Fly ash, also known as coal ash or "pulverized fuel ash" in the United Kingdom, is one of the coal combustion products, composed of the fine particles that are driven out of the boiler with the flue gases. Ash that falls in the bottom of the boiler is called bottom ash. It is a general name used for the residual products of combustion that rise with flue gases.
Fly ash is also called coal ash, it is widely used in many fields. However, the wide application of fly ash also increases the risk of environmental pollution. The common pollution contains groundwater contamination and air pollution. Therefore, it is important to find a good way to store it to prevent environmental pollution.
Chemically and physically, fly ash can have many forms, these depend on the type of fuel combustion and treatment methods. Typical fly ash contains a significant amount of silicon dioxide and calcium oxide, which make it frictional and abrasive. Usually, fly ash has a fine particle size distribution with most less than 100 microns. Given the fine particle size, frictional nature and high temperature, fly ash can be a material hard to handle. In modern coal-fired power plants, fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before the flue gases reach the chimneys.Together with bottom ash removed from the bottom of the boiler, it is known as coal ash.