Ad
related to: anthracite vs lignite coal
Search results
Results From The WOW.Com Content Network
Lignite (derived from Latin lignum meaning 'wood'), often referred to as brown coal, [1] is a soft, brown, combustible sedimentary rock formed from naturally compressed peat.It has a carbon content around 25–35% [1] [2] and is considered the lowest rank of coal due to its relatively low heat content.
Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.
The grade of coal produced depended on the maximum pressure and temperature reached, with lignite (also called "brown coal") produced under relatively mild conditions, and sub-bituminous coal, bituminous coal, or anthracite coal (also called "hard coal" or "black coal") produced in turn with increasing temperature and pressure. [2] [22]
Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal, anthracite and graphite.Each type of coal has a certain set of physical parameters which are mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons) and carbon content.
Lignite or brown coal is even worse with a heat of combustion of only 15 MJ/kg, owing to the presence of non-combustible impurities. Bituminous coal has a value lower than anthracite, but neither lignite nor bituminous coal are smokeless owing to their volatiles content.
Its quality is ranked higher than lignite and sub-bituminous coal, but lesser than anthracite. It is the most abundant rank of coal, with deposits found around the world, often in rocks of Carboniferous age. Bituminous coal is formed from sub-bituminous coal that is buried deeply enough to be heated to 85 °C (185 °F) or higher.
This gives information on the carbon, hydrogen and nitrogen composition of the coal, and determines the type of coal: lignite, bituminous coal, or anthracite. Macerals found in kerogen source rocks are often observed under the microscope to determine the kerogen maturity of the sedimentary formations. This is a vital component of oil and gas ...
Sub-bituminous coal is a lower grade of coal that contains 35–45% carbon. The properties of this type are between those of lignite, the lowest grade of coal, and those of bituminous coal, the second-highest grade of coal. [1] Sub-bituminous coal is primarily used as a fuel for steam-electric power generation.