Coal Combustion Products
Coal Combustion By-Products (CCBs) are the incombustible inorganic
matter in coal that is leftover after the burning process. These
materials produced primarily from the combustion of coal in coal-fired
power plants. These by-products include:
Flue gas desulphurisation gypsum
Coal combustion products (CCPs) can play an important role in
concrete production. The characteristics and physical properties of
CCRs vary. In general, the size, shape, and chemical composition of
these materials determines their beneficial reuse as a component of
building materials or as a replacement for other virgin materials such
as sand, gravel, or gypsum.
1. Fly Ash:
(60 percent of all coal combustion waste)
Fly ash is comprised of tiny particles removed from our
flue gas by emissions control devices.
Fly ash can be used to replace or supplement cement in
concrete. It produces a concrete that is strong and durable,
with resistance to corrosion, alkali-aggregate expansion,
sulphate and other forms of chemical attack.
Among the most significant environmental benefits of
using fly ash over conventional cement is that greenhouse
gas (GHG) emissions can be significantly reduced.
Fly ash also serves as filler in wood and plastic products,
paints and metal castings.
2. Bottom Ash:
(12 percent of all coal combustion waste)
Bottom ash is made up of larger particles, such as sand and
small rocks within the coal, collected in the bottoms of
Bottom ash is used to manufacture cement or to replace
native materials in landfill construction.
3. Flue-gas Desulfurization Gypsum :
(24 percent of all coal combustion waste)
Flue-gas desulfurization (FGD) materials are produced by
chemical “scrubber” emission control systems that remove
sulfur and oxides from power plant flue gas streams.
FGD gypsum is used in agricultural applications to treat
undesirable soil conditions and to improve crop
FGD materials are used in mining and land reclamation
4. Boiler Slag:
(4 percent of all coal combustion waste)
These molten ash collected at the base of furnaces that is
quenched with water and shatters into smooth, glassy black
particles. It is a by-product produced from a wet-bottom
It can be used as a raw feed for manufacturing portland cement
clinker, as well as for skid control on icy roads.
Boiler slag is also used for roofing granules and as blasting grit.