Characterization of a Water Clearing Treatment Residue and Its Application as Clay Ceramic Addition

Abstract

The addition of industrial residues into common red clay ceramic has been, from many decades, an alternative of using other low cost raw materials and, more recently, as an environmentally correct destination for polluting substances. An important residue, known as yellow sludge, is that generated at the water clearing stage (WCS) of a treatment plant by some heavy industries such as an integrated steel making. Since this yellow sludge residue is normally disposed in ways that pollutes water bodies, the objective of the present work was to characterize a WCS yellow sludge and investigate its addition into clay ceramics. The residue was characterized by X-ray fluorescence, particle size distribution and scanning electron microscopy. The addition was carried out up to 7.5 wt% followed by firing at 800oC. The added ceramics were evaluated in terms of water absorption, linear shrinkage, dry apparent density and flexural rupture strength. It was found that the residue addition does not practically alter the ceramic technical properties.