STEEL
 
DEFINITION
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    Steel is an alloy of iron that contains little amount of Carbon, Nickel, Chromium, Manganese and     Molybdenum. There are a number of types of steel such as carbon steel, stainless steel, alloy steel etc.     Steel is made from pig iron by reducing carbon and adding small amounts of other metals. These metals     impart particular properties to steel.
MANUFACTURING OF STEEL
 
    Steel is manufactured by a number of processes such as:
Bessemer process (Basic Oxygen Process)
Open hearth process
Electric furnace process
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BESSEMER PROCESS
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    This method is also known as Basic Oxygen Process.
PRINCIPLE OF BESSEMER PROCESS
    In this process impurities in molten pig iron are oxidized and removed by blowing oxygen gas in Bessemer     converter.

                                                        OXIDATION OF PIG IRON
    In this step pure oxygen is blown through the molten pig iron in Bessemer converter. During the oxidation     of pig iron, following changes take place.
OXIDATION OF CARBON
 
    Carbon is converted in to CO2.
C + O2 ®CO2
OXIDATION OF SILICON
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    Silicon is converted in to SiO2.
Si + O2 ®SiO2
OXIDATION OF PHOSPHOROUS
 
    Phosphorus is converted in to P4O10.
4P + 5O2 ® P4O10
SLAG FORMATION
 
    Most of the oxides escape in the form of gases.
    To remove oxides of phosphorus and silicon, CaO (quick lime) is added in the furnace. They are combined     with CaO to produce slag.  
P4O10 + 6CaO ®2Ca3(PO4)2
SiO2 + CaO ®CaSiO3
ADDITION OF METALS
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    Calculated amount of suitable metals such as nickel, chromium or manganese are added to purified     molten iron to form desired type of steel.
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