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Use of the capacitance method to estimate the volumetric water content of gold tailings
Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2026
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University of Pretoria
2026
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| _version_ | 1867613721332809728 |
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| access_status_str | Open Access |
| author2 | Smit, Martha Sophia |
| author_browse | Smit, Martha Sophia |
| author_facet | Smit, Martha Sophia |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2026 |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/107571 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:38.899Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/107571 Use of the capacitance method to estimate the volumetric water content of gold tailings Smit, Martha Sophia opeyemi.fajire@tuks.co.za Tiago, A.V. Gaspar Fajire, Opeyemi UCTD Sustainable Development Goals (SDGs) Volumetric Water Content Capacitance Sensor Apparent Dielectric Permittivity Suction Gold Tailings Tailings Storage Facility Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2026 An excess of water in tailings storage facilities poses a risk to their stability. To determine the water content of tailings, direct and indirect methods can be used. This study investigates the performance of capacitance sensors in measuring dielectric permittivity to estimate the volumetric water content (VWC) of gold tailings.The gold tailings considered were from the East Rand in South Africa. Preliminary tests were conducted to gain an understanding of the slurry deposition procedure, control of initial density, the effect of the test environment, and direct determination of volumetric water content, with the purpose of refining the test procedure. It was found that temperature influenced dielectric permittivity values, and it was not possible to vary the initial density over a wide range using slurry deposition.Two main experimental campaigns were undertaken. The purpose of the first set of tests was to investigate the effect of temperature on the dielectric permittivity of the components of unsaturated tailings (solids, water, and air) and of a sample of unsaturated tailings. The purpose of the second set of tests was to investigate the effect of initial density on the soil-specific calibration of dielectric permittivity to volumetric water content. Due to the difficulty in controlling the initial density of slurry-deposited gold tailings, a modified consolidometer was developed. This slurry consolidometer enabled the incorporation of numerous sensors into the sample, particularly relatively large commercially available TDR sensors. After consolidating the samples to specific densities, they were allowed to dry while measuring the water content, ranging from full saturation to residual water content.It was found that an increase in temperature decreased the dielectric permittivity of all components of unsaturated tailings (solids, water, and air) when they were considered in isolation. The range of change in dielectric permittivity for the considered temperature range was the widest for potable water and leached gold tailings water. Over a temperature range from 20 to 60 °C, the change in apparent dielectric permittivity was approximately 25. Counterintuitively, the behaviour of the unsaturated tailings samples (comprising solids, water, and air) was the inverse of what was observed when each constituent was considered individually. An increase in temperature increased the dielectric permittivity. The range of change was 8.3 for a temperature change of 40 °C for an unsaturated gold tailings sample. The effect of initial density on the performance of TDR sensors were also considered. Within the first five days of drying, the apparent dielectric permittivity initially increased despite a reduction in the water content of the sample. Thereafter, the apparent dielectric permittivity decreased as the volumetric water content decreased throughout the drying process. This was found to be the influence of the temperature increase that occurred in the samples as a result of the applied heat.Third-degree polynomial calibration models were developed to estimate the volumetric water content during drying, for each sample prepared at different initial densities. The individual third-degree polynomials (for each initial void ratio) predicted the volumetric water content of gold tailings samples to an accuracy of ±0.02 𝑐𝑚3/𝑐𝑚3 compared to the accuracy of about ±0.05 𝑐𝑚3/𝑐𝑚3 from existing published models. To obtain a single model that is sufficient to estimate the volumetric water content of gold tailings over a wide range of densities, a third-degree polynomial model was developed to account for the varying densities while estimating the volumetric water content in gold tailings. The multivariate model was able to estimate the volumetric water content across all samples, with the maximum error being ±0.014 𝑐𝑚3/𝑐𝑚3.These findings demonstrate that accounting for temperature and density effects can substantially improve the accuracy of capacitance-based volumetric water content measurements in gold tailings. The developed calibration framework offers a practical reference for interpreting in situ water content measurements in tailings storage facilities, supporting improved moisture monitoring under variable environmental conditions. Civil Engineering MEng (Geotechnical Engineering) Unrestricted Faculty of Engineering, Built Environment and Information Technology SDG-11: Sustainable cities and communities 2026-01-27T06:55:56Z 2026-01-27T06:55:56Z 2026-05-09 2026-01-22 Dissertation * April (A2026) http://hdl.handle.net/2263/107571 https://doi.org/10.25403/UPresearchdata.31129708, https://doi.org/10.25403/UPresearchdata.31129906 en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/octet-stream University of Pretoria |
| spellingShingle | UCTD Sustainable Development Goals (SDGs) Volumetric Water Content Capacitance Sensor Apparent Dielectric Permittivity Suction Gold Tailings Tailings Storage Facility Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title | Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title_full | Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title_fullStr | Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title_full_unstemmed | Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title_short | Use of the capacitance method to estimate the volumetric water content of gold tailings |
| title_sort | use of the capacitance method to estimate the volumetric water content of gold tailings |
| topic | UCTD Sustainable Development Goals (SDGs) Volumetric Water Content Capacitance Sensor Apparent Dielectric Permittivity Suction Gold Tailings Tailings Storage Facility |
| url | http://hdl.handle.net/2263/107571 https://doi.org/10.25403/UPresearchdata.31129708, https://doi.org/10.25403/UPresearchdata.31129906 |