Coal is a sediment rock, and a complex colloidal system in solid-state physics. It is an intriguing object for chemical and physical analyses. It is a physically and chemically combustible heterogeneous sedimentary rock consisting of both organic and inorganic components.
Organically, it consists of carbon, hydrogen, and oxygen, with some amounts of sulfur and nitrogen. Inorganically, It consists of a wide range of ash-forming compounds distributed throughout the coal. The inorganic constituents can vary in concentration from several percentage points down to parts per billion of the coal depending upon the coal quality.
Origin of Coal
Coal is found in deposits termed as seams that originated through the accumulation of vegetation remains that has undergone physical and chemical changes under intense temperature and pressure condition. These changes include:
- The decay of the vegetation.
- The deposition and buried by sedimentation.
- The transformation of the plant remains into the organic rock.
Coal Formation Theories
- In-situ theory (autochthonous process)
- Drift theory (allochthonous origin)
1. In situ Theory
According to this theory, plants grew and decayed in the same area where coal exists today. Numerous fossil tree trunks and fossil roots in the coal seams are proof of this in-situ theory.
2. Drift Theory
According to this theory, the vegetable matter got carried away by flowing water bodies into the neighboring lagoons, lakes, and estuaries. Fossil tree stems in the coal seams without attached roots are proof of this theory.
Uses of Coal
The major uses of coal are listed below:
- As fuel for electricity generation
- Production of coke
- Gasification to produce syngas
- Production of chemicals
- Cultural usage