Granulation and method of dry granulation
Granulation: It is the scientific method that aims to make particles adhere together to form larger particles called granules, and the size of these particles ranges from 0.2-4.0 mm.
The reasons that require resorting to the granulation process:
1- To prevent separation of ingredients in the powder mixture.
2- To improve the compression properties of the mixture.
3- The granulation process of the particles helps to improve the flow properties of the mixture.
4- The process of granulation of toxic particles helps to reduce the risk of toxic dust during powder handling.
5- Sometimes storing the powder leads to the absorption of a little moisture, which leads to the adhesion of the particles to each other and the formation of a cake. Therefore, to avoid this danger, we use granulation processes that help absorb this moisture without affecting the particles, because the granules bear a higher percentage of moisture than the powder and maintain their ability to flow due to their size.
Dry granulation:
This method is done by collecting the initial powder particles under high pressure, and then subjected to two main operations:
1- The first method: a thick flat disk (1 inch) known as a slug is produced in a heavy duty tablet press (this process is known as slugging). This thick flat disk is then milled to produce a granular material. It is then sieved to separate the required size part. The parts that are not required can be reworked to avoid wastage. Such methods are for medicines that are sensitive to moisture and heat.
2- The second method: It is done by squeezing the powder between two rollers that rotate opposite to each other, and the powder is passed between them to produce a sheet of material. After that, the intermediate products are crushed using a grinding technique to produce a granular material, which is usually sieved to separate the required size and reformulate the unrequired size in the same way or In other ways to avoid wastage, such a method is used for medicines that do not compress well after wet granulation, or for medicines that are sensitive to moisture and heat.