Metallurgy is the study of techniques and procedures which are used to extract metals from earth crust. copper is extracted from its pyrite ores.

1. METALLURGY OF COPPER
XII CHEMISTRY CHAPTER 5
SIDRA JAVED

2. IMPORTANT ORES OF COPPER
1. Copper pyrite or chalcopyrite CuFeS2
2. Chalcocite or copper glance Cu2S
3. Malachite green [CuCO3.Cu(OH)2]
4. Azurite blue [2CuCO3.Cu(OH)2]
5. Bornite or Peacock ore [3Cu2S.Fe2S3]
6. Cuprite Cu2O

3. EXTRACTION OF COPPER
• Copper is mainly extracted
from its sulfide ores by
smelting.
• Following steps are
involved in the extraction
of copper:

4. CONCENTRATION
• Finely crushed ore is concentrated by FROTH FLOATATION PROCESS.
• Crushed ore is suspended in water containing a little amount of pine oil.
• A blast of air is passed through the suspension.
• The particles mix with the oil and float as a froth which is skimmed.
• The gangue sinks to the bottom.

5. FROTH
FLOATATION
PROCESS

6. ROASTING
• The concentrated ore is then roasted in the furnace in the presence of oxygen.
During roasting sulfur, arsenic, antimony are converted into oxides and are
removed.
2CuFeS2 + O2  Cu2S + 2FeS + SO2
S + O2  SO2
4As + 3O2  As2O3
4Sb + 3O2  2Sb2O3
• Cuprous sulfide and ferrous sulfide are further oxidized into their oxides.
2Cu2S + 3O2  2Cu2O + 2SO2
2FeS + 3O2  2FeO + 2SO2

7. ROASTING

8. SMELTING
• Roasted ore is then mixed with coke and sand and is fed into a blast furnace.
Hot air converts FeO to iron silicate (FeSiO3).
FeO + SiO2  FeSiO3 (Slag)
Cu2O + FeS  Cu2S + FeO
• Slag floats over the molten matte of copper.

9. BESSEMERIZATION
• Matte contains Cu2S and some unreacted FeO along with silica as impurity.
• It is converted into copper in a special furnace which is known as "Bessemer
converter".
• When air is blown through the matte, the following reactions take place:
2Cu2S + 3O2  2Cu2O + 2SO2
2Cu2O + Cu2S  6Cu + SO2
2FeS + 3O2  2FeO + 2SO2
FeO + SiO2  FeSiO3
• The copper so obtained is called "Blister copper" because, as it solidifies, SO2 hidden
in it escapes out producing blister on its surface

10. BESSEMER
CONVERTER

11. IMPURITIES IN
BLISTER COPPER
• Blister copper is 99% pure.
It contains impurities
mainly Fe, As, Zn, Pb, Ag
and Au.
• These impurities adversely
affect the electrical as well
as mechanical properties
of copper.

12. REFINING OF BLISTER COPPER
• Blister copper is refined by electrolysis.
• Blocks of blister copper are used as anodes and thin sheets of pure copper act as
cathodes.
• The cathode plates are coated with graphite in order to remove depositing copper.
• The electrolyte is copper sulfate (CuSO4) mixed with a little amount of H2SO4 to
increase the electrical conductivity.
• Optimum potential difference is 1.3 volt for this electrolytic process.

13. ELECTROLYSIS
• During electrolysis, pure copper is deposited on the cathode plates and
impurities which are soluble and fall to the bottom of the cell as anode mud
or sludge.
At anode: Cu (Blister Copper)  Cu+2 + 2e-
At Cathode: Cu+2 + 2e-  Cu (Pure Copper)
• This electrically refined copper is 100% pure.

14. ELECTROLYTIC
REFINING

15. PURE COPPER

17. END OF LESSON
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