Occurrence and Extraction of Some Metals
1 . Metal Aluminium ( AI ) Occurrence Bauxite – Al2O3 . XH2O Cryolite – Na3AlF6
Common method of extraction Electrolysis of Al2O3 dissolved in molten Na3A1F6 ( neutral flux ).
Neutral flux is the neutral compound added to the ore to decrease its melting point and to make it conducting , e . g ., CaF2 , cryolite ( Na3AlF6 ) etc .
2 . Metal Iron ( Fe ) Occurrence Haematite – Fe2O3 Magnetite – FE3O4
Common method of extraction Reduction of the oxide with CO and coke in blast furnace .
The iron obtained from blast furnace contains about 4 % carbon and many impurities in smaller amount ( e . g ., S , P , Si , Mn ) and is known as pig iron .
Cast iron is different from pig iron and is made by melting pig iron with scrap iron and coke using hot air blast . It has slightly lower carbon content ( about 3 %) and is extremely hard and brittle .