The majority of pig iron produced by blast furnaces undergoes further processing to reduce the carbon content and produce various grades of steel used for construction materials, automobiles, ships and machinery. Although the efficiency of blast furnaces is constantly evolving, the chemical process inside the blast furnace remains the same.
The more advanced way to smelt iron is in a blast furnace. A blast furnace is charged with iron ore, charcoal or coke (coke is charcoal made from coal) and limestone (CaCO 3 ). Huge quantities of air blast in at the bottom of the furnace, and the calcium in the limestone combines with the silicates to form slag.