Numerical Simulation of Particle Dynamics in a Spiral Jet Mill via Coupled CFD-DEM.

Satyajeet Bhonsale,Lewis Scott,Mojtaba Ghadiri,Jan Van Impe

doi:10.3390/pharmaceutics13070937

Satyajeet Bhonsale, Lewis Scott + Show 2 more

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https://doi.org/10.3390/pharmaceutics13070937

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Journal: Pharmaceutics	Publication Date: Jun 23, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: KU Leuven, University of Leeds

Abstract

Spiral jet mills are ubiquitous in the pharmaceutical industry. Breakage and classification in spiral jet mills occur due to complex interactions between the fluid and the solid phases. The study of these interactions requires the use of computational fluid dynamics (CFD) for the fluid phase coupled with discrete element models (DEM) for the particle phase. In this study, we investigate particle dynamics in a 50-mm spiral jet mill through coupled CFD-DEM simulations. The simulations showed that the fluid was significantly decelerated by the presence of the particles in the milling chamber. Furthermore, we study the particle dynamics and collision statistics at two different operating conditions and three different particle loadings. As expected, the particle velocity was affected by both the particle loading and operating pressure. The particles moved slower at low pressures and high loadings. We also found that particle–particle collisions outnumbered particle–wall collisions.

Highlights

Pharmaceutics 2021, 13, 937. https://Particle size reduction is an important step in the design, development, and processing of active pharmaceutical ingredients (API)
We analysed the effect of particle loading and the operating pressure on the fluid and particle dynamics in a spiral jet mill through coupled computational fluid dynamics (CFD)-discrete element models (DEM) simulations
Three particle loadings and two operating pressures were considered in the study

Summary

Introduction

Pharmaceutics 2021, 13, 937. https://Particle size reduction is an important step in the design, development, and processing of active pharmaceutical ingredients (API). Since spiral jet mills were first patented in the 1930s [3], their design has remained relatively unchanged. Their design consists of a short cylindrical (or elliptical) milling chamber into which high velocity gas is pushed through several nozzles (called the grinding nozzles), which are at an angle to the mill perimeter. The centrifugal forces in the vortex retain the coarse particles within the milling chamber. The centrifugal forces and the radial drag forces acting on the particles in the vortex depend on the particle size (x). As the size decreases due to breakage, centrifugal force (∼ x3 ) reduces faster than the radial drag forces (∼ x2 )

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