Ceramic Properties of Alumina and Alumina-Mullite Pressed Bodies Based on Al-Rich Anodising Sludge

Abstract

Alumina and alumina-mullite 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. Other ceramic raw materials like diatomite was also added, which can be consider as a by-product. Cylindrical samples processed by uniaxial dry pressing were sintered at different temperatures (between 1400-1650°C, 1 hour soaking) to study the ceramic properties evolution. The performance of fired 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 alumina and 1450°C for alumina-mullite.

Impedance Spectroscopy Evolution upon Sintering of Alumina Bodies Containing Al-Rich Anodizing Sludge

“…In other hand, the recycling of an Al-rich anodising sludge as a major component of different ceramic compositions has been tested [8,9]. Full characterization and specification of pre-treatment needs of the Al-sludge, and its mixture with natural components, such as kaolin and clays has been studied and related before [8][9][10][11]. The main goal was to prove that this waste can be regarded as a useful raw material for other industries, such as ceramic, thus reducing the negative environmental impact associated with landfill and preserving non-renewable nature resources.…”

“…Normally the formation of liquid phase controls the sintering process of the common ceramic formulations. The relative amount and composition of such phase is crucial in determining the sintering kinetics and then all the related properties of the fired material, such as the densification, mechanical strength, etc [1,10,11]. Dilatometry is the common technique used to follow this process.…”