Combustion By-Products
Coal combustion products have proven to be economical, high quality resources for concrete products, construction, agriculture, and materials industries. The materials often exceed the performance of natural alternatives or those that are man-made. Coal ash is considered to be the nation's fourth most abundant mineral resource, and is environmentally friendly in that its uses are safe and allow the conservation of other scarce natural resources.
These materials — fly ash, bottom ash, cenospheres and FGD (flue gas desulfurization) gypsum — result from the combustion of coal or the treatment of combustion gases. The material is used in structural fill and in land development, buildings, metals recovery, and highways, and to manufacture agricultural fertilizers, carpeting and plastics filler.
| Plant | Location | Dry Fly Ash | Cenospheres | Conditioned Ash+ | Pond Ash+ | Bottom Ash | Gypsum | |
| 1. | Hammond | Georgia | ||||||
| 2. | Bowen | Georgia | ||||||
| 3. | McDonough | Georgia | ||||||
| 4. | Wansley | Georgia | ||||||
| 5. | Yates | Georgia | ||||||
| 6. | Scherer | Georgia | ||||||
| 7. | Branch | Georgia | ||||||
| 8. | Mitchell | Georgia | ||||||
| 9. | McIntosh | Georgia | ||||||
| 10. | Kraft | Georgia | ||||||
| 11. | Scholz | Florida | ||||||
| 12. | Smith | Florida | ||||||
| 13. | Crist | Florida | ||||||
| 14. | Barry | Alabama | ||||||
| 15. | Daniel | Mississippi | ||||||
| 16. | Watson | Mississippi | ||||||
| 17. | Greene County | Alabama | ||||||
| 18. | Gaston | Alabama | ||||||
| 19. | Miller | Alabama | ||||||
| 20. | Gorgas | Alabama | ||||||
| 21. | Gadsden | Alabama |
Fly ash is composed primarily of inorganic, non-combustible minerals such as alumina, silica and iron. It exists as a very finely divided, silt-sized particulate which is removed from combustion gases with various types of collection equipment.
Bottom ash has similar chemical composition to fly ash, although it is larger, generally ranging from sand to gravel size.
Cenospheres are hollow, lightweight spheres formed when gases are trapped in fly ash during the coal combustion process.
Gypsum forms when sulfur dioxide is scrubbed from flue gas. It is similar to mined gypsum in particle size and chemical composition.