Use of oxygen in the steel industry

It is estimated that almost 55% of the artificially produced oxygen is used in the steel industry. Steel is produced by using basic oxygen steelmaking. This method is also called as oxygen converter process or simply as Linz-Donawitz-steelmaking. It is the most extensively used method for steelmaking in which carbon-rich molten pig iron is converted into steel. Oxygen is injected into molten pig iron through a special lance and it lowers the carbon content of the alloy and is converted into low-carbon steel. It is called basic because it uses chemical bases for elimination of impurities and safe guarding line of the converter.

Robert Durrer discovered the method in 1948 and it was commercialized in 1952-53 by Austrian VOEST and ÖAMG. The LD convertor used in the process started using oxygen instead of air. It improved upon the efficiency of the method. The use of the process led to the reduction in capital cost of the plants and time taken in smelting of iron ore besides improving labor productivity. So much so that very big chunk of the steel produced in the world is manufactured using basic oxygen furnace. In 2000, it is estimated that almost 60% of the global production of steel was produced using oxygen converter process.

Though nitrogen and argon are also widely used in steel industry but it is the use of oxygen in steelmaking that plays a crucial role in the production of steel. Moreover, it was the use of oxygen plant in the steel industry that led to the development of air separation plants. Oxygen is used in cast iron and steel production for removal of excessive carbon.

On the other hand, oxygen is also used extensively in converter steel production. It is used for melting zirconium, nickel, lead, zinc and numerous other non-ferrous metals. It is used in electric furnace steel production as well as in blast furnaces with oxygen injection. In non-ferrous metallurgy, it finds application for increasing the rate burning raw material. What is more, it is also used for direct reduction of iron.  

However, nitrogen is also used as a shielding gas in the industry for safeguarding technological processes against ambient air and its oxides. During the vacuum degassing of molten metals, nitrogen is used to create a shielding atmosphere. When continuous steel casting is being done, it is used for creation of an inert atmosphere. Argon is also used in the industry, e.g., steel casting is done in an argon atmosphere.