Evaluation of aluminum slag wastes in ceramic crucibles compositions and investigation of its effects on slurry rheology
摘要
This study aims to investigate the usability of corundum (Al₂O₃) phase obtained by calcination of aluminum slag as an alternative raw material instead of pure alumina oxide which is widely used in crucible production. This study explores the recycling of aluminum dross, which typically contains around 70% alumina and other oxides such as those of magnesium, calcium, titanium, potassium, and iron, for use in crucible production. To ensure the suitability of dross for this application, a purification process is performed to remove harmful compounds like aluminum nitride, fluorides, and chlorides. The dross is ground and calcined at 1400 °C. Its chemical and physical properties are then characterized using XRF and XRD. In the preparation of slurries for slip casting, alumina powder, kaolin, sodium silicate solution, and polysaccharide are combined with dross. Viscosity measurements and zeta potential analyses are conducted to evaluate the rheological behavior and stability of the slurries, helping to determine the optimal dross content for maintaining fluidity and efficient casting. Various samples with dross contents ranging from 10 to 50% by weight are prepared and fired at 1600 °C. The change between 10% and 50 wt% contribution rates was evaluated observationally in terms of technological properties rather than statistical analysis. The results suggest that incorporating 10% dross by weight showed the closest technological properties to the standard sample with a density of 3.60 g/cm3, a water absorption rate of 0.35% and a bending strength of 220.15MPa and doesn’t significantly impair the casting ability of the slurries. However, higher dross levels increase the viscosity, leading to more noticeable microstructural porosity. XRD and SEM analyses reveal the presence of corundum and quartz phases in the fired samples, with a higher proportion of aluminum-rich phases emerging as the dross content increases. Specifically, as the dross content increased from 10% to 50 wt%, the water absorption of the samples rose markedly from 0.18 to 3.95%, while the bulk density decreased from 3.69 g/cm3 to 2.75 g/cm3, which is attributed to increased porosity, while bulk density and bending strength decline. Overall, the study concludes that aluminum dross can serve as a partial substitute for alumina in the production of crucibles.
Graphical abstract