Sustainable Utilization of Lignite Bottom Ash (LBA) and Bituminous Bottom Ash (BBA) for Ceramic Foam Production

In this study, different sources of coal bottom ashes, industrial solid wastes/byproducts, generated from two coal-fired power plants, were utilized as raw materials in the ceramic industry due to their high contents of silica (SiO2). As-received lignite bottom ash (LBA) and bituminous bottom ash (BBA) were characterized to identify chemical compositions, present phases, particle size distributions, and microstructures by using the techniques of XRF, XRD, SEM, and particle size distribution, respectively. LBA and BBA were ground, dried, and mixed with a commercial alumina (Al2O3) with weight ratios (%) of the commercial alumina: the ground ashes as equal to 70:30 and 50:50, which were used to fabricate ceramic foams via a replica technique. Green foams were sintered in the range of 1250–1450 °C. The experimental results showed that the ground LBA and BBA could be used as raw materials for the ceramic industry. Different properties of phase transformation, sintering temperatures, and compressive strengths were investigated, evaluated, and discussed.