Mixture separation

The components of the mixtures may be separated. There are a few techniques to accomplish this separation. The type of separation depends on the type of mixture.

Some of the separation methods are: picking, levitation, dissolution or flotation, sieving, magnetic separation, fractional dissolution, decantation and sedimentation, centrifugation, filtration, evaporation, simple and fractional distillation and fractional fusion.

Solids separation

To separate solids we can use the following methods.


It basically consists in collecting with the hands or tweezers one of the components of the mixture. Example: Separate beans from impurities before cooking them.


Separates denser from less dense substances using running water. Example: The process used by prospectors to separate gold (denser) from sand (less dense).

Dissolution or flocculation

It consists of dissolving the mixture in solvent with intermediate density between the densities of the components of the mixtures.

Example: sawdust + sand
Add water to the mixture. The sand lies at the bottom and sawdust floats in the water.


Separates larger solids from smaller solids or suspended solids in liquids.

Examples: Masons use this technique to separate finer sand from pebbles; to separate the pulp of a fruit from its seeds, such as passion fruit. This process is also called sieving.

Magnetic separation

Used when one of the components of the mixture is a magnetic material. With a magnet or electromagnet, the material is removed. Example: iron filings + sulfur; sand + iron


Used to separate two solid components with different densities. An air blast is applied to the mixture.

Example: to separate roasted peanuts from their already loose shell; rice + straw.

Fractional dissolution

It consists of separating two solid components using a liquid that dissolves only one of them.

Example: salt + sand
Dissolve the salt in water. The sand does not dissolve in water. The mixture can be filtered by separating the sand, which is trapped in the saltwater filter. Water can be evaporated by separating water from salt.