18-12-2012, 06:54 PM
Blast Furnace
Reduction:
Calcinated or roasted ore is then reduced to metallic state by any one of the following way depending upon the type of reducing agent for
Smelting Alumino-thermic reduction Electrolytic reduction
Smelting porcess :
1.It is reduction of metal oxide with carbon or its compound
like CO, CO2, Charcoal etc at high temp
2. Calcinated and roasted ore is mixed with coke and flux (8:4:1) and heated in blast furnace in presence of air supply
3. Reducing agent convert ore in to oxide and flux remove gangue in the form of fusible mass.
What is a Blast Furnace?
The purpose of a blast furnace is to reduce and convert iron oxides into liquid iron called "hot metal".
The blast furnace is a huge, steel stack lined with refractory brick.
Iron ore, coke and limestone are put into the top, and preheated air is blown into the bottom.
Why does Iron have to be extracted in a Blast Furnace?
Iron can be extracted by the blast furnace because it can be displaced by carbon.
This is more efficient method than electrolysis because it is more cost effective
The Method
Three substances are needed to enable to extraction of iron from its ore. The combined mixture is called the charge:
Iron ore, haematite - often contains sand with iron oxide, Fe2O3.
Limestone (calcium carbonate).
Coke - mainly carbon
The charge is placed a giant chimney called a blast furnace. The blast furnace is around 30 metres high and lined with fireproof bricks. Hot air is blasted through the bottom.