Investigation of the thermal behaviour of coal fly ash by hot stage microscopy

Coal fly ash, a by-product of coal combustion in thermal power plants, offers valuable opportunities for reuse in construction and material engineering. This study explores the thermal behaviour of fly ash samples collected from different sections of the REK Bitola Power Plant. Thermal characteristics of the fly ashes obtained from hot stage microscopy revealed distinct transformation stages, including sintering, softening, and melting intervals. X-ray fluorescence analysis was employed for determination of the chemical composition, while sieve analysis was used for investigation of granulometry of the materials. The physical and chemical characteristics of the ashes, particularly their grain size and content of silica, alumina, calcium oxide, and iron oxide play a crucial role in determining their response to heat. These findings help guide more effective use of fly ash in environmentally friendly applications, supporting waste reduction and promoting sustainable practices.