Anthracite Coal

Anthracite Coal

• Anthracite, also called hard coal, the most highly metamorphosed form of coal.

• It contains more fixed carbon (86 percent or greater on a dry, ash-free basis) than any other form of coal and the least amount of volatile matter (14 percent or less on a dry, ash-free basis), and it has calorific values near 35 megajoules per kilogram, not much different from the calorific values for most bituminous coal.

• Anthracite is the least plentiful form of coal.

Anthracite is considered “nonclinkering” and free-burning because when it is ignited it does not "coke" or expand and fuse together. It is most often burned in underfeed stoker boilers or single-retort side-dump stoker boilers with stationary grates. Dry-bottom furnaces are used because of anthracite's high ash fusion temperature. Lower boiler loads tend to keep heat lower, which in turn reduces nitrogen oxide emissions.

Inferior coal rejected from anthracite mines is called culm. This has less than half the heat value of mined anthracite and higher ash and moisture content. It is used most often in fluidized bed combustion boilers.

SPECIFICATION