Analysis of hold-up and grinding pressure in a spiral jet mill using CFD-DEM

Lewis Scott,Antonia Borissova,Alan Burns,Mojtaba Ghadiri,M.A Aguirre,L.A Pugnaloni,S Luding,R Soto

doi:10.1051/epjconf/202124912004

Abstract

A spiral jet mill was simulated using Discrete Element Method modelling and Computational Fluid Dynamics. The particle behaviour and fluid motion were analysed as a function of hold-up and grinding pressure. Particle collision energy was predicted to be prevalent along the bed surface and in front of the grinding jets, as shown through the collision data recorded. The bed itself affects the fluid flow field, as momentum is transferred to the particles. Increasing the grinding pressure does not result in a proportional increase in the kinetic energy of the particle system, as the high pressure jets begin to penetrate the bed with greater ease. The particle bed moves as ‘plug-flow’, with the layers of the bed closest to chamber wall.

Highlights

Introduction as a parameterMacDonald et al [12] derived a series of analytical equations, which included hold-up, to The spiral jet mill is the equipment of choice in many predict the product cut-size
The under-utilisation of the fluid energy as the jets penetrates through the bed, provides a different reasoning as to why both groups found this result. Both hold-up and pressure effects were investigated in the spiral jet mill using a 4-way coupled CFD-DEM simulation
The amount of material held in the mill indirectly influences the air velocity around the classifier, as kinetic energy is transferred to the particle bed

Summary

Introduction

Introduction as a parameterMacDonald et al [12] derived a series of analytical equations, which included hold-up, to The spiral jet mill is the equipment of choice in many predict the product cut-size. CFD-DEM simulations of the spiral jet mill have in size. During operation of the mill, a particle bed forms two-way coupling, or higher order schemes, one-way around the outer wall of the milling chamber due to the coupling and CFD-only simulations are unable to centrifugal action induced by the grinding jets.

Results

Conclusion