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
Moisture is an important proerty of coal, as all coals are mined wet. Groundwater and other extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held within the c ...
Coal assay techniques are specific analytical methods designed to measure the particlar 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 assay - Chemical properties of coal.
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 ar ...
Relative density
Relative density or specific gravity of the coal depends on the rank of the coal and degree of mineral impurity. Knowledge of the density of each coal ply is necessary to determine the properties of composites and blends. The density of the coal seam is necessary for conversion of resources into reserves.
Relative density is normally determined by the loss of a sample's weight in water. This is best ach ...
Specific Energy
Aside from physical or chemical analyses to determine the handling and pollutant profile of a coal, the energy output of a coal is determined using a bomb calorimeter which measures the specific energy output of a coal during complete combustion. This is required particularly for coals used in steam-raising.
Ash Fusion Test
The behaviour of a coal's ash residue at high temperature is a critical factor in selecting coals for steam power generation. Most furnaces are designed to remove as ...
