Coal assay Coal assay Coal analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel. Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal, anthracite and graphite. Each type of coal has a certain set of physical parameters which are mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons) and carbon content. Moisture is an important property of
History of the iron and steel industry in the United States when coke from coal started replacing charcoal as the fuel and reducing agent. Coke has a higher crushing strength than charcoal, allowing larger smelting furnaces. Because iron and steel-making at the time consumed more coal than iron ore, the steel mills moved closer to the coal mines to minimize transportation costs. A problem of coke was that it carried impurities such as sulfur, which degraded the quality of the steel. Although coke quickly became the dominant fuel for iron-smelting, in 1884 charcoal was still used to make ten percent of iron and steel in the US. The use of charcoal