What Happens in the Smelting Furnace?
The job of the smelting furnace is to reduce the metal from its chemically combined state to a metallic state. Iron is a reasonably common substance in the earth, but as any owner of an old car will attest, most of the time it takes the form of rust, iron oxide. In the smelter, iron oxides and other chemically combined forms of iron have their chemical bonds broken. This allows the iron atoms to combine into a mass of metal. Rust goes in; iron comes out. The smelting furnace has two tools to bring about this transformation: heat and carbon. Smelters, like all furnaces, burn carbon fuels to produce heat; that much is obvious. But burning is never complete, and the hot gases within a smelter are rich in carbon that is chemically active. Hot carbon has a strong affinity for oxygen, and the oxygen atoms are literally stripped away from the iron by the gaseous carbon. Left without any chemical partners, the iron atoms form a mass of nearly pure metal.
