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Principle of wet granulator and precautions in granulation

1.Wet granulation : high-speed granulation

principle

High-speed mixing granulation generally involves two steps of mixing (in some cases, some materials need to be pre-mixed) and granulation. When granulating, the adhesive is also sprayed down from the top of the material. The liquid in the adhesive wets the surface of the drug powder to cause adhesion between the particles, and then the powder agglomerates under the action of the liquid bridging formed by the binder and the applied mechanical force to form particles of a certain shape and size. Common problems with high-speed mixing and pulling are:

 

1.1  material agglomeration is serious, excessive granulation

Excessive granulation can occur when the binder is added too quickly, excessively or if the granulation time is too long. Therefore, care should be taken to prevent excessive pulling during granulation. 

Methods for controlling excessive granulation are: controlling granulation time, detecting current, detecting torque, and the like. However, these methods are not suitable for all materials, and sometimes they are not very effective. Therefore, when determining the formulation process for wet-drawing, the tolerance range should be investigated to facilitate product reproduction or amplification. 

 

1.2 Loose particles and more fine powder

(1) When ethanol is contained in the binder and the amount of ethanol is high, the pellets are looser.

(2) The amount of binder added is small, or the granulation time is short, and some materials do not form granules, so that the granules will have more fine powder.

(3) The type of binder is not properly selected and a solid bridge cannot be formed between the powders. It is recommended to replace the adhesive with a higher viscosity. 

 

1.3 There are large over-wetting particles in the material during the granulation process, but other materials are still in powder form.

(1) The stirring speed and the rotation speed of the granulating knife are low, and the adhesive cannot be quickly dispersed.

(2) The material has materials that are easily soluble in the binder solution. It is recommended to replace the binder solvent.

(3) The material has a viscosity which is relatively high after water contact, and ethanol or a part of ethanol solution may be used as the binder.

 

——Finished and made by Yangzhou Nuoya Machinery Co.Ltd——

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Post time: Sep-11-2019