What are the varieties of coal?
Bituminous coal: coal with a higher degree of coalification than lignite, which is characterized by a wide range of volatile yield, and no coking to strong coking in the case of separate coking.Anthracite: coal of high degree of coalification, low volatile, high density, high ignition point, non caking, no smoke when burning.General: hard coal of bituminous coal and anthracite, or a constant temperature (should be constant) ash free calorific value is less than or equal to or greater than 24MJ/kg24MJ/kg but the vitrinite reflectance is equal to or greater than 0.6%.
The rank of coal, also called the rank of coal.Brown coal: a low degree of coal, the appearance of brown, dark luster, containing a high degree of internal moisture and different amounts of humic acid.
Category: coal is divided into major categories according to the degree of coalification and process performance.Category: a further subdivision of the categories according to the nature and purpose of the coal.
