Sieving

Sieving is a simple and convenient technique of separating particles of different sizes. A small sieve such as that used for sifting flour has very small holes which allow only very fine flour particles to pass through. The coarse particles are retained in the sieve or are broken up by grinding against the screen windows. Depending upon the types of particles to be separated, sieves with different types of holes are used. It is also used to separate stones from sand.