Coal Ash

Coal ash, also referred to as coal combustion residuals or ccrs, is produced primarily from the burning of coal in coal-fired power plants. Coal ash includes a number of by-products produced from burning coal, including:
fly ash, a very fine, powdery material composed mostly of silica made from the burning of finely ground coal in a boiler.
Bottom ash, a coarse, angular ash particle that is too large to be carried up into the smoke stacks so it forms in the bottom of the coal furnace.
Boiler slag, molten bottom ash from slag tap and cyclone type furnaces that turns into pellets that have a smooth glassy appearance after it is cooled with water.
Flue gas desulfurization material, a material leftover from the process of reducing sulfur dioxide emissions from a coal-fired boiler that can be a wet sludge consisting of calcium sulfite or calcium sulfate or a dry powered material that is a mixture of sulfites and sulfates
coal ash is disposed of or used in different ways depending on:
the type of by-product,
the processes at the plant and
the regulations the power plant has to follow.