Iron ores in the form of hematite (ferrous oxide) and magnetite are removed from the earth through mining. The use of heavy mining equipment is necessary to dig out large pits in an area with a large deposit of iron ore; however, because iron does not occur naturally, it is necessary to use a blast furnace to separate or refine iron from the other substances in the iron ore.
Magnetite and hematite are iron oxides; however, the extraction of iron from an iron oxide involves a series of steps that begins when mined iron ore is crushed into smaller pieces by a crusher and then washed. The second step in the process is calcination or roasting of the ore, which removes certain impurities, carbon dioxide and other substances. Through this process, ferrous oxide also oxidizes to ferric oxide.
The blast furnace reduces iron from the iron oxide, but the complete reduction reaction requires the addition of coke and limestone to the roasted ore. After the completion of different processes in the blast furnace, molten iron flows from the bottom of the blast furnace. This molten iron may be utilized as cast iron.
A high purity iron, such as wrought iron, requires the complete removal of carbon from this iron. Likewise, the steel-making process requires the removal of other impurities like sulfur and phosphorus from molten iron. Many other different types of steel also are fabricated from this molten iron.