Pulverised fuel ash (PFA) is a waste product of pulverised fuel (typically coal) which is used as an energy source in power stations.
The fuel is pulverised into a fine powder and then mixed with heated air to be burned.
Approximately 18% of the fuel forms fine glass spheres, the lighter of which (± 75%) are borne aloft by the combustion process.
This lighter fraction is typically extracted from the flue gasses by cyclones and electrostatic precipitation.
Depending on the source (mining area) and the makeup of the fuel being burned (traditional or ultramodern methods), the components of the PFA vary considerably, but all PFA contain substantial amounts of silicon dioxide (SiO2), both amorphous and crystalline.
The quantity of silicon dioxide and the presence of other components in PFA determine whether a given PFA can be used in the production of autoclaved aerated concrete (AAC).
Requirements of Flyash for AAC Blocks Manufacturing: