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A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics
Comminution is an important operation in the minerals processing industry. In both traditional and stirred mills, single-sized grinding beads are used, along with multiple passes through the mills, to achieve a sufficient size-reduction ratio. It is plausible to expand the size reduction capabilitie...
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| Format: | Thesis |
| Language: | English English |
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Department of Chemical Engineering
2026
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| _version_ | 1867613155838918656 |
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| access_status_str | Open Access |
| author | Sievers, Wilco |
| author2 | Mainza, Aubrey |
| author_browse | Mainza, Aubrey Sievers, Wilco |
| author_facet | Mainza, Aubrey Sievers, Wilco |
| author_sort | Sievers, Wilco |
| collection | Thesis |
| description | Comminution is an important operation in the minerals processing industry. In both traditional and stirred mills, single-sized grinding beads are used, along with multiple passes through the mills, to achieve a sufficient size-reduction ratio. It is plausible to expand the size reduction capabilities of a mill using multiple-sized grinding beads in the mill. For this study, the discrete element method (DEM) was used to simulate dry size-segregated systems in a vertical stirred mill. These size-segregated systems were evaluated at different impeller speeds and weight distributions. The dry systems were susceptible to the Brazilian nut effect. Furthermore, it was found that excessive impeller speeds did not subsequently increase the overall collision modulus. The overall modal collision intensity for particle collisions was maximised between 350 rpm and 500 rpm where sufficient mixing and impeller speed were facilitated. At excessive speeds past 700 rpm the collision modulus plateaued. Excessive addition of smaller particles reduced the total energy applied to particle-particle collisions which also reduced the overall systems collision modulus. The results presented in this study could be considered as an introduction to dry size-segregated media in a vertical stirred mill. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/42677 |
| institution | University of Cape Town (South Africa) |
| language | English eng |
| last_indexed | 2026-06-10T12:31:38.662Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| 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:11427/42677 A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics Sievers, Wilco Mainza, Aubrey DEM vertical stirred mill size-segregated impeller speeds weight distribution grind characteristics Comminution is an important operation in the minerals processing industry. In both traditional and stirred mills, single-sized grinding beads are used, along with multiple passes through the mills, to achieve a sufficient size-reduction ratio. It is plausible to expand the size reduction capabilities of a mill using multiple-sized grinding beads in the mill. For this study, the discrete element method (DEM) was used to simulate dry size-segregated systems in a vertical stirred mill. These size-segregated systems were evaluated at different impeller speeds and weight distributions. The dry systems were susceptible to the Brazilian nut effect. Furthermore, it was found that excessive impeller speeds did not subsequently increase the overall collision modulus. The overall modal collision intensity for particle collisions was maximised between 350 rpm and 500 rpm where sufficient mixing and impeller speed were facilitated. At excessive speeds past 700 rpm the collision modulus plateaued. Excessive addition of smaller particles reduced the total energy applied to particle-particle collisions which also reduced the overall systems collision modulus. The results presented in this study could be considered as an introduction to dry size-segregated media in a vertical stirred mill. 2026-01-26T07:21:53Z 2026-01-26T07:21:53Z 2025 2026-01-26T07:14:30Z Thesis / Dissertation Masters MSc http://hdl.handle.net/11427/42677 en eng application/pdf Department of Chemical Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | DEM vertical stirred mill size-segregated impeller speeds weight distribution grind characteristics Sievers, Wilco A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| thesis_degree_str | Master's |
| title | A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| title_full | A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| title_fullStr | A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| title_full_unstemmed | A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| title_short | A DEM numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| title_sort | dem numerical modelling approach to simulating size segregation of media in a stirred mill and effects on grind characteristics |
| topic | DEM vertical stirred mill size-segregated impeller speeds weight distribution grind characteristics |
| url | http://hdl.handle.net/11427/42677 |
| work_keys_str_mv | AT sieverswilco ademnumericalmodellingapproachtosimulatingsizesegregationofmediainastirredmillandeffectsongrindcharacteristics AT sieverswilco demnumericalmodellingapproachtosimulatingsizesegregationofmediainastirredmillandeffectsongrindcharacteristics |