Agglomeration

In process engineering, agglomeration generally means the enlargement of a particle, and is also referred to as grain enlargement or granulation. A prerequisite for the formation of agglomerates is the existence of many contact points between the primary particles and the adhesive forces at these contact points. In principle, all solid substances can be agglomerated if these are fine enough. Agglomeration is carried out either with or without a binding agent, whereby the use of binding agents predominates.

The aim of agglomeration is to simplify the storage of a substance. In addition, the material properties, such as pourability, miscibility and dust formation are to be improved.

In agglomeration, a distinction is made between various techniques, such as pelleting, flocculation or sintering.  In pelleting, for example, granulates with high bulk density are made from plastic waste. With the aid of friction, the granules are plasticized at temperatures below the melting point. In the case of sintering, the heating of fine-grained, solid substances enables the molecules on the melting particle surfaces to bond with one another. Flocculation is an important process in the filtration of substances, because it ensures that solid particles in liquid are joined together to form larger particles.

Applications

Agglomeration should not occur in most products based on emulsions, as a positive feature of an emulsion is the smallest possible particles and agglomeration is a precursor of phase separation. In order to counteract agglomeration and to reduce the size of particles in liquid or highly viscose products, use is usually made of the Homogenisation process to ensure that a stable emulsion is produced.

A desired agglomeration process, on the other hand, is the removal of lactose from milk. Agglomeration is mostly carried out on suspensions, in order to separate desired or undesired particles.

Details

In the case of agglomeration, it is most important that the individual solids are brought into contact with each other and can thereby be joined. Subsequently, any influence of forces on the agglomerate must be avoided, in order to avoid the destruction of the agglomerate.