Abstract
Aiming at predicting what happens in reality inside mills, the contact parameters of iron ore particles for discrete element method (DEM) simulations should be determined accurately. To allow the irregular shape to be accurately determined, the sphere clump method was employed in modelling the particle shape. The inter-particle contact parameters were systematically altered whilst the contact parameters between the particle and wall were arbitrarily assumed, in order to purely assess its impact on the angle of repose for the mono-sized iron ore particles. Results show that varying the restitution coefficient over the range considered does not lead to any obvious difference in the angle of repose, but the angle of repose has strong sensitivity to the rolling/static friction coefficient. The impacts of the rolling/static friction coefficient on the angle of repose are interrelated, and increasing the inter-particle rolling/static friction coefficient can evidently increase the angle of repose. However, the impact of the static friction coefficient is more profound than that of the rolling friction coefficient. Finally, a predictive equation is established and a very close agreement between the predicted and simulated angle of repose is attained. This predictive equation can enormously shorten the inter-particle contact parameters calibration time that can help in the implementation of DEM simulations.
Highlights
With the rapid development of computing power and advanced contact algorithm, the discrete element method (DEM) has been extensively applied as a leading tool to describe diverse issues in granular processes, including many industrial applications, such as mining, chemical, cement, and agricultural industries, tumbling mills [1,2,3,4,5,6,7,8,9,10,11,12]
DEM simulations hitherto have been demonstrated their extremely desirability to predict what happens in reality, as well as the quantitatively accurate information representation inside the mills, while the accuracy of outcomes for DEM simulations depends highly on the input parameters [13,14,15,16,17,18], including parameters such as contact parameters, mechanical properties, and particle shape
The second approach was to set a series of arbitrary input parameters in DEM simulations until the results were in very close agreement to the experimental results, namely, sand-pile calibrations [29,30,31]
Summary
With the rapid development of computing power and advanced contact algorithm, the discrete element method (DEM) has been extensively applied as a leading tool to describe diverse issues in granular processes, including many industrial applications, such as mining, chemical, cement, and agricultural industries, tumbling mills [1,2,3,4,5,6,7,8,9,10,11,12]. The contact parameters between particles and the wall were commonly determined with various experimental setups in the first place, and the repeated sand-pile test was subsequently employed in calibrating the inter-particle contact parameters, in order to reduce the number of calibrations. Many investigators employed the simple spherical shape in the majority of DEM simulations to achieve a reasonable simulation time, but the shortcomings of unrealistic simplifications and assumptions are clear Such simplified models are an unrealistic measure on both the physical properties and contact parameters, as well as a poor particle representation on the packing characteristics. As well as the computational effort, the determination of the contact parameters should be studied quantitatively for determining which parameter has the greatest impact on the angle of repose. A predictive equation was formed, which will provide the basic data for the DEM simulations of tumbling mills
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