Oxidation Process


BASIC OXYGEN PROCESS
The refining of iron by oxygen lancing was first adopted by professor R.Durer in Switzerland. Latter on, Linz and Downawtiz of Austria developed the basic oxygen process by the year 1950. Oxygen is fed into the furnace through a water cooled lance. The lance is made of three concentric steel tubes to circulate water around the tube and allow oxygen to pass through the inner tube.

OXYGEN BOTTOM BLOWING PROCESS
In this process, oxygen is introduced from the bottom through openings with peripheral shields of protective fluid. This process was also developed in Germany by the year 1967 A.D. This process uses high speed alloy steel. Electro-thermal smelting of iron ore is in practice due to complexities of titanium, vanadium magnetite and other titanium bearing minerals. The increasing cost of cooking coal and non-availability of quality cooking coal makes this Process a commercial proposition. Careful control operation and rigorous routine and maintenance of such furnace is required for proper operation. To improve the operation and minimize the disturbance in production, a proper control device with electrical transformer system is to be installed near the furnace. Such furnace may be fixed type or tilting type. The production capacity of such furnace may vary from 5-30 tons per day. The control and operation system is to be full proof and safety measures are to be there for proper operation of such furnace.
The remaining impurities along with the limestone may form a thin slag above the hot metal. The slag may be further be removed to the slag dump. Then the hot metal is removed to the ladle and may be put into the casting pits. Steel slabs and billets may be produced by casting. After the steel is cooled down, quenching of the steel may be carried out by applying cold water onto the steel products. The converter gas is allowed to burn at the mouth of the converter. The hot gases produced due to the burning of carbon may be reused for generating steam in the captive power plants.

KALDO PROCESS
In the Kaldo process, the refining is carried out in a vessel that is similar in shape and size as that of a LD converter. The vessel has a solid bottom and it is lined with basic fire bricks. The vessel is placed in a cradle and can be rotated around its long axis. The vessel can also be tilted around its various positions to permit charging, tapping and slagging. charge used in this furnace is mostly molten pig iron, scrap and sponge iron. Oxygen is fed through water cooled lance and refining is carried out. Addition of ferroalloys and limestone is also carried out for removal of impurities. Other steps of steel manufacturing are similar to the LD process.

ROTOR PROCESS
The Rotor process was developed in Germany by the year 1952 A.D. A long cylindrical vessel is used for burning most of the carbon monoxide evolved during the refining process. The oxygen lance is dipped into the charge and through which oxygen is blown into the furnace. A secondary lance is inserted and placed above the slag level. These lances are use for burning carbon monoxide. The vessel is mounted on a turn table which can be rotated on a horizontal plane. The table has tapping and deslagging position. The process of steel making is similar to the process used in the LD converter. Alloy steels are produced using the rotor process.


LD PROCESS
The most important basic oxygen process is also known as Linz-Downawtiz process or LD process. In the LD converter, basic grade pig iron is converted into steel by removal of carbon and other impurities. Blowing of pure oxygen into the converter at a very high speed refines the molten pig iron present in the converter. Low carbon steel may be produced by this process. The LD converter is generally lined with basic refractories. Hot molten pig iron is transported by ladles and received in a mixer in the steel melting shop. The mixture functions as a container for the hot metal which may be supplied to the LD converter as per the requirement. The hot metal is shifted to the LD converter and the process of homogenization is carried out .Oxygen is blown into the furnace through the lance. The converter is charged with limestone, ferroalloys, molten pig iron , scrap and sponge iron. Further blowing of oxygen is carried out into the converter. Further addition of ferrosilicon and ferromanganese is carried out for complete removal of impurities. After the formation of the slag, the slag is removed slowly. Then the refining is continued with blowing of oxygen into the hot metal. Little amount of limestone is added for further removal of impurities present in the hot bath.