Theory:

There are four types of ore separation based on the nature of the ore.
  • Hydraulic (Gravity Separation) method.
  • Magnetic separation method.
  • Froth floatation.
  • Chemical method or Leaching.
The different types of ores of metals are given in the below table:
  
Oxide Ores
Carbonate Ores
Halide Ores
Sulphide Ores
Bauxite (\(Al_2O_3.2H_2O\))Marble (\(CaCO_3\))Cryolite (\(Na_3AlF_6\))Galena (\(PbS\))
Cuprite (\(Cu_2O\))Magnesite (\(MgCO_3\))Fluorspar (\(CaF_2\))Iron pyrite (\(FeS_2\))
Haematite (\(Fe_2O_3\))Siderite (\(FeCO_3\))Rocksalt (\(NaCl\))Zinc blende (\(ZnS\))
 
The concentration of the crushed ore is done mainly by the following methods:
  
1. Hydraulic (Gravity Separation) method:
  
Principle:
The difference in the density or specific gravity of the ore and gangue is the main principle behind this method.
Oxide ores are purified by this method.
Example:
Haematite \(Fe_2O_3\) the iron ore.
Important!
Note: Hydraulic method is used when the ore is heavier than the impurity.
Method:
 
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Hydraulic washing
 
The ore is poured onto a sloping, vibrating corrugated table with grooves, then washed down with a stream of water.
 
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Industrial ore washing process

The denser ore particles settle in the grooves, while the lighter gangue particles are washed away by water.