Extraction of Copper
The main ores of copper are:
(a) Copper pyrites (CuFeS2)
(b) Cuprites (Cu2O)
(c) Copper (i)Sulphide known as Copper glance (Cu2S)
Copper pyrite is mostly used to extract Copper (chief ore).
Extraction of copper from copper pyrite involves three stages
1. Concentration of the ore by removing earth impurities
2. Roasting of the ore and reduction
3. Purification(refining) of impure copper
Concentration of the copper ore
Copper pyrite is first crushed to a powder and then mixed with water and oil. Air is then blown
through the mixture and heavier impurities sink to the bottom of the tank. The float on the
surface containing the concentrated ore is separated off
Roasting of the ore
The copper concentrate is then roasted in air in a furnace producing copper(i)sulphide (Cu2S),
iron(ii) oxide(FeO) and Sulphur dioxide gas(SO2)
2CuFeS2(s) +4O2(g) Cu2S(l) + 2FeO(l) + 3SO2(g)
The Sulphur dioxide gas escapes from the bottom of the furnace
Iron(ii) oxide is removed by heating it in the absence of air with silica(SiO2) which is added to it
in the furnaces, iron (ii) silicate is formed as a slag which floats on top of the molten copper(i)
sulphide
FeO(l) + SiO2 FeSiO3(s)
The copper(i) sulphide is then finally reduced to the copper metal by heating in a controlled
amount of air
The impure copper is called blistered copper because of the blistered appearance of the copper
surfaces on cooling caused by the escaping gases
Cu2S(l) + O2(g) Cu(s) + SO2(g)
Purification of Impure Copper
The impure copper is purified by electrolysis
Impure copper bars form the anode and the pure copper metal bars form the cathode
The electrolyte (a substance which can allow electricity to flow and be decomposed by it) is a
solution of CuSO4
The anode dissolves because its atoms give up electrons to form Copper ions according to the
equation
Cu Cu2+ + 2e.
The Cathode becomes big because the Copper ions that have come from the impure anode grab
the electrons and become Copper atoms. These atoms stick onto the Cathode hence increasing in
size
Cu2+ + 2e Cu
+ _
Impure copper (anode) Copper(ll)ions Pure copper (cathode)
ions
Dissolves away
Copper (II) sulphate solution
Gold and Silver as
Impurities(sludge)
Properties of Copper
(i) It is a reddish brown metal
(iii) It has a very high melting point and boiling point.
(iv) It has a very high density
(v) It is a good conductor of heat and electricity
(vi) It is ductile and malleable
(vii) It is not easily attacked by air and water.
Uses of copper
1. it is used in making electric cables because it is a good conductor of electricity
2. it is used in making alloys e.g. bronze and brass
3. it is used in making coils
4. it is used in making ornaments in jewelry industries e.g. coins, necklaces and rings
5. it is used in making cooking utensils and boilers since it is a good conductor of heat
By Mr Phiri. P
