Sintering fabrication of magnesia-alumina spinel by secondary aluminum dross

Magnesia-alumina (MA) spinel by sintering secondary alumina ash from the secondary aluminum dross was studied. Thermodynamic analysis showed that MA material can be prepared theoretically by adding MgO to secondary aluminum ash. The results showed that MA spinel could be obtained under the sintering temperature from 1100 to 1500 ℃ when the mass ratio of aluminum dross to MgO was 1∶0.2, respectively. The purity and crystallinity of MA spinel improved significantly. In addition, the compressive strength increased, while apparent porosity decreased with the increasing of sintering temperature. When the sintering temperature was 1400 ℃, the apparent porosity and density of the prepared MA spinel were 9.65% and 2.02 g/cm³. The linear expansivity and the compressive strength were 38% and 89.8 MPa. The compressive strength of MA spinel reached the national standard of People's Republic of China for Magnesium brick and magnesium-aluminum brick (GB/T 2275-2007) (40 MPa), that is, the compressive strength was more than 40 MPa. The results showed that the MA spinel could be synthesis using the secondary aluminum dross with MgO. Therefore this technique provided the possibility of reutilization of the secondary aluminum dross in an environmentally friendly way.