Write down all the four varieties of coal in order of their increasing carbon content (with carbon %)
Answers
Answer:
Rank
(From Lowest
to Highest)
Properties
Peat
A mass of recently accumulated to partially carbonized plant debris. Peat is an organic sediment. Burial, compaction, and coalification will transform it into coal, a rock. It has a carbon content of less than 60% on a dry ash-free basis.
Lignite
Lignite is the lowest rank of coal. It is a peat that has been transformed into a rock, and that rock is a brown-black coal. Lignite sometimes contains recognizable plant structures. By definition it has a heating value of less than 8300 British Thermal Units per pound on a mineral-matter-free basis. It has a carbon content of between 60 and 70% on a dry ash-free basis. In Europe, Australia, and the UK, some low-level lignites are called "brown coal."
Sub Bituminous
Sub bituminous coal is a lignite that has been subjected to an increased level of organic metamorphism. This metamorphism has driven off some of the oxygen and hydrogen in the coal. That loss produces coal with a higher carbon content (71 to 77% on a dry ash-free basis). Sub bituminous coal has a heating value between 8300 and 13000 British Thermal Units per pound on a mineral-matter-free basis. On the basis of heating value, it is subdivided into sub bituminous A, sub bituminous B, and sub bituminous C ranks.
Bituminous
Bituminous is the most abundant rank of coal. It accounts for about 50% of the coal produced in the United States. Bituminous coal is formed when a sub bituminous coal is subjected to increased levels of organic metamorphism. It has a carbon content of between 77 and 87% on a dry ash-free basis and a heating value that is much higher than lignite or sub bituminous coal. On the basis of volatile content, bituminous coals are subdivided into low-volatile bituminous, medium-volatile bituminous, and high-volatile bituminous. Bituminous coal is often referred to as "soft coal"; however, this designation is a layman's term and has little to do with the hardness of the rock.
Anthracite
Anthracite is the highest rank of coal. Unlike other types of coal, it is usually considered to be a metamorphic rock. It has a carbon content of over 87% on a dry ash-free basis. Anthracite coal generally has the highest heating value per ton on a mineral-matter-free basis. It is often subdivided into semi-anthracite, anthracite, and meta-anthracite on the basis of carbon content. Anthracite is often referred to as "hard coal"; however, this is a layman's term and has little to do with the hardness of the all coals