- Title
- Assessing and optimising coarse particle flotation using the CoarseAIR™ separator
- Creator
- Crompton, Luke James
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2025
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- This work introduces the CoarseAIR™, a novel system utilizing a three-phase fluidized bed and a system of inclined channels to facilitate coarse particle flotation and internal size classification. Internal classification in the CoarseAIR™ was investigated in a series of continuous steady-state experiments at different inclined channel spacings. For each experimental series, a low-grade chalcopyrite ore was milled to a top size of 0.53 mm and methodically prepared to generate a consistent feed. The air rate to the system was adjusted to determine the impact of the gas flux on coarse particle flotation and overall system performance, with a focus on maximizing both copper recovery and coarse gangue rejection. A new feed preparation protocol led to low variability in the state of the feed, and in turn strong closure in the material balance. Hence, clear conclusions were drawn due to the high-quality datasets. Inclined channel spacings of z = 6 and z = 9 mm were used. The z = 9 mm spacing produced more favourable copper recovery and gangue rejection. Higher gas fluxes of 0.30 to 0.45 cm/s had a measurable, adverse effect on the recovery of the coarser hydrophobic particles, while the gas flux of 0.15 cm/s delivered the best performance. Here, the cumulative recovery was 90%, and mass rejection was 60% at 0.50 mm, while the +0.090 mm recovery was 83% with a gangue rejection of 85%. The system displayed robust performance across all conditions investigated. A new algorithm was developed to assess the coarse particle flotation performance of the CoarseAIR™ system. The objective was to quantify the partitioning of the hydrophobic particles of the feed to the overflow product concentrate stream and to the underflow reject stream, recognising the broad extent of the particle surface liberation. To assess the coarse particle flotation performance, steady state samples of the feed, overflow product concentrate, and underflow reject streams of the CoarseAIR™ were taken and the +90 m portions used to perform batch mechanical cell flotation kinetic tests. Measurement of the flotation kinetics of all three streams was undertaken, including the ultimate recoveries of the hydrophobic particles. The algorithm was constrained by the need to describe the flotation kinetics of all three streams while also adhering to full material balance requirements within each stream and between the hydrophobic components of the three streams. The algorithm produced an overall partition curve for the CoarseAIR™ separator covering the size range from 90 ‒ 600 μm, describing the probability of a particle having a given rate constant, k, reporting to the overflow product concentrate. At a partition number of 0.50, the value of k is referred to as k50. Hydrophobic particles having this rate constant have an equal probability of reporting to the product and the reject. The partition curve was then determined as a function of the normalised rate constant, 𝑘/𝑘max. Here, the value of 𝑘50/𝑘max was ~0.06. Based on a previous study, this value can be used to infer a surface liberation of ~ 22%. The same approach was also applied to specific narrow size fractions, resulting in similar partition curves, with the value of 𝑘50𝑘max⁄ increasing with the particle size. The new algorithm was then improved in several ways. The flotation responses were deconvolved to the corresponding distributions of rate constants for the three streams, and in turn used to produce the partition curve for the coarse particle flotation. The algorithm used to produce the distribution of rate constants was driven towards a simple functional form by minimising its overall curvature. The steady state samples from any coarse particle flotation system can be assessed in this way. The reproducibility of the algorithm, and hence the uncertainty, using a batch mechanical cell to simulate the coarse particle flotation was then investigated. A mechanical cell was used to simulate the coarse particle flotation process, providing a means for preparing pseudo steady state feed, product, and reject samples. A comprehensive protocol for preparing the samples was established. The overall methodology was then repeated multiple times, providing a basis for quantifying the reproducibility and reliability of the methodology, confirming its robustness. This study investigated and optimised the operation of the CoarseAIR™. A novel method for assessing the performance of the coarse particle flotation system, indeed any system was then developed. The approach was then improved using distributed rate constants. The reproducibility of the algorithm was found to be very strong.
- Subject
- early gangue rejection; partition; coarse particle flotation; CoarseAIR; flotation; flotation kinetics; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1516460
- Identifier
- uon:56980
- Rights
- Copyright 2025 Luke James Crompton
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 794 KB | Adobe Acrobat PDF | View Details Download |