The ultimate goal in producing steel is purity. Heart valves, I-beams and airliner manufacture.

Three primary installations (click here) in an integrated steel plant are the blast furnace, the steel furnaces, and the rolling mills. The blast furnace converts iron ore to pig iron; the steel furnaces convert the pig iron to steel; and the rolling mills shape the steel into sheets, slabs, or bars.

Blast furnace. A blast furnace is a chimney-like structure in which iron ores (mainly FeO, Fe 2 O 3 , and Fe 3 O 4 ) are converted into iron metal. Iron ore, coke, and limestone are loaded into the top of the furnace, while air is blown in from below. The coke is converted to carbon monoxide (CO), which then acts as the reducing agent:

2 C + O 2 → 2 CO

3 CO + Fe 2 O 3 → 2 Fe + 3 CO 2

The molten iron falls to the bottom of the furnace, and the limestone reacts with silicate impurities to form a molten slag, which floats on top of the iron. The two layers are drawn off separately, and the iron is poured into molds. Because the molten iron yields ingots that resemble little pigs, the product is referred to as "pig iron."...

Example: Nonsulferized carbon steels (click here)