Utilization of some Egyptian Raw Materials in Ceramic Tiles

A ceramic tile batch from Egyptian raw materials includes kaolin, quartz and feldspar in addition to few additive of bentonite is designed. The phase and chemical composition of the raw materials are investigated using XRD and XRF, respectively. Kaolin is composed of kaolinite and quartz, while kaolinitic sand is formed essentially of quartz with a lesser content of kaolin. Feldspars are represented by albite and orthoclase with subordinate amounts of quartz. The batch was ground, mixed, shaped, pressed and fired from 1160 to 1260 °C. Linear shrinkage and bulk density were determined at dry state and after firing, while water absorption and porosity were detected after firing. The phase composition and microstructure as well as microchemistry of the batch fired at 1260 °C were detected using XRD and EDAX, respectively. Whiteness of the fired batches at 1260 °C is relatively low (49.85%), which is due the impurity contents in the used raw materials. It is concluded that by increasing the firing temperature, the bulk density and linear shrinkage increased, while apparent porosity and water adsorption decreased. The essential minerals of the fired batches at 1260 °C are quartz and mullite with few amounts of albite. The Microstructure and EDAX ensure the presence of primary mullite in a glass matrix.