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The Ash Industry

The United States ash industry is comprised of electric utilities, marketers and university research institutions that collectively encourage and promote the use of coal combustion products (CCP’s) as beneficial construction materials. CCP’s include fly ash, bottom ash, boiler slag and flue gas desulfurization materials. These materials are produced as a result of burning coal at electric generating stations.
In 2003, an excess of 120 million tons of CCP’s were produced in the United States via 600+ coal fired power plants. CCP’s are the fourth largest mineral resource produced in the United States. It is estimated that CCP production will increase in the future due to the abundance of coal and continued reliance on coal as a primary fuel in power generation.
Fly Ash Over 60% of total CCP production is fly ash. Fly ash is the very fine particulate matter that is captured in an electrostatic precipitator or fabric filter bag house. These fly ash particles would otherwise be released from the smokestack into the atmosphere. Fly ash is most often used in concrete as a replacement for part of the Portland cement.
Bottom Ash Bottom ash is coarser than fly ash and is similar to sand or gravel in texture. Bottom ash is used as an aggregate in concrete and asphalt applications, granular base in pavements, and as a fill material for engineered embankments and fills.
Boiler Slag Boiler slag is a coarse, black, angular, and glassy material that is commonly used for blasting grit, roofing shingles, snow and ice control, etc.
Flue Gas Desulfurization (FGD) - FGD is produced when electric utilities “scrub” gasses coming out of power plant stacks. This process uses calcium carbonate or calcium oxide to remove sulfur dioxide gas from the coal combustion process. FGD is routinely made into synthetic gypsum which can be used as a raw material for wallboard manufacturing.
Benefits to CCP utilization:
- CCP utilization creates revenue for utilities which reduces the cost of electricity.
- CCP utilization reduces disposal activity and corresponding land fill space.
- CCP utilization helps reduce greenhouse gas emissions.
- CCP utilization reduces demand for other natural or manufactured materials.
Common Applications for CCP’s:
- Concrete Products
- Cement Raw Feed
- Flowable Fill
- Structural Fill
- Road Base
- Soil Stabilization and Amendment
- Asphalt Mineral Filler
- Blasting Grit
- Mine Reclamation
- Wallboard
- Waste Stabilization
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