Preparation of porous ceramics with waste zeolites as raw material

Nepheline porous ceramics with improved strength and well thermal insulation performance were synthesised at 850–1000°C by a foam-gelcasting technology, using waste zeolite powders, triethanolamine lauryl sulphate and xanthan gum respectively as the starting materials, foaming agent and gelling agent. The effect of sintering temperatures and solid contents on the physical and thermal properties of final samples were investigated. The strengths of foams increased with the firing temperatures and solid levels, and the sample possessing the porosity of 71.9% exhibited the highest compressive strength of 2.9 MPa 1, respectively. Moreover, the one with a solid content of 20 wt-% and fired at 950°C containing 76.9% porosity and having compressive strengths respectively of 1.8 MPa showed the lowest thermal conductivity of 0.10 W/(m oC) at 25°C, suggesting that as-prepared porous ceramics could be potentially used as a good thermal insulation material.