Effects of Multiple Factors on the Compressive Strength of Porous Ceramsite Prepared from Secondary Aluminum Dross

Aluminum is one of the most in-demand nonferrous metals in the world. The secondary aluminum dross (SAD) produced during aluminum smelting is a type of solid waste that urgently requires disposal. SAD, municipal solid waste incineration fly ash, and bottom slag were used as raw materials to prepare porous ceramsite in a laboratory in this study. Multi-factor design experiments were then used to explore the influence of the sintering condition on the compressive strength to provide a basis for ceramsite preparation using SAD. The results showed that, within a certain variation range, the levels of each factor showed overall positive correlations with the ceramsite compressive strength. The contributions of the ceramsite particle size, the silicon-aluminum ratio (Si/Al), the sintering temperature, and the sintering time to the compressive strength of the porous ceramsite then decreased. The factors had a synergistic effect. The interactive effect of multiple factors on the porous ceramsite compressive strength rose with an increase in the particle size and Si/Al ratio. The average compressive strength of the porous ceramsite prepared in this study was 4.06 ± 3.71 MPa, and the maximum compressive strength was 14.13 MPa. The highest ceramsite compressive strength was achieved under a sintering temperature of 1270 °C, a particle size of 2 cm, a sintering time of 30 min, and a silicon-aluminum ratio of 1.5. In addition, there was a reaction relationship between the multiple factors involved in the sintering of the SAD-based porous ceramsite. Pilot or industrial tests should be conducted in the future based on these experiments and the intended ceramsite use.