Fly ash is a substance formed after heating and cooling in the process of coal combustion. Because of the effect of surface tension, most of the fly ash is spherical and the surface is lubricated. The micropores are relatively small, and some of them adhere due to mutual collision in the molten state, becoming honeycomb composite particles with rough surface and more spearheads. The chemical composition and mineral composition of the fly ash are related to the coal combustion composition, fly ash density, boiler type, incineration status and collection method.
The crystals include quartz, mullite, magnetite, etc; Unburned carbon is mostly loose and porous. The standard of fly ash is also divided into national standard grades: Grade I fly ash is 2.6g/cm3. The particle shape of fly ash determines the density of fly ash to a certain extent, and it is related to the iron composition contained in fly ash. The density of fly ash is 1.07 ~ 2.4 g / cm3. Bulk density: generally 555 ~ 700 kg / m3. For different fly ash, they also have their own uses. With the national requirements for sustainable economic development, the utilization rate of fly ash is becoming higher and higher.