The Process: Industrial Applications

The process of wet extrusion, also known as Low Pressure Extrusion, is widely used to convert a variety of industrial chemicals from fine, dusty powders to free flowing, non-dusty granules of uniform shape and size. Extrusion and spheronization can overcome many problems encountered when converting powders to granules, including: low active level, thermally degraded products, low yield of granules within desired size range, too much dust (or high level of fines), unacceptable particle shape or surface texture, and insufficient bulk/particle density (low crush strength).

The wet extrusion process can be batch or continuous operation and consists of the following steps:

Step 1: Powder Feeding

Pre-mixed dry powders are fed into a continuous mixer by a specially designed Mass Flow Feeder.

Step 2: Mixing

A liquid addition system sprays or drips water or organic solvent onto the dry powder which is mixed to form a homogeneous wet mass suitable for wet extrusion. The specially designed mixer continuously conveys the wet mass into the extruder.

Step 3: Extrusion

The Extruder transforms the homogeneous wet mass to produce well-formed cylindrical extrudates of a controlled diameter. The extrudates break off by their own weight and are collected for the next processing step. Depending on the desired end product, the wet extrudates will either be spheronized or dried.

Step 4: Spheronization

The wet extrudates are charged to a spheronizer where a gridded, fast spinning disk (friction plate), breaks them into smaller particles and rounds them to form spheres.


Extrudates	After 5 seconds	After 15 seconds	After 120 seconds

Step 5: Drying

The wet extrudates (or spheres) exiting the extruder (or spheronizer) are charged to the inlet of a Continuously Vibrating Fluid Bed Dryer. The dried granules (or spheres) are then discharged to sieving and / or packaging.