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