CHEMISTRY OF NOVEL HYDROPHOBIC AND SELECTIVE INTERACTIONS

Research Program Leaders

Professor Karen Hapgood, Professor George Franks, Associate Professor Liza Forbes

Overview

The overall objective of Program 2 is to support robust, fast, and efficient separation technologies that are both selective and hydrophobic. This is achieved by studying the effect of hydrophobic reagents on the surface properties and floatability of mineral particles. There was considerable progress in 2022 across all three sub-programs. Some of the highlights are given below.

2.1 Development of Novel Flotation Collectors

The objective of this sub-program is to develop novel reagents to enhance mineral surface hydrophobicity. The key highlights were:

ƒ Improved understanding of adsorption of novel synthetic and biopolymers and surfactants (from Program 3) to a range of surfaces, investigated through quartz crystal microbalance measurements.

ƒ Development of stable oil-in-water emulsions for application in coarse particle recovery, using conventional and novel surfactants (from Program 3). The emulsions have been investigated through creaming rate, zeta potential and droplet size measurements

2.2 Development of Novel Delivery Systems

The objective of this sub-program is to examine new ways of introducing reagent chemistries into mineral processing systems. The key highlights were:

ƒ Investigations into stabilising both water-inoil and oil-in-water emulsions using starch, cellulose, and fly ash.

ƒ Hydrophobic talc particles can be recovered with the use of a novel hydrophobic emulsion binder. Initial investigation has commenced regarding pre-aggregating the particles with a polymeric flocculant prior to binder agglomeration.

ƒ The benefits of placing collector on surfaces of bubbles (rather than mineral particles) to enhance coarse particle hydrophobicity is being investigated.

ƒ A series of thermo-responsive polymers (PNIPAM-based) via the RAFT process have been screened for their ability to stabilise water-in-oil emulsions for binder agglomeration. The best candidate has been found to be effective in recovering hydrophobic talc particles.

2.3 Hydrophobic Interactions in Dewatering

The objective of the third sub-program is to exploit mineral surface properties to improve suspension dewatering. The key highlights were:

Some objectives for 2023:

ƒ Investigation of the spreading of oils on mineral surfaces via combinations of novel surfactants and polymers.

ƒ Measurement of contact angles of mineral surfaces when treated with emulsion droplets stabilised by conventional and novel surfactants (from Program 3).

Personnel involved in Program 2 for 2022

Chief Investigators

Prof David Beattie, UniSA

Dr Susana Brito e Abreu, UQ

A/Prof Liza Forbes, UQ

Prof George Franks, UOM

L/Prof Kevin Galvin, UON

ƒ A team of researchers covering molecular dynamics and density functional analysis, RAFT polymerisation, surface physics, and novel beneficiation has established a possible way forward to improve the recovery and concentration of rare earth minerals. The industry partner has signed on for a second study.

ƒ Agglomerating with oil-in-water emulsions and flocculating clay particles has been investigated. Further processing via pelletisation was shown to improve the solid-liquid separation.

ƒ Chalcopyrite was found to selectively flocculate from quartz suspensions using conventional polymers. The high molecular weight was demonstrated to be a key polymer property. The potential for conventional surfactant collectors to make those aggregates hydrophobic for selective recovery via froth flotation was demonstrated.

In addition, there has been strong collaboration with Program 3 researchers supporting all three subprograms including:

ƒ A range of bespoke RAFT polymers and surfactants have been synthesised to test functionality and selectivity with model mineral systems in flocculation and flotation.

ƒ An initial set of novel peptide flotation collectors and depressants has been developed and tested for metal ion and surface selectivity.

ƒ Investigation of the influence of preaggregating fine particles with polymer on the amount of hydrophobic binder required to agglomerate and recover those particles.

ƒ Characterisation of the adsorption of novel polymers (from Program 3) on to mineral surfaces.

ƒ Initial comparison of the influence of collector addition either through the solution phase (conventional) or through the gas phase (novel).

ƒ Systematic investigation of the selective aggregation of chalcopyrite from quartz using different polymers.

ƒ Investigation of the flotation of copper bearing minerals with conventional and novel polymers sourced from Program 3.

ƒ Studies of bubbles attaching to oil-coated minerals using an oil-infused polymer layer as a planar oil-water interface for initial studies of bubble collisions.

A/Prof Marta Krasowska, UniSA

Dr Ellen Moon, Deakin

Prof Bill Skinner, UniSA

Dr Anthony Stickland, UOM

Prof San H. Thang, Monash

Prof Erica Wanless, UON

Prof Grant Webber, UON

Prof Chun-Xia Zhao, UoA

Associate Investigators

Dr Eirini Goudeli, UOM

A/Prof Kizuku Kushimoto, UOM

Ms Amalie Moller, UniSA

Research Associates

Dr Negin Amini, Deakin

Dr Amir Beheshti, UniSA

Dr Nilanka Ekanayake, UOM

Dr Bo Fan, Monash

Dr Casey Thomas, UOM

Dr Shane Usher, UOM

Dr Isabella Verster, UQ

Dr Junyu Wang, UQ

Dr Joshua Willott, UON

Dr Unzile Yenial Arslan, UQ

PhD Students

Ms Regina Medeiros, UOM

Mr Azeez Aregbe, UOM

Miss Candice Brill, UQ

Mr Yunzhou Qian, UOM

Mr Lequan Zeng, UOM

Mr Yuxuan Luo, UOM

Technical Staff

Mr Raul Cavalida, UOM

Ms Laura Jukes, UOM

Undergraduate Students

Zheng Xie, UOM

Declan Falls, UOM

Wenqian Li, UOM

Joshua Fink, UOM

Weizhe Peng, UOM