Mechanism of Size Separation

1. Agitation :

Sieve are agitated by various ways in up - down motion .

1. Vibration : 

sieves are vibrated by mechanical or electrical means in order to allow particle to pass through the sieve .

2. Oscillation :

set of sieves mounted in a frame that oscillates back and forth.

3. Gyration :

sieve are placed on rubber sheet and connected to an flywheel .

2. Centrifugal Force :

A high speed rotor is fixed inside the vertical cylinder sieve , so that on rotation of rotor the particle are thrown outwards by centrifugal force . the Weight of powder retained on each sieve is determined  .

3. Brushing :

powder is passed through sieve by application of brushes in different directions :

i.e. front to back or back to forth or in circular motion .

4. Sedimentation :

particles are separated on the basis of their weight through sedimentation process . Larger particles settle more rapidly while small particle will settle very slowly .

5. Suction and Pressure :

Powder is passed through bags of  defined pore size by suction and lastly pressure is applied to shake bags to collect the powder at bottom .

6. Elutriation :

Particles are separated by fluid flow according to their density . in this case some low density particles will flow in upward direction due to velocity of fluid while , high density particles will flow downwards . Fluid flows opposite to direction of sedimentation . Fluid Velocity play an important role in this technique .