Levitation, sieving and ventilation are methods of separating heterogeneous mixtures.
Through levigating and ventilating it is possible to separate the denser substance from the less dense. In sieving, in turn, the larger grains of substances are separated from the smaller grains.
Density differences determine the use of the levigating process and ventilation. The granulometry (size of the grains), in turn, guarantees the efficiency of the sieving process.
Levitation
The process of levigating is simply passing the mixture through water.
The goal is to keep the denser substance at the bottom of a container while the less dense substance is washed away.
Levitation is used to separate solid mixtures (solid + solid).
This process is used by miners to separate gold or other precious metals from sand and stones.
Gold, whose density is greater, is extracted from the medium of sand and other particles that accompany it. Material that is not of interest is separated and discarded.
Churragem is the same process, but uses mercury instead of water. However, the method is highly harmful to the environment, since this liquid is a toxic chemical element.
Ventilation
In the ventilation process, the mixture is subjected to a current of air. Thus, the less dense component of the mixture is blown away.
It is a method of separating heterogeneous mixtures between solids.
The main use given to ventilation is in separating grains from their husks or other impurities.
For example, bird breeders use this method to clean the cage. Birds eat seeds and leave their shells scattered. Blowing out the cage is an effective way to clean these debris.
This is the method used in the grain industries to promote the processing of their products.
For a long time it was done manually through sieves in which the grains were placed.
The utensil was handled by someone who blew on its contents and moved it back and forth, up and down. All these movements caused the air current to carry away the impurities and separate the desired content.
Afterwards, fan machines were created and other methods were used.
In addition to density, there are other important aspects, such as dimensions, that must be observed so that the grains present the required commercial standards.
Sieving or Screening
Sieving or sieving consists of sieving substances to separate solid components. The thicker one is retained in the sieve as the finer one passes through the utensil's holes.
In laboratories or industries, sieves, a set of sieves with different meshes, are used to separate different sizes of granulation.
Sieving is used to separate solid substances from other solid substances (solid + solid).
An example of solid substance separation is the sieving of sand by masons in order to separate coarse from fine sand. Fine sand is used in the finishing of a building.
Learn more, read also:
- Separation of Mixtures
- Homogeneous and Heterogeneous Mixtures
- Materials used in the Chemistry laboratory
