Chemistry of Novel Hydrophobic and Selective Interactions

NO TITLE LEADER & KEY PERSONNEL PROJECT SUMMARIES

P2.2 Novel Delivery Systems

38 Binder adhesion of hydrophobic flocs

Leader: Prof George Franks (UOM)

Key Personnel:

Prof Peter Scales (UOM)

L/Prof Kevin Galvin (UON)

Increasing the speed at which solids can be removed from tailings is advantageous to industry, as water recovery and dry-stackable tailings are both an economic and environmental positive. In addition, reducing the amount of binder required by preaggregating the particles with a polymeric flocculant may reduce the overall reagent cost. The work has focused on comparing the use of a novel hydrophobic binder to agglomerate fine talc particles both with and without pre-aggregating the particles with a flocculant. Preliminary results indicate that the recovery of talc and the amount of hydrophobic binder required depends on the polymer charge density and the shear rate during both the polymer aggregation step and the oil agglomeration step. The aim is to avoid excessive shear during the aggregation step to prevent floc break up.

P2.3 Understanding the Influence of Hydrophobic Interactions in Dewatering

42 Thermodynamic guidance of RAFT polymerisation to control hydrophobicity at mineral surfaces

Leader: L/Prof Kevin Galvin (UON)

Key Personnel:

Prof Alister Page, AI (UON)

Prof San H. Thang (Monash)

Prof Bill Skinner (UniSA)

Prof Cyril O’Connor, AI (UCT)

Many rare earth elements (REE) are hard to upgrade because of size and surface chemistry similarities to gangue materials. Several preliminary experiments on an industrial sample have been completed using novel RAFT agents. Magnetic separation work reported by the UniSA node showed upgrade, indicating that most of the REE are locked in a minor monazite phase. A new strategy, built around fractionation and high quality desliming, was developed. The industry partner recently accepted a Phase 2 proposal for this work.

The theoretical aspect of the project currently focuses on the selective coordination of REE with lanmodulin-based peptides towards enabling selective magnetic separation of particular REE. It is envisaged that the project will investigate the performance of these biomolecules in thermo-responsive polymers for improved recovery.

39 Development of novel bespoke hydrophobic materials having large specific surface area to support selective separations

Leader: Prof Karen Hapgood (Swin)

Key Personnel:

Dr Ellen Moon (Deakin)

Prof San H. Thang (Monash)

Prof Steve Armes, PI (Sheffield)

Jord International

The use of high internal phase emulsions inclusive of recoverable RAFT polymers to aid agglomeration of ultrafine minerals is being explored. Work has been focused on the optimisation of emulsion composition for maximum recovery of talc, a hydrophobic gangue mineral commonly encountered in mineral processing.

A series of thermo-responsive RAFT polymers were synthesised with optimum stoichiometry to act as surfactants. The polymers were screened for their ability to form stable water-in-oil emulsions, which was assessed using confocal microscopy and rheology. Composition optimisation was completed for the most stable emulsions, to minimise the proportion of RAFT polymer surfactant and oil while maximising the agglomeration of ultrafine talc. Compared to ‘traditional’ emulsions containing a commercial surfactant, the novel emulsions were able to agglomerate up to 10% more talc. Further work will focus on assessing both the selectivity of the novel emulsions for hydrophobic minerals over hydrophilic minerals, and the recovery of the surfactant using its thermo-responsive properties.

43 Dewatering of small hydrophobic flocs

Leader:

Dr Anthony Stickland (UOM)

Key Personnel:

Prof Karen Hapgood (Swin)

Dr Ellen Moon (Deakin)

PhD Students:

Yuxuan Luo (UOM)

Yunzhou Qian (UOM)

This project aims to improve tailings dewatering behaviour using hydrophobic agglomeration and pelletisation. A model tailings experimental system using clay and a mineral oxide has been developed and used to systematically demonstrate the effect of clay on tailings filtration. Addition of the emulsion to the model tailings system without any shear has improved the permeability but had a negative impact on compressibility, indicating aggregation but not densification. Gentle shearing using a raked cylinder densified the aggregates, but with insufficient impact at low oil doses. Investigating the use of a prototype screw pelletiser is ongoing to better control the pelletisation conditions and have produced large pellets using polymer-flocculated clay. From a fundamental perspective, microscopy methods and particle-scale numerical techniques are being used to study emulsion breaking, oil spreading, particle agglomeration and pelletisation.

41 Investigation of direct reagent addition to bubble surfaces via the gas phase on hydrophobic particle recovery

Leader: A/Prof Liza Forbes (UQ)

Key Personnel:

Prof George Franks (UOM)

Ms Isabella Verster, RA (UQ)

PhD Student:

Candice Brill (UQ)

This project looks to understand the limitations of coarse particle flotation on real ore samples. Bulk ore samples have been sourced and have been processed into 1 kg aliquots. Work has been focused on characterising collectors based on surface tension. The flotation experimental program has been amended to include some work using a conventional mechanical flotation cell but this will be followed by experiments in the HydroFloatTM

44 Application of responsive synthetic and biopolymers through reversible switching from hydrophilic to hydrophobic conformations

Leader: Prof George Franks (UOM)

Key Personnel:

Prof Erica Wanless (UON)

Prof San H. Thang (Monash)

PhD Students:

Regina Medeiros (UOM)

Lequan Zeng (UOM)

The focus of the project is to compare commercially available polymers and reagents to novel reagents in the flocculation/flotation recovery of fine chalcopyrite particles. Preliminary results indicate that certain polymers can selectively flocculate chalcopyrite particles over quartz particles. A key finding is that high to ultrahigh molecular weight polymers are required for effective aggregation. The novel reagents investigated to date are relatively low in molecular weight so have not been effective flocculants. The addition of frother and collector to chalcopyrite suspensions containing commercial poly acrylamide flocculants enable the particles to segregate to the froth phase upon shaking of a glass jar. The project has the potential to improve recovery of fine chalcopyrite particles normally lost to tailings.