The most important physical method:
Optical: Separation based on optical and other properties. This is often
called sorting, which used to be done by hand.
Concentration: Separation based on differences in density between the
Froth flotation: Separation utilising the different surface properties of
the minerals. This is one of the most important method of
concentration, and is effected by the attachment of the mineral particles
to air bubble within within the agitated pulp. By adjusting the climate
of the pulp by various reagents, it is possible to make the valuable
minerals air-vid (aerophilic) and the gangue minerals water-avid
This results in separation by transfer of the valuable minerals to air
bubbles which form the froth floating on the surface of the pulp.
Magnetic properties: separation dependent on magnetic properties. Low
intensity magnetic separators can be used to concentrate ferromagnetic minerals
such as magnetite (Fe3O4), while high-intensity separators are used to separate
paramagnetic minerals from their gangue.
It is used to remove paramagnetic wolframine ((Fe, Mn) WO4)) and hematite
(Fe203) from tin ores that has considerable application in the area of nonmetallic minerals.
High-tension separation: separation dependent on electrical conductivities
properties. It can be used to separate conducting minerals from non conducting
minerals. The minerals must be completely dry and the humidity of the
surrounding air must be regulated, since most of the electron movement in
dielectrics takes place on the surface.
Ore which are very difficult to treat (refractory), due to fine dissemination of the
minerals are therefore required the combination of one of two of the above
techniques. Example: Zinc-lead-silver (it has problem of fine grained texture) –
This involves Labour cost, supplies, energy e.t.c. for the...