A novel lab-scale screen extruder for studying extrusion-spheronisation

Area of Science:

• Pharmaceutical Engineering
• Materials Science
• Process Engineering

Background:

• Industrial screen extrusion-spheronisation is crucial for pharmaceutical pellet production.
• Replicating industrial conditions in a laboratory setting is challenging.
• Understanding the mechanics of screen extrusion is vital for process optimization.

Purpose of the Study:

• To develop and characterize a novel laboratory roller screen extruder (LRS).
• To investigate the key parameters influencing extrusion performance.
• To evaluate the LRS's capability in assessing formulations for industrial applications.

Main Methods:

• The laboratory roller screen extruder (LRS) was designed to mimic industrial screen extruder geometry and shear rates.
• A cohesive 45 wt% water/microcrystalline cellulose paste was used for commissioning.
• Key operating parameters (gap size, roller speed) were systematically varied.

Main Results:

• Extrudate mass flow rate, screen force, and roller torque were controlled by gap size and roller speed.
• Apparent shear rate, based on blade-screen clearance, emerged as a quantitative scale-up criterion.
• Spheronisation yielded pellets with narrow size distribution and acceptable sphericity.

Conclusions:

• The LRS effectively replicates critical aspects of industrial screen extrusion.
• The developed LRS can be utilized for formulation assessment prior to industrial scale-up.
• The findings support the use of LRS for predicting industrial screen extrusion-spheronisation performance.