Starting materials: • Watery solutions • emulsions • suspensions • waxes • meltable raw materials (in the form of melts, melt emulsions and melt suspensions)

Spray granulation is a process used in fluid bed technology that enables the conversion of liquid substances into free-flowing granules. In the fluid bed granulator, the liquid is finely atomised and sprayed onto a carrier material, whereby solid granules are gradually formed.

Fluid bed granulation for customised product properties

Spray granulation allows the targeted adjustment of granule size and other important properties such as porosity, density, and surface texture. This enables us at inprotec to respond perfectly to your individual requirements and supply you with customised granules for your application.


Before the actual spray granulation begins, we can mix, disperse, emulgate, heat, cool and, if necessary, neutralise or carry out simple chemical transformation reactions on either solid or liquid starting materials in our fluidized bed plants or additional equipment. Then, raw materials and initial products for the granulation are transformed into a liquid and therefore atomizable form.

  1. fluidized bed
  2. spray solution
  3. granulate discharge
  4. inlet air
  5. exhaust air
  6. sifter air
  7. sifter outlet

The fluidized bed granulation principle is shown in the schematic diagram above. In this process, the liquid (2) is atomized into ultra-fine droplets (diameter: 20–50 µm) by several two-material nozzles. The droplets enter the air stream (4) of the fluidized bed unit and dry instantaneously due to the direct and intensive heat exchange. The moist air is discharged (5) through the top of the unit. The fluidized bed drying initially produces minute particles – the so-called germs. These are held in suspension in the fluidized bed (fluidization, 1). Continuously atomized droplets adhere to their surface and dry so that a so-called onion structure or snowball structure builds up. The particles are discharged from the process (3) and; at the same time, are classified in a sifter (6) so that coarse particles are discharged (7) and fine particles are fed back into the process chamber to allow their continuous build-up to a certain particle size. The classifying discharge allows particles to be removed from the reactor flexibly, continuously and without interrupting the drying process. Particles sizes between 200 and 5,000 µm can be set freely. The fluidized bed spray granulation therefore unites the drying with a precisely definable particle formation.

In the spray granulation, the particles are enveloped with several layers of the spray material so that the process is also known as build-up granulation. If several materials are sprayed at the same time, the so-called co-granulation is performed. Generally, the starting materials and the process conditions in the spray granulation processes can be configured in such a way that various particle morphologies with different properties and characteristics can result. Thanks to their often round shape, the granulates are ideal for subsequent coating.

Advantages of spray granulation:

  • Dust-free processing: Granulation converts dusty powders into easy-to-handle granules.
  • Improved dosing: The free-flowing granules can be dosed easily and precisely.
  • Optimised solubility: The porous surface of the spray-granulated particles ensures faster and more complete dissolution.
  • Lower hygroscopicity: The granules absorb less moisture from the ambient air than powders.
  • Ideal for further processing: Spray granules are ideal for tableting, capsule filling, and other processing steps.