Lignite, also known as brown coal | Credit: Energy Watch India

Lignite, also called brown coal, is the lowest-rank coal formed from peat at shallow depths and temperatures below 100°C (212°F). It is the first product of coalification, intermediate between peat and subbituminous coal, and appears brownish-black to dark brown in color.

The coal has a calorific value of approximately 17 MJ/kg (4,000-4,600 kcal/kg), significantly lower than higher-rank coals. Ash content ranges from 6-19%, and volatile matter is very high at 45-55% on a moisture and ash-free basis, making lignite easier to gasify and liquefy than higher-rank coals.

#lignite  #gasification  #coaltoliquids  #coal