Production of foundry filters using Al2O3 from Al-anodizing process

The manufacturing and materials transformation industries generate, to a greater or lesser extent, amounts of residues, which do not always have an adequate ecological destination. In many cases, however, these secondary products can be directly re-used as raw materials in other industrial processes. In this context, this article presents the characterization of the sludge generated in the aluminum anodizing process and emphasizes the application potential of this residue as a raw material for the production of industrial ceramic filters. Results show that the high alumina contents (89-97 wt%) and composition constancy, as well as the low particle size (~1 m) after calcination, render this residue a suitable raw material to produce alumina filters with optimized properties for filtration and so purification of liquid metals to cast engineering components with higher performance.