Abstract
Bulk handling of powders and granular solids is common in many industries and often gives rise to handling difficulties especially when the material exhibits complex cohesive behavior. In this study the effect of moisture on the level of cohesion, and thus handleability, of iron ore fines is investigated. The compression and flow function of the iron ore fines was established form a semi-automated uniaxial tester – the Edinburgh Powder Tester (EPT). The confined compression behavior of the material in terms of stress, strain and density can be measured as well as the unconfined shear behavior. The cohesive strength is determined from unconfined compressions tests following confined consolidation to a range of consolidation stresses.
Discrete Element Method simulations of the experiment were carried out using a recently developed DEM contact model for cohesive solids, an Elasto-Plastic Adhesive model. This particle contact model uses hysteretic non-linear loading and unloading paths and an adhesion parameter which is a function of the maximum contact overlap. The model parameters for the simulations are phenomenologically based to reproduce the key bulk characteristics exhibited by the solid (Morrissey 2013; Morrissey et al. 2013).
The experimental data from the EPT provides a comprehensive set of results for the material behavior. As well as the shear strength, the detailed stress-strain behavior of the material for both confined and unconfined compression is measured. The DEM predictions were compared with the experimental observations and an excellent agreement was found between the DEM simulated flow functions and the experimentally observed flow functions of the cohesive iron ore fines. The strong correlation between the DEM and experimental results demonstrates the potential of DEM simulations to be used in assessing bulk handling situations.
John P. Morrissey
Research Scientist in Granular Mechanics
My research interests include particulate mechanics, the Discrete Element Method (DEM) and other numerical simulation tools. I’m also interested in all things data and how to extract meaningful information from it.