Copyright © 2003 -2008 Roger Philpot All Rights Reserved
Images © 2008 Roger Philpot
Between 200 and 300 million years ago, long before there were any reptiles, birds or mammals, in many parts of the world there existed warm and human climatic conditions. These conditions favored the growth of huge tropical ferns and giant trees, which grew and died in vast swamp areas. The dead plants fell into the boggy waters, which tended to exclude oxygen and bacteria, so that they only partially decomposed to produce a peat-like material. This fossilized plant debris was the beginning of coal, but only the beginning.
Vegetation continued to grow for many generations and centuries, forming vast, thick peat beds which were later to turn into coal. After a time the areas of swamp gradually became submerged by shallow seas, where they were covered by sediment. these sediments would later become sedimentary rock. This cycle of swamp followed by submersion was often repeated a number of times, so that a sequence of horizontal bands of peat and inorganic, sedimentary rock was built up. This formed the first stage, called the biochemical stage. Coal formation occurred in other geologic periods as well.
Subsequently, the bands of peat were altered by the action of pressure and temperature during the second, or geochemical stage, to form the various kinds of coal found today. As much as a 20-fold reduction in the thickness of the original plant deposits sometimes occurred. During the course of time these horizontal coal seams were further altered as they became folded, tilted and eroded. Much of this action was due to the motion of the continents, as mountains formed and were then worn away. The study of fossils is called paleontology. The creation of coal from fossils is part of geology.
Coal is our most abundant fossil fuel resource. Coal is a complex mixture of organic chemical substances containing carbon, hydrogen and oxygen in chemical combination, together with smaller amounts of nitrogen and sulfur. This organic part of coal has associated with it various amounts of moisture and minerals Coalification is the name given to the brown coal, sub-bituminous coal, bituminous coal, and anthracite.
There are two primary methods of mining coal, surface mining and underground mining. There are over 1,000 surface mines and more than 1,000 underground mines in the US. Underground mining is more difficult and requires more miners, but much of our best coal is underground. Mining has become much safer and more efficient over the years. In 1980 there were over 220,000 coal miners in the country. Today there are fewer than 100,000. But while 1980 production was about 800,000 tons, today we produce over 1 billion tons with fewer than half the number of miners.
Coal that is going to be burned in solid form may go through a variety of preparation processes. The simplest of these is removing foreign material and screening for size. Large pieces may be crushed, or the whole mass pulverized to a certain size. Coal can also be washed or cleaned to remove contaminants. It is also possible to turn solid coal into a gas or liquid fuel, but these are much more complex processes, sometimes called clean coal technologies. Coal that is going to be used in steel making is processed into coke.
Domestically, coal is moved primarily by barge and rail, although it may initially move by truck from the mine. About one billion tons per year. In many cases it is transported long distances, for one of two reasons. First, a particular type of coal may be needed far from where it is found. Examples include coal with a low sulfur content that reduces sulfur dioxide emissions, and special coal used to make steel. Second, a lot of coal is burned to make electricity in places where no coal is found locally, so it has to be brought in. In addition, some coal is exported by ship, mostly for steel making in other countries.
The Black Diamond
Coal Creation
About Coal
Coal Mining
Coal Processing
Coal Transport
Inside The Coal Mines
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The Black Diamond
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