Abstract:Secondary aluminum dross (SAD) is a hazardous waste produced in aluminum industry casting process, which can be used to prepare valuable magnesium aluminate spinel refractory. However, the silicon easily transforms into low expansibility silicate minerals, which affects the quality of products. A new process for preparation magnesium aluminate spinel refractory using acidolysis residue from SAD was proposed, which consisted three steps, i.e., mild desilication, molding of desilication residue, and sample sintering. Effects of NaOH concentration, L/S, reaction temperature, and reaction time on removal rate of silicon impurity were systematic investigated in mild desilication process, and the kinetics calculation and transformation behavior analysis of desilication process were also carried out. The results show that removal rate of silication is 49.60% under the optimum conditions including NaOH concentration of 100 g/L, L/S of 6 mL/g, reaction temperature of 70 ℃, and reaction time of 10 min. Under the conditions of 20% of light magnesium oxide addition, forming pressure of 150 MPa, sintering temperature of 1 600 ℃, and sintering time of 3 h, the volume density and apparent porosity of prepared magnesium aluminate spinel is 2.76 g/cm3 and 21.85% respectively, which can meet the requirements of industrial use. This study can provide a new idea for resource utilization of SAD.