Extraction of Copper :
(a) `text(Ores)` : Copper pyrites `CuFeS_2`; Cuprite or ruby copper `Cu_2O`; Copper glance `Cu_2S`; Malachite `Cu` `(OH)_2 *CuCO_3`; Azurite `Cu (OH)_2*2CuCO_3`.
(b) `text(Process)` : See fig.
(c) `text(Reactions)` :
(i) `text(Roasting)` : `2CuFeS_2 + O_2 -> Cu_2S + 2FeS + SO_2`
`2FeS + 3O_2 -> 2FeO + 2SO_2`
`2Cu_2S + 3O_2 -> 2Cu_2O + 2SO_2`
(ii) `text(Smelting)` : `Cu_2O + FeS -> Cu_2S + FeO`
`FeO + SiO_2 -> FeSiO_3`
(iii) `text(Bessemerisation)` : `2FeS + 3O_2 -> 2FeO + 2SO_2`
`FeO + SiO_2 -> FeSiO_3`
`2Cu_2S + 3O_2 -> 2Cu_2O + 2SO_2`
`Cu_2S + 2Cu_2O -> 6Cu + SO_2` (self reduction)
(iv) `text(Poling)` : Molten `Cu` is stirred with poles of green wood to reduce any copper oxide in Copper.
(v) `text(Electrolytic refining)` : Anode - impure `Cu`; cathode - pure `Cu`; electrolyte `CuSO_4 + H_2SO_4`.
`text(Note)` : Low gread copper can be extracted by hydrometallurgical process also.
(b) `text(Process)` : See fig.
(c) `text(Reactions)` :
(i) `text(Roasting)` : `2CuFeS_2 + O_2 -> Cu_2S + 2FeS + SO_2`
`2FeS + 3O_2 -> 2FeO + 2SO_2`
`2Cu_2S + 3O_2 -> 2Cu_2O + 2SO_2`
(ii) `text(Smelting)` : `Cu_2O + FeS -> Cu_2S + FeO`
`FeO + SiO_2 -> FeSiO_3`
(iii) `text(Bessemerisation)` : `2FeS + 3O_2 -> 2FeO + 2SO_2`
`FeO + SiO_2 -> FeSiO_3`
`2Cu_2S + 3O_2 -> 2Cu_2O + 2SO_2`
`Cu_2S + 2Cu_2O -> 6Cu + SO_2` (self reduction)
(iv) `text(Poling)` : Molten `Cu` is stirred with poles of green wood to reduce any copper oxide in Copper.
(v) `text(Electrolytic refining)` : Anode - impure `Cu`; cathode - pure `Cu`; electrolyte `CuSO_4 + H_2SO_4`.
`text(Note)` : Low gread copper can be extracted by hydrometallurgical process also.