Properties of sintered mullite and cordierite pressed bodies manufactured using Al-rich anodising sludge

Mullite and cordierite based refractory ceramic materials were produced from formulations based on an industrial Al-rich sludge derived from the wastewater treatment of the aluminium anodising process. Some common ceramic raw materials, like ball clay, kaolin, diatomite and talc, were also added. Cylindrical samples processed by uniaxial dry pressing were sintered at different temperatures (between 1300 and 1650 °C, 1 h soak at each temperature) to study the ceramic properties. The fired properties of materials was evaluated (firing shrinkage, water absorption, bending strength, thermal expansion coefficient, refractoriness and SEM microstructure) and demonstrated that optimal properties were obtained at 1650 °C for mullite and 1350 °C for cordierite.