Agglomeration in Process Engineering

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 sintering, fine-grained solids are heated below their melting temperature so that the particles bond firmly at their contact points by diffusion. 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 having the smallest possible droplets and agglomeration (flocculation) of the droplets is a precursor of coalescence and phase separation. In order to counteract agglomeration and to reduce the size of particles in liquid or highly viscous products, use is usually made of the Homogenisation process to ensure that a stable emulsion is produced.

Agglomeration is desirable, on the other hand, in the instantising of powders such as milk, coffee or cocoa powder: agglomerated powders produce less dust and wet and dissolve faster. In pharmaceuticals, granulation improves the flowability and compressibility of powder blends for tableting. In suspensions, targeted agglomeration (flocculation) is used to separate solids more easily, for example in water and wastewater treatment.

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.

Would you like to use agglomeration in a targeted way or avoid it in your products? Call us at +49 4203 789492, email info@s-vt.net or use our contact form.

Frequently Asked Questions about agglomeration

What does agglomeration mean?

Agglomeration is the enlargement of particles by clustering, also called grain enlargement or granulation. It requires many contact points and adhesive forces between the primary particles.

Which agglomeration techniques exist?

For example pelleting, flocculation and sintering – with or without binders, binders being predominant.

When is agglomeration desirable?

For example to improve flowability, storability and miscibility, reduce dust, make instant powders (e.g. milk or cocoa powder) dissolve better, granulate powders for tableting or separate solids from suspensions by flocculation.

Why is agglomeration undesirable in emulsions?

It is a precursor to phase separation. Homogenization reduces particle size and stabilizes the emulsion.