The extrusion-spheronization technique is the most traditional and one of the most popular method for producing pellets

The extrusion-spheronization technique is the most traditional and one of the most popular method for producing pellets. This process involves four steps: granulation, extrusion, spheronization, and lastly, drying of the pellets. Granulation is the process of forming into grains or granules and is involved with the preparation of plastic mass. Different types of granulators are used to perform the mixing of the powder blend and the granulation liquid. The 3 most commonly used granulators are planetary mixer, high-shear, and sigma blade mixer. The prepared plastic mass undergoes extrusion at which the pressure is applied to a mass until it flows out through an orifice to produce the extrudates. The extrudate length may vary on a few factors. These factors include the physical characteristics of the materials to be extruded, method of extrusion, and how particles are manipulated after extrusion.
In spheronization, the extruded, cylindrically shaped particles are broken into uniform lengths and are gradually transformed into spherical shapes; this shaping process is due to plastic deformation. As extrudates are first broken into nearly uniform lengths, all three dimensions of agglomerate shape are determined, and spheres with a nearly uniform diameter are produced