Mullite-Alumina Refractory Ceramics Obtained from Mixtures of Natural Common Materials and Recycled Al-Rich Anodizing Sludge

Abstract

This work describes attempts to reuse Al-rich sludge produced from industrial anodizing and surface treatment processes in the fabrication of mullite-based refractory materials. The complete characterization of the residue is reported, including physical and compositional parameters. Mixtures with common natural silica-containing materials, like ball clay, kaolin, and/or diatomite were prepared in order to achieve interesting final fired compositions. Rheological characterization of the suspensions, their slip casting performance, the thermal behavior of the consolidated bodies, and crystalline phase evolution are also detailed. From the knowledge acquired, pretreatment operations have been suggested to facilitate the recycling of the Al-rich sludge and to improve the characteristics of mullite-based materials.