Coal breaker remaining. The sorting by size is particularly important for anthracite coal. In order to burn efficiently, air must flow evenly around anthracite. Subsequently, most anthracite coal is sold in uniform sizes. In the 1910s, there were six commercial sizes of coal (with the smallest size having three subsets): Coal pieces smaller than in size were considered "culm," and unable to be separated from the impurities (and thus useless). The grade of coal ranged from a low of 5 percent impurities for steam or broken coal to a high of 15 percent for pea-size coal and its subsets. Coal breakers were
Calgon Carbon pond and aquarium cleaning, and removal of impurities during the manufacturing process of vitamins. The company also serves "industrial processes" applications such as liquid chemicals, catalyst support, gas and water processing, ultrapure water, and bio-based chemicals. Activated carbon, which is a small form of carbon with a large pore structure that can remove impurities, was one of the first products produced by the company in the 1940s. Initially manufacturing granular activated carbon (GAC), the company also began producing forms such as powdered, pellets, and later cloth. Pittsburgh Coke and Chemical introduced an early activated carbon system to decolorize sugar in