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
Coal mining in the United Kingdom at ordinary combustion temperatures (i.e. for the oxidation of carbon - see fossil fuels). The last deep coal mine in the UK closed on 18 December 2015. Twenty-six open cast mines still remain open and Banks Mining said in 2018 they planned to start mining a new site in County Durham. The United Kingdom's onshore coal resources occur in rocks of the Carboniferous age, some of which extend under the North Sea. The carbon content of the bituminous coal present in most of the coalfields is 86% to 88%. Britain's coalfields are associated with Northumberland and Durham, North and South