charbon de rang bas

OBS: Le rang d'un charbon est sa position relativement à d'autres charbons dans la série de la houillification depuis le lignite tendre (rang bas) jusqu'à l'anthracite (rang élevé). Elle indique sa maturité en fonction de ses propriétés générales chimiques et physiques.

CONT: All fossil fuels from a continuous and progressive series, ranging from lignite, through the various bituminous coals, to anthracite. It is the position of coal in this series that determines its rank. Therefore, lignite is a low-rank coal while anthracite is a high-rank coal.
OBS: rank: The position of a coal relative to other coals in the coalification series from brown coal (low rank) to anthracite (high rank), indicating its maturity in terms of its general chemical and physical properties.