Physics of Novel System Hydrodynamics

NO TITLE LEADER & KEY PERSONNEL PROJECT SUMMARIES

P1.1 Quantifying Bulk and Surface Properties of Minerals

1 Application of X-ray CT scanning in describing mineral surface liberation with increasing grinding and applied breakage mechanisms

Leader: Prof Bill Skinner (UniSA)

Key Personnel:

Prof Mohsen Yahyaei (UQ)

Dr Catherine Evans, AI (UQ)

This project combines tomography and microscopy on ores to understand mineral deportment in coarse composite particles. Computed Tomography (CT) data has been collected using Xradia MicroXCT-400 sample preparation methodology developed using reference mineral materials. Parallel Quantitative Evaluation of Materials by Scanning Electron Microscopy (QEMSCAN) samples have been prepared for analysis. This will be followed by CT and QEMSCAN/optical analysis of synthetic, coarse composites. In the future, there is also an opportunity to investigate and apply a fast analysis methodology, previously developed by Associate Investigator, A/Prof Max Zanin and colleagues.

4 Investigation of breakage mechanisms on fracture along grain boundaries

Leader: Prof Mohsen Yahyaei (UQ)

Key Personnel:

Prof Chris Aldrich (Curtin)

Dr Catherine Evans, AI (UQ)

PhD Students:

Carolina Macarena Carvajal (UQ)

Bernard Selasie Agbenuvor (Curtin)

Rock particles are usually composed of minerals in the form of grains. This project investigates fundamentals of particle breakage along the grain boundaries using novel measurement techniques. The project looks to better understand the breakage of coarse particles and the partial liberation of valuable minerals to improve the energy efficiency of mineral processing circuits. Samples from Cu-Co oxide and Cu-Au sulphide ores were selected for exploratory phase and technique validation. Mineral characterisation via scanning electron microscopy (SEM-EDS) together with nanoindentation and optical microscopy was conducted to investigate the mechanical properties such as elasticity, hardness, and fracture toughness in individual minerals to assess ore breakage for the selected samples. This phase of the project is being performed at UQ. Density separation and sample characterisation (size distribution, porosity, hardness, chemical composition, and mineralogy) have been completed at Curtin for both the high and the low gangue rejection response.

2 Application of X-ray CT scanning in describing partition curves of mineral separators

Leader: Prof Anh V Nguyen (UQ)

Key Personnel:

Dr Catherine Evans, AI (UQ)

Prof Jan Miller, AI (Uni of Utah)

PhD Student: Quang Dao (UQ)

The project is developing an alternative to traditional Float-and-Sink (F-S) testing for the construction of methods used to generate partition curves. Samples of the feed, overflow and underflow streams of the preconcentration Pb-Zn ore circuit were scanned by X-Ray Computed Tomography (XRCT) with a new calibration and image analysis process. The samples were also analysed by F-S testing and were chemically assayed to develop a full size-by-size mass balance and reconciliation. The mass yield of the continuous separation process was determined, which is required for constructing the partition curves. Good agreement between the XRCT-based and the F-S based cumulative and partition curves was obtained, indicating the XRCT technology as a potential to replace conventional F-S analysis. The XRCT technology has potential to provide faster feedback than the F-S.

6 Characterisation of clays, including the role of salts in copper flotation

Leader: Prof Peter Scales (UOM)

Key Personnel:

A/Prof Liza Forbes (UQ)

Prof George Franks (UOM)

Dr Nathan Webster, PI (CSIRO)

PhD Student: Daniel Dodoo (UOM)

The presence of clays is ubiquitous to a range of mineral deposits. In flotation, clays cause viscosity and surface coating/selectivity issues and for hydrophobic clays, grade penalties in product streams. Fast and efficient characterisation of the amount and type(s) of clays present in a process stream and prediction of the consequences for flotation are still poor.

The initial focus of the work is the role of talc in copper ores and looks to develop new methods of characterisation of the relationship between aspect ratio, crystallinity, size and flotation response. The project is using new methods in XRD inclusive of partial least squares regression (PLSR) along with microscopy and is being conducted in conjunction with CSIRO. The aim is to characterise, predict and then control particle interactions and subsequent downstream effects. A range of clays from around the world and talc containing ores from Australian mines are being used for initial calibration of the technique, alongside laboratory flotation tests.

3 The manipulation and analysis of data from XRCT to quantify mineral surface liberation, with a particular focus on fine particle characterisation

Leader:

A/Prof Kym Runge (UQ)

Key Personnel:

Dr Catherine Evans, AI (UQ)

Dr Francisco Reyes, RA (UQ)

Prof Stephen Neethling, AI (Imperial College)

X-Ray Tomography (XRCT) is a non-destructive technique that has the potential to measure the composition and surface exposure of mineral particles using 3D images, overcoming stereological problems associated with 2D imaging. This project aims to test and further develop XRCT for various mineral processing applications. The project has established an engagement with an industrially funded research program to gain access to samples of different ores that have been subjected to breakage and flotation testing. Selected samples have been analysed by microscopy and the next step will be to analyse them using XRCT for comparison. The aim is to determine the mineral identification capability of XRCT and any particle size limitations.

7 Measurement of surface chemical heterogeneity at the micron scale

Leader: Prof Bill Skinner (UniSA)

Key Personnel:

A/Prof Marta Krasowska (UniSA)

Dr Susana Brito e Abreu (UQ)

The research looks to correlate grain boundary analysis using different analytical techniques. A set of experiments has been conducted involving cross-grain boundary correlation of atomic force microscopy (AFM) and ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectroscopy). Preparation of samples from copper sulphide ore (chalcopyrite, pyrite, silicates) is being analysed by Auger Microscopy/SPEEM (Photoemission Electron Microscopy) at UniSA as precursor to a synchrotron beamtime proposal.