Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice
The quantitative effect of particle shape, porosity, wettability, particle size, and solution viscosity on the residence time distribution (RTD) profiles of non-reactive, steady-state, drip-irrigated ore beds characteristic of heap leaching systems is presented. Results were obtained using step-up t...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-02-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/13/2/267 |
| _version_ | 1797619092642856960 |
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| author | Michael D. Odidi Marijke A. Fagan-Endres Susan T. L. Harrison |
| author_facet | Michael D. Odidi Marijke A. Fagan-Endres Susan T. L. Harrison |
| author_sort | Michael D. Odidi |
| collection | DOAJ |
| description | The quantitative effect of particle shape, porosity, wettability, particle size, and solution viscosity on the residence time distribution (RTD) profiles of non-reactive, steady-state, drip-irrigated ore beds characteristic of heap leaching systems is presented. Results were obtained using step-up tracer tests and allowed for the analysis of preferential flow behaviour within the systems. The key findings were as follows. Increased particle sphericity enhanced channelling in beds of smaller particles, but not for larger particle sizes. Higher particle wettability caused greater liquid dispersion during both initial wetting studies and at steady-state fluid flux. Higher porosity levels and the inclusion of fines in mixed sized beds resulted in longer average solute residence times, higher liquid hold-up, longer solution and tracer breakthrough times, and increases in drain-down moisture percentages. Increasing the irrigation fluid’s viscosity, reflective of the increase in ionic concentrations in leach solutions, reduced both the solution and tracer breakthrough times and increased dispersion with signs of more discontinuous or isolated fluid volumes at steady-state. These results highlighted the importance of the inclusion of fines in agglomerated beds to improve uniform wetting especially those with low to moderate particle porosities (<2.5 m<sup>2</sup>/g specific surface area). The viscosity results suggest that there may be changes in preferential flow extent, due to variations in viscosity owing to the increasing sulphate concentration within the liquid phase in heaps and with time. |
| first_indexed | 2024-03-11T08:22:06Z |
| format | Article |
| id | doaj.art-5e68e866e3ea46b78d2bf3f70ccb980a |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-11T08:22:06Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-5e68e866e3ea46b78d2bf3f70ccb980a2023-11-16T22:19:10ZengMDPI AGMinerals2075-163X2023-02-0113226710.3390/min13020267Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching PracticeMichael D. Odidi0Marijke A. Fagan-Endres1Susan T. L. Harrison2Centre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Cape Town 7700, South AfricaCentre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Cape Town 7700, South AfricaCentre for Bioprocess Engineering Research, Department of Chemical Engineering, University of Cape Town, Cape Town 7700, South AfricaThe quantitative effect of particle shape, porosity, wettability, particle size, and solution viscosity on the residence time distribution (RTD) profiles of non-reactive, steady-state, drip-irrigated ore beds characteristic of heap leaching systems is presented. Results were obtained using step-up tracer tests and allowed for the analysis of preferential flow behaviour within the systems. The key findings were as follows. Increased particle sphericity enhanced channelling in beds of smaller particles, but not for larger particle sizes. Higher particle wettability caused greater liquid dispersion during both initial wetting studies and at steady-state fluid flux. Higher porosity levels and the inclusion of fines in mixed sized beds resulted in longer average solute residence times, higher liquid hold-up, longer solution and tracer breakthrough times, and increases in drain-down moisture percentages. Increasing the irrigation fluid’s viscosity, reflective of the increase in ionic concentrations in leach solutions, reduced both the solution and tracer breakthrough times and increased dispersion with signs of more discontinuous or isolated fluid volumes at steady-state. These results highlighted the importance of the inclusion of fines in agglomerated beds to improve uniform wetting especially those with low to moderate particle porosities (<2.5 m<sup>2</sup>/g specific surface area). The viscosity results suggest that there may be changes in preferential flow extent, due to variations in viscosity owing to the increasing sulphate concentration within the liquid phase in heaps and with time.https://www.mdpi.com/2075-163X/13/2/267preferential flowheap leachingcapillary actionparticle sizeporositywettability |
| spellingShingle | Michael D. Odidi Marijke A. Fagan-Endres Susan T. L. Harrison Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice Minerals preferential flow heap leaching capillary action particle size porosity wettability |
| title | Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice |
| title_full | Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice |
| title_fullStr | Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice |
| title_full_unstemmed | Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice |
| title_short | Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice |
| title_sort | residence time distribution analysis of drip irrigated beds the effect of material and fluid properties with implications for heap leaching practice |
| topic | preferential flow heap leaching capillary action particle size porosity wettability |
| url | https://www.mdpi.com/2075-163X/13/2/267 |
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