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Coal is a carbon-containing rock formed by the decay of ferns, vines, trees and other plants which flourished in swamps millons of year ago and subsequently became buried. Over time, the actions of bacteria, heat and pressure transformed the buried plant debris first into peat (a precursor of coal) and then into the various types of coal as we know them today.[1][2][3]
Because of the various degrees of transformation that occurred during the forming of coal deposits in different locations, the composition of coal coal varies from one coal deposit to another. No two coals are the same in every respect. In general, coal consists of carbon, hydrogen, oxygen, nitrogen, sulfur and mineral matter (including compounds of silica, aluminum, iron, calcium, magnesium and others).
Types of coal and coal assays
(Work on this sectionjis in progress)
Coal as a fuel
Due to its relatively high carbon content and solid, easily-handled form, coal is used for fuel, and has been for hundreds of years (see history of coal mining).
Other uses of coal
Coal can be converted to coke by destructive distillation (called coking), which alters the physical properties to provide a more uniform and more combustible product. Coke is used in making steel, smelting of iron, the production of phosphorus and the production of calcium carbide.
Coal can be converted, by a process known as coal gasification, into a gas with the same heat of combustion as natural gas and referred to as synthetic natural gas (SNG). Coal gasification can also produce so-called syngas with a heat of combustion that is much lower than that of natural gas.
Refs
- ↑ Green, Don W. and Perry, Robert H. (Editors) (1997). Perry's Chemical Engineers' Handbook, 6th Edition. McGraw-Hill. ISBN 0-07-049479-7.
- ↑ Eugene A. Avallone, Theodore Baumeister and Ali Sadegh (Editors) (2006). Marks' Standard Handbook for Mechanical Engineers, 11th Edition. McGraw-Hill Professional. ISBN 0-07-142867-4.
- ↑ Frank Kreith (Editor) (1998). The CRC Handbook of Mechanical Engineering, 1st Edition. CRC Press. ISBN 0-8493-9418-X.