Recycling of industrial waste iron tailings in porous bricks with low thermal conductivity

To meet the requirement of thermal insulation material in buildings, porous bricks with high porosity, high strength and low thermal conductivity were fabricated by foam-gelcasting technology using industrial waste iron tailings as raw materials. The effects of preparation parameter on phase composition, microstructure and mechanical strength of synthesised bricks were investigated in reference to Gibson model. The results showed that sintering temperature, soaking time and milling time had significant effects on porosity, compressive strength and microstructure of the porous tailing ceramics. Extending soaking time, meanwhile decreasing sintering temperature could effectively improve the compress strength of sample with similar porosity. The thermal conductivity of the porous tailing bricks could reach the lowest value of 0.032 W/(m.K) with the porosity of 89%. The thermal conductivity of samples with varied porosity is comparable with the calculated values deduced from the universal model, which make a good description of the relationship between porosity and thermal conductivity. It is a new way to recycle industrial waste into porous tailing brick which can be used as a building insulation material or filter material. (C) 2019 Elsevier Ltd. All rights reserved.