- Title
- Erosive Wear in Mining: Development of a Wear Rate Estimation Methodology
- Creator
- Gomes de Oliveira, Caroline
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Erosive wear is the degradation of a surface material as a result of particle impacts. This kind of wear is a common engineering problem in any materials handling operation. It is normally solved by inspecting the sacrificial wear parts during scheduled maintenance and replacing them if required. Since the actual mechanisms involved in erosive wear are poorly understood in many situations, erosion rate predictions are often not accurate. Erosive wear in the mining industry particularly suffers from this poor understanding. This is because most erosive wear studies to date have been conducted with small particles impacting surfaces at high velocities. These conditions are far from those encountered in mining with extremely large particles and relatively low velocities involved. This restricted range of studies is likely to result from the fact that, although erosion testing plays a fundamental role in the study of materials erosion behaviour, no test setup developed to date can fairly reproduce the conditions found in the mining industry. This represents a major limitation in the understanding of erosive wear in mining. To address this limitation, a prototype impact tester has been developed at The University of Newcastle - Australia and has been used in this work to recreate the conditions relevant to the mining industry. It consists of a large rotating wheel fitted with internal buckets that are filled with erodent particles (approximately 300 kg). As the rig rotates, the internal buckets continuously lift the particles loaded into the tester and drop them into a chute that directs the particles to the wear liner sample surface. The particle recirculation creates a continuous flux impacting the tested samples. This tester is representative of the mining conditions in terms of particle velocities (< 10 m/s), particle size (20 mm) and particle flow (approximately 20 tons per hour). However, due to the recirculating nature of the tester, it presents significant time-dependent changes in particle characteristics during a test. As a test advances, particles quickly become rounder and smaller and, consequently, further away from the particles’ characteristics found in mining operations. These limitations, which are not at all considered in existing methodologies, lead to the hypothesis that only the initial slope of the erosion curves obtained from these tests are relevant to estimate the erosion rates occurring in service. However, the initial instantaneous erosion of the wear liners is physically impossible to measure. To address this limitation and to investigate the hypothesis, the approach adopted was firstly deducing the initial erosion rate by successfully continuum modelling the entire complex and time dependant testing system so that instantaneous rates of change can be considered. Secondly, the microstructures of the worn liners were examined and related to the wear mechanisms using Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) analyses. This was an important step to ensure the liners did not undergo time dependent modifications such as strain hardening and localised melting due to particles impact. Lastly, the materials’ actual erosion behaviours were obtained from the derived model by disregarding the time dependent particle degradation, which does not occur in the in-service conditions. These and more factors were carefully studied and a new test methodology was proposed. Preliminary applications to a limited set of data from a mine site found that the methodology developed within this thesis provided predictions within 10% of the site measurements. Additional examinations with site data are recommended for future work to further validate and refine the methodology. This preliminary validation suggests that the approach adopted is acceptable and that the resulting estimates of erosion rates can be readily compared to material performance on site. This leads to accurate wear liner lifespan estimation in the very unique conditions found in the mining sector, which is a significant improvement over the current understanding and practice.
- Subject
- erosive wear; mining; erosion testing; wear estimation; particle degradation; particle shape
- Identifier
- http://hdl.handle.net/1959.13/1494194
- Identifier
- uon:53739
- Rights
- Copyright 2023 Caroline Gomes de Oliveira
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 531 KB | Adobe Acrobat PDF | View Details Download |