Steel making is the process where oxidation of impurities takes place. The slag is formed and separated after constant blowing of oxygen through the molten metal.
During the steel making, the impurities are oxidized to their respective oxides. The oxides are separated as gas and slag. But the sulphur and phosphorus are separated by
reduction process from the molten iron. The oxygen is used as oxidizing and refining agent. The quality of steel improves if the refining is carried out properly. The process
of steel making includes a number of steps. The steps are charge preparation, melting, refining, tapping, deoxidation, recarborisation, alloying, teeming and stripping.
History Of Steel Making
The Bessemer process of steel making is the first process of large scale steel making. This process was developed by Henry Bessemer of U.K in the year 1860 a.d. By blowing cold air through
molten iron steel was produced.
Latter on, Robert Muschet improved this process and developed the use of ferro-manganese to produce quality steel. Thomas of Germany modified this process and developed the basic steel making process in the year 1878.Under this process, impurities like phosphorous and sulphur can be removed along with other impurities. The Siemen's -Martin's process or the open hearth process was developed by the year 1861.The initial open hearth process was acidic in nature. By 1868, basic open hearth process was also developed. The basic open hearth process is still in use in many steel plants. In the latter stage, the oxygen steel making process became very popular for producing quality steel. Towards the end of 1890, the electric arc furnace was developed for steel making in small and medium scale units. This process was developed by Paul Herould. Ferranti developed the electric induction furnace by the year 1900. Both these processes use steel scrap and sponge iron as the raw material for production of steel.
The use of oxygen by Linde-Frankle process became popular after 2nd world war. New processes of steel making using oxygen became very popular. These are LD process, Kaldo process and Rotor process. Later on, the basic oxygen furnace was developed for producing quality steel. To meet the demand of special steel, secondary steel making process like Laddle process, decarboburisation process, remelting process and tundish metallurgical process were developed. The LD process was modified and a new process known as bathagitated process or BAP was developed. Other new processes like continuous steel making process and spray steel making process are developed .Large scale integrated steel plants are established to produce mild steel for meeting growing demand of structural steel. For producing alloy steel, electric arc furnace and induction furnace are established in small and medium scale.