Abstract

â??Effect of Bed-height and Number of Blade Passes on Powder Mixing Performance and Derivation of a Mathematical Relationshipâ?
Siraj, M. S.1,2*, Khinast, G. J.1,3
1. Graz University of Technology, Graz, Austria.
2. *Currently working at Pakistan Institute of Engineering & Applied Science (PIEAS), Nilore, Islamabad, Pakistan.
3. Research Center Pharmaceutical Engineering GmbH, Graz, Austria.
Solid particle mixing is an important industrial phenomenon and is crucial in chemical and pharmaceutical industries. In the latter case, it becomes critically important as it is directly linked to the drugs performance as the active pharmaceutical ingredient has to be mixed properly with the excipients in a drug in order to avoid blanks or super-potent pills. This leads to strict drug regulatory laws to be followed by the industry. These regulatory requirements and the Quality by Design (QbD) initiative in the process industry require a deeper understanding of the mixing phenomena on a basic level and the mixers being used for this purpose, which are in many cases convective mixers.
Some of the effects, e.g., blade angle and blade shape have already been studied [1-3]. In this work, however, a detailed investigation was done using a simple geometry [1,2] to study the effects of bed-height and number of blade passes on the powder mixing performance and more importantly with an objective to derive a mathematical relationship between these. Number of particles in this study were significantly higher as well as the length of the box than in our previous study [1]. Additionally, blade force and variation of inter-particle forces were also studied with the change in bed-height and number of blade passes. A mathematical relationship was also derived successfully and will be presented.

References

[1] M.S. Siraj, S. Radl, B.J. Glasser, J.G. Khinast, Effect of Blade Angle and Particle Size on Powder
Mixing Performance in a Rectangular Box. Powder Technology 211 (2011) 100-113.
[2] M.S. Siraj, J.G. Khinast, Effects of Blade Shape and Angle on Solid Particle Mixing Using 2D and 3D Discrete Element Simulations, 544b (presented on Nov 10, 2010), 2010 AIChE Annual Meeting, Nov
7-12, 2010, Salt Lake City (UT) USA.
[3] G.R. Chandratilleke, A.B. Yu, R.L. Stewart, J. Bridgwater, Effects of blade-rake angle and gap on particle mixing in a cylindrical mixer, Powder Technology 193 (2009) 303â??311.