Answer:  

Dr. Yoshida Hideto, who is actually studying the separation of powder, kindly answered the question above:
 
  
In the case of the sugar and salt mixture, both sugar and salt have their own particle size distributions. Suppose that there is a big difference between the particle size of sugar and the particle size of salt, we can separate them by centrifugal force. In other words, when we put the mixture in the centrifugal force field, large-size particles become gathered on the wall, whereas, small-size particles are concentrated at the center of rotation. “Cyclone” is the major separation instrument.
 
Another separation method is to classify the particle size using a sieve. Small-size particles can go through a sieve, but large-size particles cannot go through, and remain on the sieve. 
 
It is also possible to separate particles using magnetic force or electrostatic force. In the case of the mixture of sand and iron powder, we can easily separate iron powder from the mixture using magnetic force.
 
 
Acknowledgement
We would like to thank Dr. Yoshida Hideto for his kind answer.
 
 

This article is translated by Chemistryquestion.com from the original article in Chemistryquestion.jp.  Please let us know if you find any errors.