Taguchi optimization to determine the influential beneficiation parameters of kaolin-clay materials for thermal applications

Beneficiation is utilized to minimize impurities and enhance the quality characteristics of kaolin-clay materials. Kaolin, a naturally occurring clay mineral, exhibits low thermal conductivity, which makes it an effective insulator that reduces heat transfer and improves energy efficiency in various applications. However, there is a scarcity of information regarding the effect of beneficiation time on the properties of kaolin clay materials. A wet beneficiation process was employed, in which samples were immersed in water within a plastic container and left to soak for 24 h. This process was repeated at 24-hour intervals up to 192 h, yielding ten beneficiated samples for characterization. Furthermore, experimental investigations were analyzed using the Taguchi optimization method, with a corresponding Taguchi L16 orthogonal array design comprising three factors: Time (hrs) – ranging from 0, 24, 48, 72, 96, 120, 144, 168, and 192 hrs; Temperature (TP) – at 28 and 400 °C; and Particle Size (PS) – at 25 and 75 µm – to determine the optimal alumina content in the kaolin-based ceramic material. Subsequently, thermogravimetric analysis was performed on the optimal samples. Taguchi optimization revealed that a beneficiation time of 96 h was the most significant factor in achieving the optimum alumina content, followed by temperature and particle size. A wet beneficiation reaction time of 96 h reduced iron oxide impurities from 12.55% to 4.10%. Simultaneously, aluminum oxide content increased from 22.22% to 38.55%, which represented the maximum value obtained among all samples. A clearer and more compact particle shape was also observed in the final Scanning Electron Microscope (SEM) evaluation of the sample beneficiated for 96 h, compared with the unbeneficiated kaolin. This study demonstrates that kaolin clay material from Ijero, Ekiti State, Nigeria, can attain its optimum properties through 96 h of beneficiation. The higher aluminum oxide content contributes to improved refractoriness and thermo-mechanical properties of the kaolin.