fly ash

Noun

fly ash (uncountable)

1. A residue generated in the combustion of powdered coal or other materials, comprising the fine particles that rise with the flue gases; when generated industrially it is usually captured and can be recycled for use in construction materials.
   • Heat exchangers should be kept free of debris to minimize the possibility of fire. Fly ash deposited in heat exchangers may cause nonuniform temperatures. Therefore, the exchangers should be disconnected and cleaned out regularly.1956 December, Edmund F. Rasmussen [et al.], “Heating System”, in Inspection and Maintenance of Lumber Dry Kilns and Equipment: Information on Ways and Means of Keeping Lumber Dry Kilns Operating...
   • Among new freight vehicles was a prototype 21-ton wagon with pressure discharge for the conveyance of fly ash from power stations, […]1964 August, “BR [British Rail] in 1963 – ‘We have Turned the Financial Corner’”, in Modern Railways, Shepperton, Surrey: Ian Allan Publishing, →ISSN, →OCLC, page 115

   Synonyms:

   flue ash