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We explained the pig iron production with blast furnaces by using raw iron or iron ores. In same facility can produces steel also from pig irons with basic oxygen furnaces. In this article, we will explain the production of steel from pig iron basically. We recommend to you read about the production of iron with blast furnaces to understand how the facilities that deals with these kinds of things are working.
Produced pig iron with blast furnaces or other kinds of techniques are transmitted to the basic oxygen furmaces in molten state with special ladles. Actually, the basic oxygen furnace tecnique works as Bessemer process technique. The greatest difference between Bessemer process and basic oxygen furnace technique; in Bessemer, air is blown to the molten pig iron. In basic oxygen furnace, pure oxygen is blown as you see above. It gives much more better result compared with Bessemer process.
At the bottom of the basic oxygen furnace, molten pig iron charge exist. In today’s application, 30% of this charge is from steel scraps that produced in machining processes.
When the pure iron is blown in high velocity to the surface of the molten charge from the lance, combustion occurs at the surface. With this combustion, carbon is dissolved inside the molten iron. Other impurities are also oxidized. Lime(CaO) is also added as fluxing agent for these chemical reactions.
These chemical reactions are;
As you see above chemical reactions inside the basic oxygen furnace, carbonmonoxide and carbondioxide are produced and collected at ‘fume collection hood’ as shown above. The other three of chemical reactions, turn into slag on the molten iron. The carbon content decreases with time linearly, and the desired carbon content for steel can be obtained. Other desired impurities are also added into the molten material that produces from basic oxygen furnace to obtain desired material properties.
The production rate of basic oxygen furnaces is very high that 200 tons of steel can be produced in nearly 20 min.
The most basic explanation of basic oxygen furnaces can be like above. Do not forget to leave your comments and questions about ‘Basic Oxygen Furnaces’ below!