Bituminous coal

Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. It is typically hard but friable. Its quality is ranked higher than lignite and sub-bituminous coal, but lesser than anthracite. It is the most abundant rank of coal, with deposits found around the world, often in rocks of Carboniferous age. Bituminous coal is formed from sub-bituminous coal that is buried deeply enough to be heated to or higher. Bituminous coal is used primarily for electrical power generation and in the steel industry. Bituminous coal suitable for smelting iron (coking coal or metallurgical coal) must be low in sulfur and phosphorus. It commands a higher price than other grades of bituminous coal (thermal coal) used for heating and power generation. Within the coal mining industry, this type of coal is known for releasing the largest amounts of firedamp, a dangerous mixture of gases that can cause underground explosions. Extraction of bituminous coal demands the highest safety procedures involving attentive gas monitoring, good ventilation and vigilant site management. Bituminous coal is a particular rank of coal, as determined by the amount and type of carbon present in the coal and the amount of energy it can produce when burned. It is higher in rank than sub-bituminous coal but lower in rank than anthracite. Bituminous coal is the most abundant rank of coal. Coal rank is based on several characteristics of the coal. The fixed carbon content refers to the percentage of the coal that is neither moisture, nor ash, nor volatile matter. When evaluated on a dry, mineral-matter-free basis, the fixed carbon content is the fraction of the coal that is not volatile organic matter. An agglomerating coal is a coal that softens when heated, forming a hard, gray, porous coke that resists crushing. Vitrinite reflectance is a measure of how reflective a polished surface of an average particle of vitrinite in the coal is.