Iron is obtained from mines. This is not pure because this also contains other materials besides iron such as oxygen, sulphur etc. Iron mixture obtained from mines is called ore. Iron ore is purified and iron is obtained. Iron ores are the following types:
1) Hematite
2) Magnetite
3) Limonite
4) Siderite
5) Pyrite
1) Hematite:This is represented by the symbol of Fe2O7. This contains 60-65% iron whose specific gravity is from 4.9-5.3. Iron is obtained easily from this. This is found in Bihar, Madhya Pradesh, Mysore and Orissa. Besides it is found in China and America.
2) Magnetite: Its chemical formula is Fe3O4. This contains 70-73 iron. This has magnetic property. It is difficult to purify it. This found in India, Canada, America.
3) Limonite: Its Chemical formula is Fe2O3H2O. This contains 60% iron. This contains 14.5 water also. This found in France, Belgium, Germany and South America.
4. Siderite:Its chemical formula is FeCO3. 40-43% iron is obtained from it. Its specific gravity is 3.85. It is found in England, Australia and Germany.
5) Pyrites:Its chemical formula is FeS2. 47% iron is obtained from it. This contains sufficient quantity of sulphur also. Sulphur is burnt to purify it. This is brittle in nature because of more sulphur.
Classification of Iron
Iron obtained from iron ore can be classified as under.
1) Pig iron
2) Cast iron
3) Wrought iron
4) Steel
1) Pig iron
Iron obtained from blast furnace is called Pig Iron. Various types of iron and steel are prepared out from it. Pig iron is of three types.
a) Grey Pig Iron
b) White Pig Iron
c) Mottled Pig Iron
2) Cast Iron:
It is made out of pig iron. Carbon content is 2% to 4%. Besides impurities like Silicon, Manganese, Phosphorus etc. are mixed. To obtain it cupola furnace is used. Cast iron is of the following types:
a) Grey Cast Iron
b) White Cast Iron
c) Mottled Cast Iron
d) Malleable Cast Iron
e) Alloy Cast Iron
3) Wrought Iron