Coal Classification

Lignite*

Lignite is formed from peat which has dried and hardened due to heat and pressure from overlying alluvial deposits. Often referred to as ‘brown coal’, it has higher moisture and lower calorific values than higher-rank coals. It is, however, an important source of energy for generating electricity.

Sub-bituminous*

Sub-bituminous coal is formed when lignite is subjected to increased temperatures and pressures due to deeper burial. It is a black coal with a higher thermal value than lignite. It is used primarily for generating electricity and for heating, and also as a source of aromatic hydrocarbons for the chemical industry.

Bituminous*

Bituminous coal is formed in subterranean temperatures of up to 180°C, as sub-bituminous layers become subjected to deeper burial. It is usually divided into three sub-groups: low volatile, mid volatile and high volatile. Depending on its characteristics, bituminous coal can be used for electricity generation or for the production of iron, steel and other metals. It is commonly referred to as ‘hard coal’. When used to produce metal, it is known as ‘coking coal’.

Anthracite

Glossy black in appearance, anthracite is formed as a result of extreme pressure and heat within folded strata. Anthracite has a high calorific value due to its high content of fixed carbon. It is used for electricity generation, and for domestic and commercial heating.