Particle methods for modelling in mineral processing

Abstract

The Discrete Element Method (DEM) is a computational method that is well suited for modelling flows of particulate materials in mineral processing. Smoothed Particle Hydrodynamics is a particle-based method for modelling fluid flows and is highly compatible with DEM allowing relatively easy coupling of particulate and liquid phases. In this article, we will explore recent modelling of some important unit processes used in mineral applications using these particle-based methods. Specifically, models of a particle and slurry motion are presented for a full three-dimensional semi-autogenous mill at several different scales. These are used to explore particulate motion in the charge, slurry motion within the charge, discharge through the grate and pulp lifter system and the varied breakage processes occurring within these machines. The importance of rock shape and its evolution on the balance of breakage mechanisms within the mills are discussed. Finally, an example of application of DEM to predict particle behaviour in a twin deck vibrating banana screen is presented.

Keywords:

• discrete element method
• smoothed particle hydrodynamics
• SAG mill
• comminution
• breakage
• slurry transport
• separation

Acknowledgements

This work was supported by the Centre for Sustainable Resource Processing, which is established and supported under the Australian Government's Cooperative Research Centres Programme. The authors thank Dr. Matt Sinnott for his contribution to visualisation and geometry construction, Dr. Mahesh Prakash for his work on the slurry discharge and collaborators at the University of Cape Town and the University of Kwa-Zulu Natal.