Study on the Influence of Molding Methods and Binders on the Properties of Spinel Sintered Bricks from Secondary Aluminum Dross

Harmless treatment significantly raises the alumina content of secondary aluminum dross (SAD), laying the foundation for the preparation of MgAl2O4 (MA) refractory bricks from SAD by doping MgO. Relevant research on different molding methods, as well as the effects of binder types and dosages on the physical properties (such as compressive strength, thermal conductivity, and thermal shock resistance) of sintered bricks, remains inadequate. In this study, 15 wt% MgO was first added to make the Al2O3/MgO mass ratio of SAD close to the theoretical value of 2.53 for MA formation, and the SAD-MgO premix was used as raw material. The influence of molding methods and binders on the properties of sintered bricks was investigated. The results indicate that dry pressing outperforms casting in physical performance. When calcium lignosulfonate (CL) was used as the binder for dry pressing, the average compressive strength reached a maximum of 102.12 MPa, the corresponding thermal conductivity was 2.24 W/(m·K), and the sample withstood 11 thermal shock cycles. Binder dosage experiments showed that the optimal CL addition was 5 wt%, and the recommended upper limit was 10 wt%. This work provides a new perspective for the high-value utilization of SAD in the preparation of spinel refractory bricks.