Preparation of Porous Ceramics with Red Mud and High-Aluminum Fly Ash by Melting Foaming Method

Porous ceramics were prepared by a high-temperature melting foaming method with red mud and high-aluminum fly ash as main raw materials. The effects of raw material composition and foaming process on the cellular structure and properties were investigated. The results show that the cellular structure of porous ceramic obtained after melt foaming at 1200 ℃ for 1 h changes from closed to open, eventually forming a composite cellular structure. Also, the average pore size and porosity increase, while the bulk density and thermal conductivity decrease with increasing the mass ratio of SiO₂/Al₂O₃ from 1.2 to 1.9 in the raw material composition. At the blowing agent of 5% (in mass fraction) SiC and the melting agent of albite and microcline of 35%, a composite cellular structure porous ceramic with the bulk density of 0.63 g/cm³, average pore size of 0.98 mm and bulk porosity of 70% is obtained, and its flexural strength and thermal conductivity are 7.17 MPa and 0.34 W/(m·K), respectively.