Anthracite latter in two or three sizes, all three being above in (38 mm) size on round-hole screens. High grade (HG) and ultra high grade (UHG) anthracite are the highest grades of anthracite coal. They are the purest forms of coal, having the highest degree of coalification, the highest carbon count and energy content and the fewest impurities (moisture, ash and volatiles). High grade and ultra high grade anthracite are harder than standard grade anthracite, and have a higher relative density. An example of a chemical formula for high-grade anthracite would be CHONS, representing 94% carbon. UHG anthracite typically has a
Bituminous coal sub metamorphic compression of peat bog material. Its primary constituents are macerals: vitrinite, and liptinite. The carbon content of bituminous coal is around 60–80%; the rest is composed of water, air, hydrogen, and sulfur, which have not been driven off from the macerals. Bank density is approximately 1346 kg/m³ (84 lb/ft³). Bulk density typically runs to 833 kg/m³ (52 lb/ft³). The heat content of bituminous coal ranges from 24 to 35 MJ/kg (21 million to 30 million BTU per short ton) on a moist, mineral-matter-free basis. Within the coal mining industry, this type of coal is known for releasing the