Fly ash from energy production - a waste, byproduct and raw material

Limited use of biomass has been observed in recent years. The processes of electricity and heat production in conventional boilers and fluidized bed boilers generate waste - mainly fly ash. This waste is traditionally used in many industries. The most important are: mining, production of building materials (including cement) and road construction. The use of fly ash in underground mining (suspension technology) is a method of fly ash recovery, which is typical for the Polish industry. The amount of fly ash (10 01 02) and waste (10 01 82) including ashes from fluidized bed boilers in the year 2012 amounted to 1,490.7 thousand tons. For many years, fly ashes from hard coal combustion in conventional boilers has also been used in various production technologies of building materials, such as: cement, concrete, building ceramics and lightweight aggregates. The ashes from hard coal combustion in fluidized bed boilers are also used in the production of cement and autoclaved aerated concrete. Due to extensive economic use, commercial power plants started to reclassify fly ash from hard coal combustion, turning waste into a by-product after meeting the requirements of the Act on waste of 14 December 2012. The ashes from the co-combustion of biomass are also used. The utilization of fly ash from lignite combustion, both from conventional boilers and fluidized bed boilers, is a cause of concern, while the total recovery of fly ash from the combustion of hard coal and lignite has decreased in recent years. For this reason, studies on the use of traditional fly ash technologies such as the production of building materials and new fly ash technologies such as the use as sorbents in power generation and wastewater treatment, as well as on binding CO2 through mineral sequestration in the Carbon Capture and Utilization, are being carried out.