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 breaker rolled down a chute and then through an inclined cylindrical screen. The screen had a mesh which was fine toward the front and became progressively less so toward the end. Larger chunks of coal, falling inside the cylinder as it rotated, broke up and eventually passed through the screen. Impurities, which were heavier, tended to exit the breaker at the end of the screen. The sorted coal would then be collected in bins below the screen, and transported to market. A fellow Pennsylvanian, Gideon Bast, licensed the technology from Battin, and erected the first commercial coal breaker in Schuylkill County,