PhD scholarships: ARC Centre of Excellence - Enabling eco-efficient beneficiation of minerals

Experimental investigation of breakage mechanisms on fracture along grain boundaries

This project aims to understand the underlying mechanisms which lead to breakage along the grain boundaries and the liberation of ore minerals. In this project different combinations of stressing mechanisms (e.g. compression, tension, impact, and shear) applied through different breakage devices such as crushers, ball mills, high pressure grinding rolls, and Vertical Roller Mills (VRM) will be applied to synthetic and real rock particles with different textures and mineralogy. The experimental work will also consider variations in the device configuration such as balls and liners of diverse physical properties (i.e. different Young’s modulus) to separate the influence of ore characteristics and device properties over breakage at comminution scale.

The synthetic particles produced by either 3D printing or geopolymers with predefined and simple textures and real ore samples with distinctively different textures and mineralogy will be studied using a set of characterisation techniques such as 3D X-ray tomography and quantitative SEM-based mineral analysis.

Associate Professor Mohsen Yahyaei

m.yahyaei@uq.edu.au

This project forms part of the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals. The aim of the Centre is to develop transformational technologies to ensure that the mining and minerals processing industry can become both economically feasible and environmentally sustainable.

The aim of this work is to investigate the relationship between surface chemical heterogeneity at the micrometre scale with hydrophobicity and particle-bubble interaction forces. Surface chemistry information will be acquired using surface analysis, namely Time-of-Flight Secondary Ion Mass Spectrometry - a highly surface sensitive imaging technique – and correlated with particle-bubble forces through Atomic Force Microscopy measurements. The combination of these techniques will provide a deep fundamental understanding of the mechanisms underpinning particle-bubble interactions in flotation and the limits of chemical heterogeneity that result in a measurable impact on the hydrophobicity required for flotation.

This work will be a collaboration with the University of South Australia and will have synergies with other research projects within the Centre.

Benefits – This work will advance our current understanding of the particle-bubble interaction mechanisms, in particular, of coarse particles and quantify the limits of surface chemical heterogeneity on mineral separation. This fundamental understanding will be critical to the improvement of mineral flotation efficiency, especially for coarse particle flotation.

Dr Susana Brito e Abreu

s.britoeabreu@uq.edu.au

This project forms part of the ARC Centre of Excellence on Eco-Efficient Beneficiation. The aim of the Centre is to develop transformational technologies to ensure that the mining and minerals processing industry can become both economically feasible and environmentally sustainable.

Mineral flotation is one of the primary stages of minerals processing.  This project is situated at the intersection of the development of cutting edge technologies and their application in today’s minerals processing industry.

The aim of the work is to investigate a novel reagent delivery mechanism within the flotation process, whereby the reagents are introduced via the surfaces of bubbles rather than through bulk solution. This will be done in order to optimise reagent adsorption onto both very coarse and very fine particles to increase their recovery. If successful, this work will improve the efficacy of the flotation process, reducing the amount of valuable material lost to mineral tailings.

The work is expected to produce the following benefits:

• An understanding of the fundamentals of reagent distribution as a function of size and liberation on both very coarse and very fine particles
• An evaluation of the effect of collector addition methods on reagent distribution and subsequent flotation of coarse and fine particles, including:
  • Conventional flotations vs. Split conditioning
  • For coarse particles – Conventional collector addition vs. Aerosol collector addition
  • For fine particles – Conventional collector addition vs. colloidal gas aphron collector addition

Dr Liza Forbes

l.forbes@uq.edu.au

We are seeking a full-time, highly motivated PhD candidate to perform high-quality research in the field of minerals flotation. The successful candidate will be working under the supervision of Prof Anh V. Nguyen at the School of Chemical Engineering. The candidate will join a multidisciplinary team in partnership with industry partners. This scholarship is funded by the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals.

This project aims to fundamentally quantify the combined role of the frothers and hydrophobic particles in controlling froth drainage and coarsening by using state-of-the-art techniques such as sum-frequency generation spectroscopy, thin-film balance, and molecular dynamic simulation. The film drainage and rupture in the presence of coarse particles and frother molecules with different types and concentrations will be investigated and linked with the bubble coarsening in froth transient and equilibrium stability. Advanced knowledge obtained from this project will be used to optimize the frother type and dosage to promote the performance of coarse composite particle flotation.

Professor Anh Nguyen

Anh.Nguyen@eng.uq.edu.au

We are seeking a full-time, highly motivated PhD candidate to perform high-quality research in the field of mineral processing. The successful candidate will be working under the supervision of Prof Anh V. Nguyen at the School of Chemical Engineering. The candidate will join a multidisciplinary team in partnership with industry partners. This scholarship is funded by the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals.

This project aims to quantify separation performance through partition curves via X-ray CT scanning in combination with other techniques such as atomic force microscopy and flotation. Conventionally, partition curves describing separating efficiency can be obtained by float-and-sink (FaS) experiments and analysis, which consume toxic and environmentally hazardous heavy liquids. The FaS methodology is also time-consuming and cannot be deployed for on-line real-time analysis and control. The application of High-Resolution X-ray Microcomputed Tomography (HRXMT) and specialised software allows for determining the characteristics of various particles such as coal, quartz, and gangue minerals. The knowledge developed from this project will be significant for a sustainable and environmentally friendly mining industry.

Professor Anh Nguyen

Anh.Nguyen@eng.uq.edu.au

This project aims to develop stimuli-responsive soft materials (foams and emulsions) using designed biomolecules (proteins and peptides). Peptides or proteins are informational polymers made up of amino acids and are increasingly viewed as key building blocks to achieve specific functions owing to their biocompatibility, sustainability, and ease of functionalization, coupled with facile methods for their economic manufacture. Enabled by the diversity of the 20 naturally occurring amino acids, there is a large sequence and structural solution space for design. This work aims to explore the functionality of using biomolecules to stabilise foams or emulsions, and the potential for switching that functionality based on different switching mechanisms. This study seeks to develop the functionality offered by biomolecules such as peptides or proteins that change conformation when adsorbed to an interface in controlling the nature of foams, emulsions, and flocculated suspensions. The designed biomolecules as well as the developed soft materials have great potential in a wide range of applications in mineral processing, pharmaceuticals, food industry, agriculture, etc.

Associate Professor Chun-Xia Zhao

z.chunxia@uq.edu.au

Development of novel bio-inspired biomolecules for controlling colloidal stability

This project aims to design biomolecules (peptides and proteins) for controlling the stability of colloid particles. A series of biomolecules (peptides and proteins) will be designed to have different structures and surface activity. Peptides will be synthesised using chemical methods, while proteins will be expressed in E. Coli and produced using a simple chromatography-free separation method. The interactions between these designed biomolecules and colloid particles with different charge, size and hydrophobicity will be systematically studied using a variety of techniques including settling tests, depletion adsorption isotherms, turbidity measurements, atomic force microscopy, zeta-potential, dynamic light scattering and scanning electron microscopy. These designed biomolecules along with the fundamental understanding of their interactions with colloid particles will improve handling and processing of particles suspensions for various applications in mineral processing, water purification, wastewater and sewage treatment, etc.

Associate Professor Chun-Xia Zhao

z.chunxia@uq.edu.au

The aim of this study is to explore the implications of full cleaning of the flotation product in a range of applications and in turn quantify the true selectivity of flotation. The Reflux Flotation Cell developed by the University of Newcastle will be used in this study. It operates via a concentrated bubbly zone, thus eliminating the myriad of issues that arise from the uncertain instabilities of the froth phase. Counter-current washing of the bubbly zone will be used to promote extreme levels of product cleaning to achieve maximum grade. To explore the true benefits of improved selectivity for specific minerals, this level of cleaning will be further exploited as part of the assessment of improved selectivity through chemistry to ensure only the hydrophobic particles are recovered, free of entrained ultrafine gangue or slimes. The results can then be compared to the theoretical limit derived from SEM and X-ray CT scanning. This project has the potential to deliver significantly improved product cleaning, and hence transformational change. Old tailings dams might be reprocessed to recover minerals for metals, allowing and even funding the rehabilitation of the land. Laureate Professor Kevin Galvin at the University of Newcastle will be a co-supervisor of this study. The candidate will work in laboratory and industry plants.

Professor Yongjun Peng

yongjun.peng@uq.edu.au