Fly ash

(redirected from Coal ash)
Also found in: Dictionary, Thesaurus.

fly ash

[′flī ‚ash]
(engineering)
Fine particulate, essentially noncombustible refuse, carried in a gas stream from a furnace.
Coal combustion residue.

Fly ash

A fine glass powder recovered from the gases of burning coal during the production of electricity. It is an ash residue from high-temperature combustion processes. Electric motor plants using western coal produce a nontoxic fly ash that because of its very high calcium content can be a substitute for Portland cement, the common bonding material in concrete, and these micron-sized Earth elements consist primarily of silica, alumina, and iron. When mixed with lime and water, fly ash forms a cementitious compound with properties very similar to that of Portland cement. Because of this similarity, fly ash can be used to replace a portion of cement in the concrete, providing some distinct quality advantages. The concrete is denser, resulting in a tighter, smoother surface with less bleeding. Fly ash concrete offers a distinct architectural benefit with improved textural consistency and sharper detail. Regulations vary from state to state; however, ASTM International suggests that fly ash must not contain more than 6 percent unburned carbon to be used for its cementitious qualities. Substitution of fly ash for Portland cement in concrete is considered a sustainable building strategy, as it reduces the amount of energy-intensive (and CO2-producing) cement in the mix.

fly ash

The finely divided residue resulting from the combustion of ground or powdered coal, transported from the firebox through the boiler by flue gases.

fly ash

as the aggregate.
References in periodicals archive ?
Having the ATIM process in place demonstrates how serious TVA is about safe coal ash storage," said McClung.
The coal ash contains arsenic, lead, selenium and other heavy metals that pose a health risk to people and wildlife when exceeding safety limits set by environmental regulators.
The company has submitted detailed coal ash excavation plans to the North Carolina Department of Environment and Natural Resources (NC DENR) for ash stored at the high-priority Asheville Steam Electric Plant, Dan River Steam Station (Eden), Riverbend Steam Station (Mount Holly) and L.
2, a pipe running under a coal ash pond at Duke's Dan River Steam Station collapsed, coating the bottom of the river with toxic ash up to 70 miles downstream.
According to the sign hanging on Johnson's fence, JEA is the owner of the coal ash.
The proposal would allow alternative performance standards for coal ash disposal units with operating permits issued under an approved state or federal coal ash permit program.
As America's electricity grid changes, the coal ash beneficial use industry is evolving as well," Adams observes.
The clean coal ash was increased first and then decreased.
He also ordered Dominion to submit a new solid waste permit application to the Virginia Department of Environmental Quality for disposal of the ash that includes "corrective measures for the discharge of groundwater and shall not include a plan to cap the coal ash in place.
Silos require cleaning when moisture bonds with the coal ash inside, restricting the downward flow of material to trailer trucks that transport it to landfills or to other facilities for a myriad of reuses.
Duke Energy, an electric power holding company in the United States, is planning to remove coal ash from three basins at the Buck Steam Station in Salisbury, North Carolina and safely recycle the valuable material for concrete.
Over the past 24 months, Royal Mines has been working with one of the world's major gold mining companies in further development of its mining technology process, with one of the world's largest cement companies (a major coal ash consumer) and with a coal ash producer that has over 30 million tons of coal ash in a landfill while it continues to produce another 400,000 tons annually.