Granulation with Hosokawa: Wet vs. Dry

Hosokawa Micron offers granulators that work by two different methods.  Agglomeration by pressing the particles together using mechanical force, dry granulation with the Kompacktor, and agglomeration using a binder, wet granulation with the Flex O Mix.  This short article will highlight the way both technologies work.

Granulation, sometimes known as agglomeration, is the process of taking a bulk solid and turning it into granules.  This process may improve the flowability, change the mechanical properties, reduce dust, or ease the handling of the powder.  It is used across all industries, from pharmaceutical and food applications to chemical and mineral applications.

Hosokawa’s dry granulation technology is a two-step, continuous process that combines a roller compactor, such as the Alpine Kompacktor or Pharmapaktor, with a low-energy size reduction mill.  The bulk solid is force-fed into the compaction zone in the roller compactor, creating small briquettes, flakes, or a ribbon.  This compacted material is then milled by one or more “flake crushers” in order to achieve the desired granule size.  In applications that require reduced fines or dust, a sieve screener or air classifier can be used to separate the granules and recycle the fines back into the roller compactor.

Hosokawa’s dry granulation process produces uniformly sized and medium to high aspect ratio particles.  They are normally binderless with the potential for high density due to the forced arrangement of small and large particles during compaction.  Additionally, because the compaction process is only mechanical, there is no change to the chemical nature of the material.  This makes the granules well suited to chemical processes as additives or to improve the handling and transportation properties of the material.

The Flex O Mix is Hosokawa’s wet granulation technology and agglomerates powder on a continuous fashion.  It works by rapidly mixing a powder dispersed in air with a sprayed liquid.  The liquid binds the powder into small agglomerates.  The agglomerates then fall into a fluid bed dryer, which gently dries the agglomerates into a hard granule.

The granules formed by the Flex O Mix are formed by the liquid not by pushing the powder(s) together using a strong mechanical force.  This allows for a random shape with high surface area and a porous internal structure.  These allow for a granule that is wettable and soluble, even when made of fine powders that may have trouble wetting when added into a liquid ungranulated.  An example of this is flour, which when added to hot water clumps up and does not fully disperse.  The Flex O Mix will generate granule of the fine powder that is fully dispersible. Some examples of situations where this is a valuable effect are powder detergents, soup mixes, and some powder pesticides.

Both wet and dry granulation have their unique applications and benefits to your process.  Please contact your local Hosokawa representative or our home office to discuss which is best for you.