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Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores
Mineral hydration is known to result in low flotation recoveries and grades within primary platinum group element ores worldwide. This is because the phyllosilicate minerals derived from hydration reactions of silicate minerals (i) form electrostatic coatings on valuable minerals that in turn hinder...
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| Format: | Thesis |
| Language: | English |
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Department of Chemical Engineering
2022
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| _version_ | 1867613254595903488 |
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| access_status_str | Open Access |
| author | Molifie, Andrea |
| author2 | Mcfadzean, Belinda |
| author_browse | Mcfadzean, Belinda Molifie, Andrea |
| author_facet | Mcfadzean, Belinda Molifie, Andrea |
| author_sort | Molifie, Andrea |
| collection | Thesis |
| description | Mineral hydration is known to result in low flotation recoveries and grades within primary platinum group element ores worldwide. This is because the phyllosilicate minerals derived from hydration reactions of silicate minerals (i) form electrostatic coatings on valuable minerals that in turn hinders collector adsorption, (ii) alter the viscosity of the slurry leading to poor gas dispersion and (iii) decrease the concentrate grade due to naturally-floating gangue. Sodium metasilicate was investigated because its dispersant, rheology modifying, and depressant properties could prove promising in combating the problems associated with these ore types. Quantitative evaluation by scanning electron microscopy (QEMSCAN) analysis revealed large quantities of serpentine and talc present within the ore sample used in this study, which led to a poor flotation response, as indicated by batch flotation tests. Using sodium metasilicate improved the recoveries and grades at high dosages (>1000 g/t). A suite of techniques was chosen to decouple sodium metasilicates' effects to answer why an improved flotation performance occurred. The zeta potential experiments indicate that improved recoveries are, in part, as a result of the reversal of serpentines surface charge, creating electrostatic repulsion between serpentine and valuable minerals which prevents the coating of valuable minerals by serpentine slimes. This corresponded with improved recoveries of a PGM proxy in the presence of serpentine slimes and a high sodium metasilicate dosage. Ore dilution and rheology tests indicate that decreased viscosity at high dosages also improved recoveries. This was supported by slower particle settling rates at high sodium metasilicate dosages during particle settling measurements. Talc micro-flotation tests revealed that the depression of talc occurred at higher sodium metasilicate dosages, which improved concentrate grade. This was supported by a QEMSCAN concentrate analysis of the sodium metasilicate batch flotation concentrates, which confirmed that talc, and other associated silicate minerals, were depressed at high sodium metasilicate dosages. The processing of near-surface altered ores is becoming an increasing problem worldwide and the use of sodium metasilicate proved valuable in mitigating the problems associated with the altered ore investigated in this study. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/35888 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:13.838Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| 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:11427/35888 Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores Molifie, Andrea Mcfadzean, Belinda Becker Megan Geldenhuys, Stefan Alteration phyllosilicate slimes platinum group minerals Mineral hydration is known to result in low flotation recoveries and grades within primary platinum group element ores worldwide. This is because the phyllosilicate minerals derived from hydration reactions of silicate minerals (i) form electrostatic coatings on valuable minerals that in turn hinders collector adsorption, (ii) alter the viscosity of the slurry leading to poor gas dispersion and (iii) decrease the concentrate grade due to naturally-floating gangue. Sodium metasilicate was investigated because its dispersant, rheology modifying, and depressant properties could prove promising in combating the problems associated with these ore types. Quantitative evaluation by scanning electron microscopy (QEMSCAN) analysis revealed large quantities of serpentine and talc present within the ore sample used in this study, which led to a poor flotation response, as indicated by batch flotation tests. Using sodium metasilicate improved the recoveries and grades at high dosages (>1000 g/t). A suite of techniques was chosen to decouple sodium metasilicates' effects to answer why an improved flotation performance occurred. The zeta potential experiments indicate that improved recoveries are, in part, as a result of the reversal of serpentines surface charge, creating electrostatic repulsion between serpentine and valuable minerals which prevents the coating of valuable minerals by serpentine slimes. This corresponded with improved recoveries of a PGM proxy in the presence of serpentine slimes and a high sodium metasilicate dosage. Ore dilution and rheology tests indicate that decreased viscosity at high dosages also improved recoveries. This was supported by slower particle settling rates at high sodium metasilicate dosages during particle settling measurements. Talc micro-flotation tests revealed that the depression of talc occurred at higher sodium metasilicate dosages, which improved concentrate grade. This was supported by a QEMSCAN concentrate analysis of the sodium metasilicate batch flotation concentrates, which confirmed that talc, and other associated silicate minerals, were depressed at high sodium metasilicate dosages. The processing of near-surface altered ores is becoming an increasing problem worldwide and the use of sodium metasilicate proved valuable in mitigating the problems associated with the altered ore investigated in this study. 2022-03-03T21:06:05Z 2022-03-03T21:06:05Z 2021 2022-03-03T21:04:21Z Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/35888 eng application/pdf Department of Chemical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Alteration phyllosilicate slimes platinum group minerals Molifie, Andrea Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| thesis_degree_str | Doctoral |
| title | Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| title_full | Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| title_fullStr | Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| title_full_unstemmed | Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| title_short | Investigating the use of sodium metasilicate to improve the flotation performance of altered PGE ores |
| title_sort | investigating the use of sodium metasilicate to improve the flotation performance of altered pge ores |
| topic | Alteration phyllosilicate slimes platinum group minerals |
| url | http://hdl.handle.net/11427/35888 |
| work_keys_str_mv | AT molifieandrea investigatingtheuseofsodiummetasilicatetoimprovetheflotationperformanceofalteredpgeores |