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The challenges associated with footwall clay in offshore diamond mining
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613990299893760 |
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| access_status_str | Open Access |
| author | Makhubelo, Dumisani Nation |
| author2 | Fouche, Nanine |
| author_browse | Fouche, Nanine Makhubelo, Dumisani Nation |
| author_facet | Fouche, Nanine Makhubelo, Dumisani Nation |
| author_sort | Makhubelo, Dumisani Nation |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/126993 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:44:55.028Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/126993 The challenges associated with footwall clay in offshore diamond mining Makhubelo, Dumisani Nation Fouche, Nanine Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Geotechnical engineering Diamond mines and mining Kimberlite Remote sensing Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Offshore environments on the west coast of southern Africa are home to a vast resource of gem-quality diamonds. Diamond-bearing Kimberlite pipes in the interior of the continent were extensively eroded by the Orange River drainage basin over millions of years. Diamonds released from kimberlites were carried hundreds of kilometers and deposited at the Orange River mouth. In the early 1950s, techniques to exploit this vast resource were developed, and continue to be improved to date. There are two types of diamond mining: onshore and offshore. This study focuses on offshore mining activities. Remote Operated Vehicles (crawlers) are the most common technology used to recover diamonds from depths up to -300m, IMDH (International Mining & Dredging Holdings) uses a crawler for mining operations. Studies have shown that diamonds commonly occur in free, yet well-packed, gravel layers overlying different types of footwall. Clay is the footwall of interest for this study as it has several negative implications related to excavation and processing in offshore diamond mining. Challenges related to footwall clay include crawler sinkage, poor traction, clogging and screen blinding to mention a few. This study explores the geotechnical properties of clays in Concession 2C to understand, explain, and suggest ways to mitigate the challenges. To understand the properties of the clay over which the crawler tracks, it was important to perform geotechnical laboratory tests. The following is a list of the tests that were performed: • Natural moisture content tests and Atterberg limits tests • Particle size distribution (hydrometer) tests • Pocket shear vane and penetrometer tests • One-dimensional consolidation (oedometer) tests • Triaxial (Unconsolidated Undrained) tests The lowest natural moisture content measured was 27% and the highest was 33%; these moisture contents aided in understanding the clay consistencies observed in the field. The particle size distribution tests revealed that half of the clay samples that were considered for this study had relatively high clay fractions which explained their medium to high plasticity on the Casagrande chart. The other half had significant silt fractions which was also evident in their plasticity. Shear vane and penetrometer tests were performed mostly for the purpose of creating consistency maps of the study area – there was no significant difference between the undrained shear strengths measured in the field and those measured in the laboratory. This confirmed the reliability of field data for use in mine planning and design. The clogging potential of the clays was investigated, and it was found that soft and firm clays have higher clogging potentials than stiff and hard clays. The clogging assessment was performed with the aid of a clogging chart adopted from Hollman & Thewes (2012). Triaxial (UU) test results were used to predict crawler mobility and the bearing capacity limits for the crawler based on its ground pressure, it was found that most of the clays had enough bearing capacity to support the crawler. The bearing capacity limits were determined using a mobility envelope model adopted from Machin (2018). Only one of the samples (0845_0500) showed significant sinkage due to its low undrained shear strength, sinkage was found to be negligible for the other samples. Knowledge of the clay’s undrained shear strength and compressibility can be used to predict clogging, sinkage and other challenges associated with a particular clay consistency. The findings from this study will aid in the development of safe mining procedures, mine planning and future crawler designs and modifications. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2023-02-23T13:48:34Z 2023-05-18T06:59:13Z 2023-02-23T13:48:34Z 2023-05-18T06:59:13Z 2023-03 Thesis http://hdl.handle.net/10019.1/126993 en_ZA en_ZA Stellenbosch University 162 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Geotechnical engineering Diamond mines and mining Kimberlite Remote sensing Makhubelo, Dumisani Nation The challenges associated with footwall clay in offshore diamond mining |
| title | The challenges associated with footwall clay in offshore diamond mining |
| title_full | The challenges associated with footwall clay in offshore diamond mining |
| title_fullStr | The challenges associated with footwall clay in offshore diamond mining |
| title_full_unstemmed | The challenges associated with footwall clay in offshore diamond mining |
| title_short | The challenges associated with footwall clay in offshore diamond mining |
| title_sort | challenges associated with footwall clay in offshore diamond mining |
| topic | Geotechnical engineering Diamond mines and mining Kimberlite Remote sensing |
| url | http://hdl.handle.net/10019.1/126993 |
| work_keys_str_mv | AT makhubelodumisanination thechallengesassociatedwithfootwallclayinoffshorediamondmining AT makhubelodumisanination challengesassociatedwithfootwallclayinoffshorediamondmining |