Simulation of flash dehydroxylation of clay particle using gPROMS: A move towards green concrete

The use of SCMs (supplementary cementitious materials) to replace part of the clinker in cement industry is gaining an increasing interest in order to reduce the CO2 footprint. The abundantly available clay minerals are potential sources of SCMs. Thermal treatment of kaolinite clay under moderate temperatures (700-1000K) yields an amorphous phase called metakaolinite, a material that has great promise as a mineral admixture for cement and concrete. However, the optimum properties of metakaolinite are highly dependent on operating temperature and residence time during thermal treatment. This article presents the development of a numerical model for the simulation of dehydroxylation of kaolinite clay using gPROMS (general PROcess Modeling System). Accordingly, a 1D dehydroxylation model is used to examine the thermal transformation of kaolinite into different phases. This model is used to predict the temperature and residence time at which the kaolinite particle attains optimum pozzolanic reactivity. The usefulness and validity of the method is evaluated by comparing the predicted variables with experimental values collected from a gas suspension calciner (GSC).