Coal – More Than Electricity – Bottom Ash
This is Part 4 in a Multi-Part Series Examining the Uses for Coal Byproducts.
ALLINACE – Scientists and engineers research, develop and produce new ways of generating energy. In the meantime, coal fired powered plants remain the most abundant producers of electricity world-wide.
Coal does produce a fairly large amount of waste materials. As various research and development industries seek new energy sources, many seek ways to utilize the byproducts of coal burning.
Coal burning byproducts include ashes, slags and flue gas. Bottom ash is the ash too heavy to rise into the upper filtration systems and remains at the bottom of the furnace or boiler. The bottom ash, as with the other byproducts, has various practical uses.
Before being used in construction applications, the metals contained in the bottom ash are removed for use in other areas. The use of a magnetic system attracts the ferrous metals, and nonferrous metals are removed using a magnetic eddy system to separate them from the bottom ash.
A report from the Confederation of European Waste-To Energy Plants (CEWEP) explains ferrous (iron, steel) and non-ferrous metals (such as aluminum, copper and zinc) are separated, and all particles above a certain size are broken down in a crushing facility. The remaining combustible material is then removed.
Then bottom ash is stored for aging in order to improve its quality as a construction material.
The Environmental Protection Agency reported coal ash as one of the largest types of industrial waste generated in the United States.
“Bottom ash production is forecasted to remain steady over the next 20 years, growing slightly from 14.5 million short tons in 2013 to 14.7 million short tons in 2033,” a report the American Road and Transportation Builders’ Association states. The ARTA prepared this report for the American Coal Ash Association in June 2015.
Bottom ash is utilized for a multitude of purposes including road construction, foundation construction, landfill covering and even in art supplies.
In road construction and foundation construction, bottom ash is used as a filler material. It is commonly used in large areas such as parking lots and storage hangars.
In landfills the bottom ash is used as a covering for home and some industrial wastes. This reduces the need for other materials, especially when mixed with crushed glass, which need to be produced for this purpose.
Bottom ash used in this manner has to meet the same standards as the usual covering landfills to control the leeching of heavy metals and other toxins into the ground.
Pigments made with bottom ash are used in airbrush paints as well as in other paints.
The use for bottom ash is wide and versatile making it valuable for a multitude of industries, manufacturers and more.
As the need for electricity grows, the likelihood of increased coal fired plant production is projected to grow, so the need to find uses for byproducts will grow.