Types and Application of coal
Coal is a fossil fuel formed in swamp ecosystems where plant remains were saved by water and mud from oxidization and biodegradation.
Coal is a readily combustible black or brownish-black rock. It is a sedimentary rock, but the harder forms, such as anthracite coal, can be regarded as metamorphic rocks because of later exposure to elevated temperature and pressure.
It is composed primarily of carbon along with assorted other elements, including sulfur. It is the largest single source of fuel for the generation of electricity world-wide, as well as the largest source of carbon dioxide emissions, which is the primary cause of global warming.
Coal is extracted from the ground by coal mining, either underground mining or open pit mining.
Types of Coal
As geological processes apply pressure to peat over time, it is transformed successively into the following types of coal.
Lignite also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for steam-electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.
Sub-bituminous coal whose properties range from those of lignite to those of bituminous coal and is used primarily as fuel for steam-electric power generation.