Metallurgical coal, also called metcoal or coking coal, is a type of coal that is used in the production of steel. It is of a higher purity than thermal coal which is used in energy generation. To make steel, metcoal is heated at around 1100 degrees C to remove water and other chemicals. This is done without the presence of oxygen. The result is a lump of near-pure carbon which is called coke.
The coke is fed into a blast furnace along with raw iron ore and some other minerals called fluxes. This produces pig iron. Pig iron is the basic ingredient to produce steel. Coal therefore plays three roles in the production of steel: a reducing agent, to turn the pig iron to coke; a source of energy to drive the process by breaking apart molecular bonds; and a source of carbon for the final product (steel is an alloy of carbon and iron).