The four ranks are:Anthracite: The highest rank of coal. …Bituminous: Bituminous coal is a middle rank coal between subbituminous and anthracite. …Subbituminous: Subbituminous coal is black in color and is mainly dull (not shiny). …Lignite: Lignite coal,aka brown coal,is the lowest grade coal with the least concentration of carbon. …
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How many types of coal are there?
There are four major types (or 鈥渞anks鈥? of coal. Rank refers to steps in a slow, natural process called 鈥渃oalification,鈥?during which buried plant matter changes into an ever denser, drier, more carbon-rich, and harder material. The four ranks are: Anthracite: The highest rank of coal.
What determines the rank of a coal?
The rank of a coal is determined primarily by the depth of burial and temperature to which the coal was subjected over time. With increasing temperature, peat is converted to lignite, a very soft, low-rank coal. With further increases in temperature, lignite is transformed into subbituminous coal and then into bituminous coal.
What are the characteristics of coal?
All types of coal contain fixed carbon, which provides stored energy and varying amounts of moisture, ash, volatile matter, mercury, and sulfur.
What type of coal has the lowest carbon content?
Peat exhibits the lowest carbon content (less than 60%) and has an energy density of 15 MJ / kg Figure 2. Lump of lignite or brown coal.