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8 Cards in this Set

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Lignite
Lowest rank of coal with the lowest energy content. Tend to be relatively young coal deposits that were not subjected to extreme heat or pressure. It crumblies and has high misture content. Anout eight percent of the coal produced in the US is this type of coal and most of it comes from Texas and N. Dakota. It is mainly burned at power plants to generate electricity
Subbituminous
It has a higher heating value than Lignite. This type of coal contains 35 - 45 % carbon, compared to 23 - 35% for Lignite. Most of this coal in the US is at least 100 million years old. Over 40% of the coal produced in the US is this type of coal
Bituminous Coal
Contains 45 - 86% carbon and has two to three times the bituminous coal in the US is between 100 to 300 million years old. It is the most abundant rank of caol found int he US accounting for about half of the US coal production. It is used to generate electricity and is an important fuel and raw material for the steel and iron industries
Anthracite Coal
Contains 86 - 97% carbonand its heating value is slightly lower than bituminous coal. Anthracite is a very rare in the US. The only mines that mine this coal in the US are located in notheastern PA.
How is coal formed
Comes from energy stored by plants that lived hundreds of millions of years ago, when the earth was partly covered with swampy forests. For millions of years a layer fo dead plants at the bottom of the swamps was covered by layers of water and dirt, trapping the energy of the dead plants. The heat and pressure from the top layers helped the plant remains turn into what we today call coal
Surface Mining
Used to produce most of the coal in the US. Used when coal is buryed less than 200 feet underground. In surface mininggiant machines remove the top soil and layers of rock to expose large beds of coal. Once the mining is finished the dirt and rock are returned to the pit, the topsoil is replance, and the area is replanted.
Underground Mining
Sometimes called Deep Mining
Used when the coal is buried several hndred feet below the surface. some underground mines are 1000 feet deep
Amount of coal in US coal reserves
275 Billion short tons
Will power todays country for the next 200 years at are current level of use