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Kinetic parameters of Al–Si spinel crystallization from Algerian tamazarte kaolin
Foudil Sahnoune, Djaida Redaoui and Messaoud Fatmi
In this study, the mechanism and kinetic parameters of Al–Si spinel crystallization from Algerian Tamazarte kaolinite was studied by Differential thermal analysis (DTA) technique, which were carried out on samples between room temperature and 1400°C at different heating rates (10–40°C/min). X-ray diffraction was used to identify the phases present in the samples. The activation energies measured by both isothermal (Johnson–Mehl–Avrami (JMA) theory using Ligero method) and non-isothermal (Kissinger methods) treatments are 870 and 810 kJ/mol, respectively. The growth morphology parameters n (Avrami parameter which indicates the crystallization mode) were found to be almost equal to 1.08, using non-isothermal treatments, and equal to 1.17 using isothermal (Ligero method) and m (the numerical factor which depends on the dimensionality of crystal growth) was 1.07 obtained by Matusita and al. equation. Analysis of the results showed that bulk nucleation was dominant in Al–Si spinel crystallization followed by two-dimensional growth of mullite crystals with plates morphology controlled by diffusion from a constant number of nuclei.
Keywords: Kaolin, Differential thermal analysis, Avrami parameter, Activation energy, Kinetic parameters, Al–Si spinel.