Value-added utilization of secondary aluminum dross in fabricating high-porosity and high-strength foam ceramics

Secondary aluminum dross (SAD) is a hazardous waste generated during aluminum production and recycling, which poses significant environmental risks when disposed of through conventional landfilling. However, it is rich in aluminum resources. To make rational use of the aluminum resources in SAD, this study presents a method for preparing foam ceramics by partially replacing commercial Al₂O₃ with SAD without the need for pretreatment, utilizing a particle-stabilized foaming method. The effects of SAD addition, solid content, and nano-sized Al₂O₃ addition on the porosity and compressive strength of the samples were investigated, and the synergistic regulatory mechanism of the raw material ratio on material properties was analyzed. The optimized conditions were found to be 24.35 wt% SAD addition, 21.81 wt% solid content, and 15.2 wt% nano-sized Al₂O₃, resulting in foam ceramics with porosity and compressive strength of 92.64 % and 2.28 MPa, respectively. SEM results revealed a multiscale pore structure with large pores (39.34 μm) and small pores (3.73 μm), effectively enhancing the compressive strength of the material. This study overcomes the negative correlation between porosity and compressive strength traditionally observed in foam ceramics, providing an engineering approach for the high-value utilization of SAD.