Extrusion / Spheronization
The traditional solution for manufacturing pellets
Agglomeration through extrusion and spheronization is one of the oldest techniques for manufacturing pellets.
The process consists of four process steps: Moistening the powder mixture, forming cylinder-shaped agglomerate through extrusion, breaking and rounding the extrudate to round pellets through spheronization, and drying the finished product.
The dry, mixed, powdery active substances are kneaded into a dough with a liquid. This dough then pressed through an extruder. The diameter of the openings in the extrusion plate or extrusion basket determines the strength of the elongated extrusion threads that result. For technical reasons, the resulting pellets are larger than 600 micrometers.
The ratio of liquid to solid material together with the size of the extruder holes significantly determines the quality of the extrudates. The final drying ensures the pellet hardness.
Even if the ball-shaped extrudate is imperfect, the evenness of the surface still creates good conditions for subsequent coating. For many pharmaceutical applications, extruded pellets are achieved in suitable quality if a sufficient portion of microcrystalline cellulose is added.
In the pharmaceutical industry, pellets of medium particle sizes from 600 to 2,000 micrometers are used for most applications. In other industries, the size of the pellets can be several centimeters. Just the way you need it.