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.