For making iron-most, are the essential features of coke ovens and the blast furnace, where coke is produced from coal and iron ore is melted (reduced) to produce pig iron, respectively. The furnace is charged from the top with iron ore, coke and limestone; A hot air, frequently enriched with oxygen, blown in from the bottom; and the carbon produced from the coke transforms the iron ore into pig iron containing carbon, with the generation of carbon monoxide and carbon dioxide. The limestone acts as a flux. At a temperature of 1,600 ° C, the pig iron melts and collects at the bottom of the furnace. The furnace is tapped (ie the pig iron is removed) periodically, and pig iron is cast into pigs for later use (eg in foundries), or is poured into ladles where it is transferred, still molten, to the steel making plant. The waste gas from the blast furnace, which is rich in carbon monoxide, burned in blast furnace stoves to heat the air blown into the furnace and may be used as a fuel elsewhere in the steel plant.
Some pig iron is also produced in foundry cupola furnaces. Various processes exist or are under development for producing iron through the direct reduction of iron ore, using reducing gases. Such processes may be more important in the future.
The purpose of operations aa steel refine the pig iron which contains large amounts of carbon and other impurities. The need to reduce carbon content, the impurities oxidized and removed, and the iron converted into a highly elastic metal that can be forged and fabricated. Alloying agents may be added at this stage. Different types of melting furnace used in this process.
Some steel is produced directly from scrap or other materials containing iron, most often in electric arc furnaces, without the need for iron ore or coke.
Steel is cast into slabs, billets, bars, ingots and other shapes. A scarfing, pickling, annealing, hot and cold rolling, extrusion, galvanizing, surface coating, cutting and slitting, and other operations designed to produce a variety of steel products including subsequent steps.