Formation mechanism and applications of cenospheres: a review

In thermal power plants, pulverized coal combusts to give an intricate composition of anthropogenic materials such as fly ash (coal). These materials are a major threat to environmental (air and water, etc.) pollution if dispose of to landfill sites and rivers. Since the last two decades, research and efforts are going on to reduce production and derivation of potentially valuable materials from coal fly ash such as cenosphere. Cenosphere is a low density, chemically inert and spherical material filled with air/inert gas (either nitrogen or carbon dioxide). Cenosphere is considered to be the most important fraction of fly ash as it is being used in different industries due to its condescending properties such as high workability, thermal resistance, compressive strength and low conductivity, bulk density. This review discuses the extraction of cenosphere from fly ash, its characterization (physical and chemical) and applications in different industries.