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The Fly Ash Resource Center Provides information on Coal Combustion Products (CCPs)

Fossil fuels are used in modern power plants throughout the world to produce electrical energy. The inorganic residue, that remains after pulverized coal is burned, is known as 'Coal combustion products'. Coal combustion products (CCPs)  rapidly accumulate and cause enormous problems of disposal unless a way can be found to utilize these by-products through resource recovery programs. Using coal fly ash conserves energy by reducing the demand for typical pavement materials such as lime, cement and crushed stone, which take energy to produce. Each ton of fly ash used to replace a ton of cement, for example, saves the equivalent of nearly one barrel of imported oil. Coal fly ash can also replace some of the clay, sand, limestone and gravel, and save the energy costs of mining such materials.

Also less greenhouse gases are produced that would otherwise contribute to global warming. Every ton of ash reused in cement products equates to nearly a ton of CO2 savings. Annual cement production contributes 7-8% of global production of greenhouse gases (exceeding commercial airline travel or dairy.)  In the United States, production in 2022 in million short tons were 28.2 coal fly ash, 7.6 bottom ash, 1.6 of boiler slag, 17.3 FGD Gypsum, 7.8 of FGD Materials (wet and dry) and 12.8 FBC ash. 61.9 % of the CCPs in US in 2022 were recycled. See American Coal Ash Association (ACAA) (established in 1968 as National Ash Association) for details. Also see ACAA's "Ash at Work" .

China is the largest producer of coal fly ash in the world. In 2018, it produced 550 million tons.

The production figures in Europe in 2016 were (in million tonnes (metric ton)): 26.8 fly ash, 3.6 bottom ash, 0.52 boiler slag and 0.57 FBC ash. For more information contact  ECOBA (the European Association for Use of By-Products of Coal-Fired Power Stations ); ECOBA member list. See WIN - Wirtschaftverband Mineralische Nebenprodukte e.V." It is the trade association for mineral by-products registered in Germany which is active since January 2016. 

The United Kingdom first used fly ash in dams in Scotland in the 1950's. At one time Britain's coal-fired power stations generated around 10 million tonnes of pulverised fuel ash (PFA) every year.  Nearly a million tons of PFA are used in concrete in Britain each year.  Unfortunately the last coal-fired power plant closed in Sept. 2024. That shortfall will be met with imports and potential use of legacy stockpiles. CDFA (coal derived fly ash) replaces part (typically 25 to 30%) of the concrete's cement content, thus reducing costs. See the United Kingdom Quality Ash Association for more details. 

Canada closed all coal- fired power plants.

Australian coal-fired power stations produced over 12.6 million tonnes of CCPs in 2018. Approximately 6 million tonnes were beneficially used. For information on Australia, see the Ash Development Association of Australia.

For more information on Asia see Asian Coal Ash Association.

See the Israeli Coal Ash Administration whose leading figure was Omri LuLav. Most of the ash in Israel is beneficially used because of his efforts.

 For more information on South Africa see this.

For information on India.

Across the globe , The CCPs production figures in 2015 (million tons) were: USA 117, Europe 105, India 240, China 565, Japan 12.6, Australia 12.2 and Canada 6.2. The utilization rate has also been increasing. See the World Wide Coal Combustion Products Network.

It is the intent of the Fly Ash Resource Center to promote the utilization of CCPs through the dissemination of knowledge, research, and project activities. It is hoped the reader becomes an active participant and shares his/her knowledge and activities. Increased utilization of coal combustion products minimizes disposal costs (costs which are economic and environmental). 

Coal Combustion Products (CCPs)Defined:

Coal Fly Ash is the finely-divided and powdery coal combustion product collected by electrostatic precipitators or baghouses from the flue gases. It is produced from the burning of pulverized coal in a coal-fired boiler. The United States and Canada have different classes of fly ash based on CaO content, See specification section. See quality control section.

Boiler slag and Bottom ash are the heavier and coarser coal combustion products. There are three types of coal-fired boiler furnaces used in the electric utility industry. They are referred to as dry-bottom boilers, wet-bottom boilers and cyclone furnaces. When coal is burned in the most common type, the dry-bottom boiler, 80% leaves as fly ash and 20% as bottom ash. Bottom ash is gray to brown, granular, porous, predominantly sand size minus 12.7mm (½ in) material that is collected in a water-filled hopper at the bottom of the furnace.

Boiler Slag is produced from either the slag-type boiler or the cyclone boiler. In each type, the ash is kept in a molten state and tapped off as a liquid. Both boiler types have a solid base with an orifice that can be opened to permit the molten ash that has collected at the base to flow into the ash hopper below. The ash hopper in wet-bottom furnaces contains quenching water. When the molten slag comes in contact with the quenching water, it fractures instantly, crystallizes, and forms pellets. The resulting boiler slag, often referred to as “black beauty,” is a coarse, hard, black, angular, glassy material.

Flue Gas Desulfurization Gypsum (FGD gypsum) is produced when scrubbers are used to remove SOx from the flue gas streams.

Fluidized Bed Combustion (FBC) ash is produced when coal and other materials are burned together to remove SO2 and SO3.