Coal, as we all might know it, is used in the Energy Department, as is mostly used as a combustible. It can be found underground as a sedimentary rock in different layers. Depending on the layer and the age of the deposit, the coal is formed from dead plants which are converted into peat, then in lignite and anthracite. It takes a very long period of time for a peat to develop into anthracite and involves both biological and geological processes.
Regardless the layer may be found in coal is composed from two main substances: carbon and hydrogen. Among these, coal may contain smaller quantities of nitrogen, sulfur and oxygen.
Since its discovery during the history, coal had many uses. It was first used as a fossil fuel for the production of heat and electricity; then it was a resource for industrial fields, such as refining metals.
With the advancement of technology, coal had been processed and exploited within coal mines, which had the main goal to obtain a large quantity of lignite or anthracite for both industrial and energy purposes.
The main types of coal.
- Peat, is considered the very first type of coal and is used mainly within industrial fields. Peat is considered to be highly effective as an absorbent for oil spills on both land and waters.
- Lignite, or mostly known as a “brown coal”, is the considered the lowest quality of the coal. It is mainly used as a fuel to generate electric power.
- Bituminous coal is used also as a fuel in electric-power generation. In early ’60-‘70s it was also used for water heating.
- Anthracite is the most qualitative rank of coal and it is mostly used for residential and commercial space heating
- On the top of the types of coal, la crème-de-la crème is considered the Graphite. It is the most difficult to obtain, and it is mostly used in pencils and, when powdered, as a lubricant.
Underground coal gasification
Underground coal gasification is an industrial process, which converts the coal into gas. The conversion process takes place in non-mined coal seams, using injection of different oxidants. The main purpose of oxidants is to bring the final product resulted from the chemical reaction to surface, which is the gas. This gas is very important and is mostly used as a fuel to generate power, or a chemical feedstock.