Market Survey on Copper - Indian Bureau of Mines

Beneficiation of copper ore depends upon chemical, physical and mineralogical
characteristics of the constituent minerals. Copper sulphide minerals are normally
beneficiated by froth flotation.
3.2.1 Processing of Copper Ores
A) Comminution
B) Concentration
C) Dewatering
A) Comminution
Removal of gangue minerals from the copper minerals requires that first
the ore should be comminuted (crushed and ground) to a size fine enough to
ensure fair liberation of gangue minerals from copper minerals and other
associated valuable sulphide minerals. Comminution is performed in two stages
i.e. crushing and grinding.
(i) Crushing
Copper ores extracted from the mines are generally in the form of lumps
of size up to 1000 mm. The feed to grinding mills is in the range of 10-20 mm
size. Crushing of 1000 mm lumps to 10-20 mm size involves a reduction ratio
of 50- 100 in multi-stage crushing. Depending upon the nature of the ore and
capacity of the plant, jaw or gyratory crushers are employed for first stage of
crushing (primary crushing). Clayey and plastic materials are crushed by jaw
crushers whereas gyratory crushing is adopted for hard and abrasive ores.
Gyratory crushers yield more cubical product from slabby lumps. The capacity
of gyratory crusher is more than double the capacity of an equivalent size jaw
crusher, that is why gyratory crusher are preferred for large capacity plants.
crusher is a primary crusher used in copper industries. In designing, crushing
circuit for hard ore, it is advisable to over-design the primary crushing plant to
provide stockpiles of coarse product to ensure steady feed to secondary
crushers. The size of the product from the primary crusher is in the range of
100-200 mm.
The second stage of crushing (secondary crushing) is usually carried out
employing cone crushers and roll crushers for hard and soft ores, respectively.
The cone crushers with mantle of diameter 1300 mm to 2150 mm are in
operation in many plants. The secondary crushers discharge at 20-25 mm size.
Third stage of crushing (tertiary crushing) is employed to obtain a product in the
size range of 3-15 mm. Usually, short (mantle diameter up to 2 m) are
employed in closed circuit to ensure that crushed product is of the desired size.
The reduction ratio for primary, secondary and tertiary crushing must not
increase beyond 8, 6-8 and 4-6 respectively.
(ii) Grinding
Fine grinding is usually done in rod mills in open circuit followed by
ball mills in closed circuit with classifiers, cyclones, etc. In recent years, there
is a trend to use Autogenous mills.
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