Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations
Tumbling mills are considered to be among the most energy intensive devices in comminution circuits and are designed to achieve size reduction and transport. These functions are influenced by the mill speed, filling and the configuration of the lifter bars attached to the mill shell (height, width,...
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Chemical Engineering
2019
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613266462638080 |
|---|---|
| access_status_str | Open Access |
| author | Uys, Adri Mari |
| author2 | Mainza, Aubrey |
| author_browse | Mainza, Aubrey Uys, Adri Mari |
| author_facet | Mainza, Aubrey Uys, Adri Mari |
| author_sort | Uys, Adri Mari |
| collection | Thesis |
| description | Tumbling mills are considered to be among the most energy intensive devices in comminution circuits and are designed to achieve size reduction and transport. These functions are influenced by the mill speed, filling and the configuration of the lifter bars attached to the mill shell (height, width, face angle, etc.). The lifter height has been shown to influence the charge motion and power draw of the mill. Most of the predictive power models used in industry do not consider lifter heights as a variable. In comminution, Positron Emission Particle Tracking (PEPT) is used to track the charge motion of particles in tumbling mill systems. The data has been used to derive a velocity profile for particle motion between the mill shell and centre of circulation (COC), a region that highlights the distinct particle motion in tumbling mills. In prior work, a laboratory scale mill and PEPT was used to develop a velocity profile model incorporating the lifter height influence on charge motion. The agreement between PEPT and the model predictions was limited to regions closest to the mill shell and the analysis was restricted for conditions where the lifter height was significantly smaller than the particle diameter. The current study aimed to supplement the PEPT results by using the Discrete Element Method (DEM) to simulate the collective effect of individual particle interactions on the charge motion. The DEM results were used to analyse the influence of the lifter height on the charge motion, velocity profile and power draw for an identical tumbling mill system. The PEPT and DEM results agreed on charge motion and power draw changes. The assumption of a constant axial pressure drop (dP/dx) along the cross-section of the mill resulted in deviations between DEM and model predictions of the velocity profile. The calculated axial pressure drop varied non-linearly along the mill radius and followed a similar trend at all operating conditions. The relationship between the velocity profile and axial pressure drop was found to vary non-linearly and followed a similar trend to the stress-strain relation of granular media. It is recommended that further research be conducted on the axial pressure drop and its influence on the velocity profile. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/30087 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:25.185Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2019 |
| publishDateRange | 2019 |
| publishDateSort | 2019 |
| publisher | Department of Chemical Engineering |
| publisherStr | Department of Chemical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/30087 The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations Uys, Adri Mari Mainza, Aubrey Engineering Tumbling mills are considered to be among the most energy intensive devices in comminution circuits and are designed to achieve size reduction and transport. These functions are influenced by the mill speed, filling and the configuration of the lifter bars attached to the mill shell (height, width, face angle, etc.). The lifter height has been shown to influence the charge motion and power draw of the mill. Most of the predictive power models used in industry do not consider lifter heights as a variable. In comminution, Positron Emission Particle Tracking (PEPT) is used to track the charge motion of particles in tumbling mill systems. The data has been used to derive a velocity profile for particle motion between the mill shell and centre of circulation (COC), a region that highlights the distinct particle motion in tumbling mills. In prior work, a laboratory scale mill and PEPT was used to develop a velocity profile model incorporating the lifter height influence on charge motion. The agreement between PEPT and the model predictions was limited to regions closest to the mill shell and the analysis was restricted for conditions where the lifter height was significantly smaller than the particle diameter. The current study aimed to supplement the PEPT results by using the Discrete Element Method (DEM) to simulate the collective effect of individual particle interactions on the charge motion. The DEM results were used to analyse the influence of the lifter height on the charge motion, velocity profile and power draw for an identical tumbling mill system. The PEPT and DEM results agreed on charge motion and power draw changes. The assumption of a constant axial pressure drop (dP/dx) along the cross-section of the mill resulted in deviations between DEM and model predictions of the velocity profile. The calculated axial pressure drop varied non-linearly along the mill radius and followed a similar trend at all operating conditions. The relationship between the velocity profile and axial pressure drop was found to vary non-linearly and followed a similar trend to the stress-strain relation of granular media. It is recommended that further research be conducted on the axial pressure drop and its influence on the velocity profile. 2019-05-15T07:35:24Z 2019-05-15T07:35:24Z 2018 2019-05-14T11:19:20Z Master Thesis Masters MSc http://hdl.handle.net/11427/30087 eng application/pdf Department of Chemical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Engineering Uys, Adri Mari The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| thesis_degree_str | Master's |
| title | The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| title_full | The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| title_fullStr | The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| title_full_unstemmed | The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| title_short | The study of the influence of the lifter height on the charge motion, velocity profile and power draw of a laboratory tumbling mill using DEM simulations |
| title_sort | study of the influence of the lifter height on the charge motion velocity profile and power draw of a laboratory tumbling mill using dem simulations |
| topic | Engineering |
| url | http://hdl.handle.net/11427/30087 |
| work_keys_str_mv | AT uysadrimari thestudyoftheinfluenceofthelifterheightonthechargemotionvelocityprofileandpowerdrawofalaboratorytumblingmillusingdemsimulations AT uysadrimari studyoftheinfluenceofthelifterheightonthechargemotionvelocityprofileandpowerdrawofalaboratorytumblingmillusingdemsimulations |