models already published were used for processing of the data. It was observed that increased content of these oxides can significantly influence the rate of alite formation. The formation rate was expressed by a change in a conversion degree of the alite formation in time. It was found that when the content of SO3 increases in a raw meal with ordinary content of alkalis, the initiation of the alite formation is delayed and the rate of its formation increases. The negative effect of SO3 on the initiation of the alite formation in such system can be compensated by increasing the MgO content, while the positive impact of SO3 on the growth rate of alite is kept unchanged. The paper also discusses formation of alite in clinkers with high content of SO3.