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Thermal Treatment of Kaolinite: Effects of Calcination Method on Chemical and Mineralogical Properties



Author(s)

Boris Ganmavo¹, Valéry Kouandété Doko¹, Edem Chabi², Arsène Bienvenue Soglo¹, Thède Agbelele¹ and Mohamed Gibigaye¹

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DOI:10.17265/2161-6213/2025.4-6.001

1. Laboratoire d'Energétique et de Mécanique Appliquée (LEMA), Polytechnic school of Abomey-Calavi, University of Abomey-Calavi, Abomey-Calavi 01 BP 526, Republic of Benin
2. Laboratory of Rural Engineering, School of Rural Engineering, National University of Agriculture, Ketou 01 BP 43, Republic of Benin

The aim of this research work is to analyze the possibility of heat-treating kaolinite clays under economic production conditions. It presents the results of heat treatment of kaolinite clays from Adjozoumè in the Kétou region of the Republic of Benin. Three heat treatment methods were analyzed. The first consisted in calcining the clay in a ceramic enclosure placed on a charcoal hearth, where the temperature was controlled and limited to 600 °C for 3 h. The second technique consists of calcining the clay in a laboratory kiln. The temperature is set at a rate of 10 °C per minute up to 700 °C. Once this temperature has been reached, it is maintained for 1 h. Finally, the last technique involves re-treating the clay from technique 1 in the laboratory oven at 700 °C for 1 h. Each of the samples resulting from these three techniques underwent XRD (X-ray diffraction) testing at an angle of 2θ. Both chemical and mineralogical compositions were analyzed. The results showed that all three samples had a major oxide content higher than that required by ASTM C618 (92.5%, 94.5% and 96% respectively). However, the clay processed in the furnace had a residual kaolinite content of 10%, suggesting incomplete calcination. Technique 3 seems to be the best, since it ensures complete dehydroylation of the kaolinite and has the best metakaolinite content. The first technique remains valid for the production of metakaolinite for pozzolanic use, but its performance is not as good. 

Clay, metakaolinite, heat-treating, pozzolanic, Benin, Ketou.