Properties of Waste Derived Mullite
Waste sediment (WS) from three different aluminum factories and rice husk ash (RHA) from power plants are used as precursors. Each WS is calcined to remove structural water then mixed and wet milled with RHA by 70 wt% until a homogeneous slip is obtained. The samples are formed by means of slip casting in plaster molds and fired at 1400 °C for 2 hours. The fired samples normally contain ~94 wt% mullite, 6 wt% residual silica and small amount of oxides of alkali and alkaline earth elements. It is found that their density and flexural strength are affected by alkali and alkaline earth contents and generally range from 1.53 to 2.38 g/cm3 and 18.11 to 76.37 MPa, respectively. While thermal expansion coefficient varies from 5.78 x 10-6 to 8.16 x 10-6 /°C and thermal shock resistance (T) from =200 to 300 °C.
Hyungsun Kim, Junichi Hojo and Soo Wohn Lee
U.S. Sanewirush et al., "Properties of Waste Derived Mullite", Materials Science Forum, Vols. 544-545, pp. 605-608, 2007