Coal ash is the coal combustion byproduct or waste that remains after coal is burned. Coal Ash is formed when the coal boiled in burners generates steam. Approximately 95% of the ash retained falls are three types of materials that fall into the category of 'coal ash' or 'coal byproduct': fly ash, bottom ash, and boiler slag.
In addition to tecnhologically-enhanced, naturally-ocurring radioactive materials (TENORM) such as: uranium and radium, coal ash also contains over a dozen heavy metals. Toxic metals such as arsenic, lead and mercury are found in coal ash along with silicon, aluminum, iron and calcium.
Most coal ash is disposed of in landfills, while approximately 20 percent is used in building, road and construction materials. (Source: EPA / Photo: