Probability based models for the power draw and energy spectra of a tumbling mill
Doctoral Thesis
2013
Permanent link to this Item
Authors
Supervisors
Journal Title
Link to Journal
Journal ISSN
Volume Title
Publisher
Publisher
University of Cape Town
Department
License
Series
Abstract
Positron Emission Particle Tracking (PEPT) and the Discrete Element Method (DEM) are used to develop probability based models for the power draw and collision energy spectra of a tumbling mill. Experiments are conducted using dry spherical glass bead charge in a laboratory scale tumbling mill, which is mounted with a torque transducer and tachometer to measure mill power. Particle tracking information from PEPT is used to reconstruct the motion of glass beads and infer the overall charge behaviour, while DEM is employed to simulate particle motion and interaction, with collision mechanics calculated using the Hertz-Mindlin contact model. For both sets of data, the product of torque and average angular velocities in discrete cells are accumulated to obtain mill power. This method is found to be within statistical agreement with measured power for all tests. The information from both techniques is then used to develop a model for the power draw as a function of particle size, mill speed and volumetric filling. Predictions of the model match well with measured and calculated values. Based on frequency distributions of collision energies from DEM, a model for the energy spectra of each particle size per steady state mill revolution is developed. This model is found to predict collision frequencies within close agreement with DEM simulation data and follows trends consistent with existing work on tumbling mill modelling.
Description
Includes abstract.
Includes bibliographical references.
Keywords
Reference:
Bbosa, L. 2013. Probability based models for the power draw and energy spectra of a tumbling mill. University of Cape Town.