The Different Types Of Coal

March 14, 2011
Coal is a dark sedimentary rock primarily composed of carbon along with quantities of oxygen, nitrogen, hydrogen and to a large degree, sulfur. All in all there are four different types or “ranks” of coal, each with their own special attributes. Their weight, their content, their own use. Find out what they are below and be sure to tune in for the premiere of Spike’s new original series, Coal on Wednesday, March 30 at 10PM/9c to not only learn more about what coal is, but also how it’s put to use.

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The youngest of the coals, lignite also has the lowest carbon content, only 25-25 percent. Sometimes labeled “brown coal,” it is used almost exclusively for electric power generation. Lignite has a heat value that ranges between 4,000 and 8.300 BTUs-per-pound. Each BTU (British Thermal Unit) is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. This rank of coal is found and mostly mined in Texas. Additionally, lignite can be found in Montana, North Dakota, and some of the Gulf Coast states.

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This is the most plentiful form of coal in the United States. Chiefly used to generate electricity and make coke for the steel industry, bituminous coal has a carbon content ranging from 45-86 percent carbon and a heat value of 10,500 to 15,500 BTUs-per-pound. It is part of the fastest growing market for coal -- supplying heat for industrial processes. However, this still remains a relatively small market for the fossil fuel.

Sub-Bituminous Coal – The reserves for this particular form of coal are located in the Western states as well as in Alaska. Ranking below its coal brother, bituminous, in terms of moisture, sub-bituminous also clocks in with a smaller 35-45 percent carbon content. Additionally, its heat value brings in only 8.,300 to 13,000 BTUs-per pound. It is often looked at as a cleaner coal as it generally has a lower sulfur content to go along with its slightly lower heat value. Primarily, it is used for steam-electric power generation.

Photo: Dorling Kindersley/Getty Images

Discovered in 1769, this form of coal has the highest carbon content, close to 86 and 98 percent. As the hardest of the four types, it also has a heat value of nearly 15,000 BTUs-per-pound. That is roughly one and a half times as much heat as the same volume of oil and four times as much as firewood. With upwards of 7.3 billion tons of anthracite reserves in the United States, it is found mostly in the 11 northeastern-most Pennsylvania counties. The coal itself is usually used to heat homes as it burns cleanly, does not produce volatile gases and doesn’t deteriorate, allowing it to be stored for long periods of time without any environmental problems.

The Cobalt Coal mine itself is a metallurgical mine that employs pillar mining (entering the bottom of a mountain horizontally and cutting channels through rock that measures a mere 36 to 48 inches in height). They uncover bituminous coal, which as mentioned is used primarily for making steel.

As part of your continuing education on coal and the coal industry, tune in to the series premiere of Spike TV’s Coal on Wednesday, March 30 at 10PM/9c and follow the show on Facebook and Twitter for all the latest updates and exclusive content and previews.