Coal Combustion Product (CCP) Production and Use

Abstract

During 1996, approximately 800 million metric tons (870 million short tons) of coal were burned to generate electricity. As a result, over 90 million tons (100 million short tons) of coal combustion products (CCPs) were generated by the electric utilities. The American Coal Ash Association (ACAA) conducts an annual voluntary, confidential, survey of U. S. coal fired electric utilities to gather data about the production and use of CCPs. The CCPs data gathered by ACAA includes information on the production and use of fly ash, bottom ash, boiler slag, and flue gas desulfurization (FGD) material. For the period from 1966 to 1996 CCP production increased steadily as more coal was burned by the electric utilities. In 1996, fly ash accounted for 58% of the CCPs produced, while FGD material and bottom ash accounted for 23% and 16% respectively. The use of fly ash has steadily increased during the same period increasing from 2.8 million metric tons (3.1 million short tons) in 1966 to 22.8 million metric tons (25 million short tons) in 1996. The overall percentage of CCPs used has increased from 12.3% in 1966 to more than 30% (25% including FGD) in 1996. Different types of CCPs exhibit distinct chemical and physical properties, making each one suitable for particular applications. Fly ash has a silt like texture and is a pozzolan. The largest volume use of any one CCP is the use of fly ash in cement, concrete and grout. In the future, increases in the production of fly ash and bottom ash will be proportional to the increase in coal use for electric power production. An increase in coal burn will lead to an increase in production of CCPs. The largest growth in CCP production is expected to be in the form of increasing amounts and types of FGD materials.