Study on sintering behavior and properties of lithium slag-based foamed ceramics

To research the value of lithium slag in the development of construction materials, foamed ceramics with different lithium slag/kaolin have been prepared using the conventional high-temperature foaming method. In this study, the effects of sintering temperature and formulation on the morphology and mechanical properties of foamed ceramics are investigated by relying on the formula scheme designed by the Na2O-Al2O3-SiO2 ternary phase diagram. The characterization of the ceramic raw materials and samples by XRF, XRD, SEM, and TGA-DSC reveals that the doping contents of lithium slag have a great influence on the densification of the sample. With the amount of lithium slag increases, the amount of liquid phase in the melt increases, which intensifies the liquid phase flow and accelerates the mass transfer process, promoting the sintering and densification of ceramics. However, too much lithium slag is easy to agglomerate, which is not conducive to the close bonding between the internal components of the ceramic, resulting in a decrease in bulk density. In addition, the doping of spodumene effectively reduces the sintering temperature of the mullite matrix, promotes the formation of mullite crystals, and enhances the mechanical properties of the ceramics. The lithium-slag ceramics sintered at high temperature in this experiment had a maximum compressive strength = 5.70 MPa. average porosity = 73.68%, average apparent density = 0.40 g/cm3 and average water absorption = 2.24%. Overall, the lithium slag foamed ceramics prepared by the high-temperature foaming method have good mechanical properties, which are essential for resource utilization and high value-added utilization of solid waste.