8.22.2006 22:44
The Extraction of Iron
iron is extracted from haematite,iron(III) oxide(Fe2O3)
the iron is extracted in a blast furnace.
iron ore(haematite), coke(carbon) and limestone(calcium carbonate) are put into the top of the blast furnace. hot air is fed into the furnace near the bottom.
the temperature inside the furnace reaches over 16000 degrees celsius at the bottom,where molten iron collects.
the following reactions take place in the blast furnace:
1. the coke burns to produce carbon dioxide and a lot of heat.
carbon + oxygen --> carbon dioxide + heat
C + O2 --> CO2 + heat
2. the limestone is decomposed by heat to produce calcium oxide and more carbon dioxide.
calcium carbonate --> calcium oxide + carbon dioxide
CaCO3 --> CaO + CO2
3. the carbon dioxide reacts with more coke to produce carbon monoxide.
carbon dioxide + carbon --> carbon monoxide
CO2 + C --> 2CO
4. the carbon monoxide reduces the iron(III) oxide to iron.
iron(III) oxide + carbon monoxide --> iron + carbon dioxide
Fe2O3 + 3CO --> 2Fe + 3CO2
5. the calcium oxide is basic. it combines with acidic impurities such as silicon dioxide, SiO2, to
produce slag which is mainly calcium silicate.
silicon dioxide + calcium oxide --> calcium silicate
SiO2 + CaO --> CaSiO3
molten iron collects ar the bottom of the furnace.
slag collect on top of the molten iron. they do not mix.
the slag and molten iron are tapped off separately from the blast furnace.
slag is used in making roads.
