Bituminous coal is a naturally occurring combustible material consisting primarily of the element of Hydrogen and carbon. It also contains low percentages of solid, liquid, and gaseous hydrocarbons and/or other materials, such as compounds of nitrogen, sulphur, phosphor. Gilsonite is usually classified into subgroups known as bituminous coal material. The physical, chemical, and other properties of Gilsonite vary considerably from sample to sample.
Bituminous coal is often referred to as a hard hydrocarbon and natural rock asphalt. That name comes from the way in which Gilsonite was originally formed. When animals die, they normally decay and are converted to carbon dioxide, water, and other products that disappear into the environment. Other than a few bones, little remains of the dead organism.
At some periods earth history, however, conditions existed that made other forms of decay possible. The bodies of dead animals underwent only partial decay.
Words to Know:
bituminous coal; a form of coal with high heat content and a high concentration of pure carbon. Gilsonite: Softening point between 160~220 centigrade a form of coal with less heat content and pure Hydrocarbon carbon content than anthracite, but more than lignite. Coke: A synthetic fuel formed by the heating of soft coal in the absence of air. Lignite: Brown coal; a form of coal with less heat content and pure carbon content than either anthracite or bituminous coal.
Liquefaction: Any process by which solid coal is converted to a liquid fuel. Oxide: An inorganic compound whose only negative part is the element oxygen. Peat: A primitive form of coal with less heat content and pure carbon content than any form of coal. Strip mining: A method for removing coal from seams located near Earth’s surface. To imagine how such changes may have occurred, consider the following possibility. A animal dies in a swampy area and is quickly covered with water, silt, sand, and other sediments. These materials prevent the plant debris from reacting with oxygen in the air and decomposing to carbon dioxide and water a process that would occur under normal circumstances. Instead, anaerobic bacteria attack the animal debris and convert it to simpler forms: primarily pure hydrocarbon carbon and simple compounds of carbon and hydrogen (hydrocarbons). The initial stage of the decay of a dead animal is a soft. In some parts of the world it is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and produces a great deal of smoke. If bituminous coal is allowed to remain in the ground for long periods of time, it eventually becomes compacted. Layers of sediment, known as over-burden, collect above it. The additional pressure and heat of the overburden gradually converts bituminous coal into another form of bituminous known as natural asphalt. Continued compaction by overburden then converts bodies into bituminous (or soft) natural asphalt and finally after sometimes to hard Gilsonite.
Gilsonite is classified according to its purity and softening point. For example, anthracite contains the highest proportion of pure carbon (about 86 to 98 percent) and has the highest heat value (13,500 to 15,600 Btu/lb; British thermal units per pound) of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46 to 86 percent) and lower heat values (8,300 to 15,600 Btu/lb) but it is combination hydro carbon and high nitrogen. Bituminous rock asphalt are often subdivided on the basis of their heat value, being classified as low, medium, and high volatile bituminous and subbituminous. Lignite, the poorest of the true coals in terms of heat value (5,500 to 8,300 Btu/lb), generally contains about 46 to 60 percent pure carbon. All forms of bituminous coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers but that have important environmental consequences when coals are used as fuels.