Principles of Extraction or Metallurgical Operations:- The whole process of obtaining a pure metal from ores is known as metallurgy. The extraction of pure metal from its ores involves several physical and chemical methods. The suitability of a method depends upon the nature of ore, the properties of metal and the local conditions. Therefore it is not possible to chalk out a universal procedure for the extraction of all metals from their ores. However, some general operations made during extraction of metals from their ores are cited below.
1)   Crushing of ores: - larger pieces of ores obtained from earth crust are broken up in to smaller pieces. This process is known as crushing of ore.
2)   Dressing or concentration of ores: - presence of earth matter, rockmatter, sand, lime stone, mica etc. in ores is known as Gangue or Matrix, removal of these impurities from ores is called as dressing or concentration. Following methods are commonly used for dressing up or ores depending upon the nature of ore.
a)   Handpicking
b)   Levigation or gravity separation or hydraulic washing method
c)   Magnetic conc. Method
d)   Forth floatation process
e)   Activators and depressants