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The Formation of Iron and Steel
The Blast Furnace
Step 1 - the formation of sinter
Step 2 - the Blast Furnace
The outer case is a water cooled steel casing that provides the main support for the 30 m high furnace.
Step 2a - the Blast Furnace
The sinter is added through a hopper at the top of the Blast Furnace.The design of the hopper stops gases escaping through the top as sinter is added.
Step 2b - the Blast Furnace
The inner lining is made of insulating bricks, designed to reduce heat loss through the outer walls of the furnace.
Step 2c - the Blast Furnace
The furnace is run continuously for up to 2 years.Air is blasted in at the bottom at point A.
AA
Step 2d - the Blast Furnace
When running continuously, iron is run out through a tap hole, drilled into the furnace at the bottom, B.
AAB
Step 2e - the Blast Furnace
Slag is less dense than iron and floats on the surface.Slag is run out through a second tap hole labeled C.
AAB C
Step 2f - the Blast Furnace
Wasted gases pass out through the top of the furnace, at point D.The hot gases are used to pre-heat the incoming gases at A.
AAB C
D D
Step 2g - the Blast Furnace
Iron that forms in the furnace melts at the temperature of 1700 °C.The iron drips down to the bottom.
AAB C
D D
Equations for the reactions
carbon oxygencarbondioxide
+ →
C(s) O2(g) CO2(g)+ →
This reaction is exothermic and provides the energy needed to heat the furnace.
Equations for the reactions
carbondioxide
carboncarbon
monoxide+ →
CO2(g) C(s) 2CO(g)+ →
The carbon monoxide produced from the carbon dioxide, is the reducing agent which takes the oxygen from the iron(III) oxide.
Equations for the reactions
Iron(III)oxide
carbonmonoxide
ironcarbondioxide
+ +→
Fe2O3(s) 3CO(g) 2Fe(s) 3CO2(g)+ +→
The iron(III) oxide is reduced. Reduction means the iron(III) oxide loses oxygen. The Fe3+ ions gains 3 electrons to form Fe atoms.
Cast IronThe iron from the furnace contains up to 5 % carbon along with other impurities.Cast iron is brittle and has only limited uses such as engine blocks.
Cast iron into steelSteel is made from cast iron. The carbon is removed by passing oxygen through the molten cast iron.When the carbon content has fallen to the required level, other metals are added to form a number of alloys.
Alloys of Steel
Alloys of Steel
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