A New Dawn for Australian Minerals

Research Program Leaders: Laureate Professor Kevin Galvin, Laureate Professor Graeme Jameson and Professor Bill Skinner

Maximising the robustness, efficiency, and speed of separation are the critical elements of any transformational mineral beneficiation technology. This will be achieved by building knowledge and understanding of a broad range of novel hydrodynamic systems to determine the potential to approach the theoretical limits of separation, traversing the particle size range of interest.

In minerals processing, physical and physico-chemical properties, amongst others, are routinely exploited to achieve separations. The target minerals, which are embedded within a quartz or granite host rock or medium, must be released through breakage and ultimately grinding. This preparation produces a low portion of high value particles consisting of the target mineral, composite particles consisting of the mineral and unwanted host rock known as gangue, and a high proportion of unwanted gangue particles. The liberated minerals often exhibit a higher density and hence weight force at a given particle size, a basic property exploited in gravity separation. The liberated minerals of interest also associate with specific collectors, chemicals that yield strong hydrophobicity, in contrast to the unwanted gangue material that usually remains hydrophilic. Hydrophobic surfaces have an affinity for media other than water, such as air bubbles in froth flotation, and oils in agglomeration.

Program 1 consists of four sub-programs.

The first is concerned with establishing advanced forms of characterisation of mineral particles, and mineral surfaces, how to quantify the extent of mineral liberation, and the theoretical limits linking the maximum possible metal grade (wt%) to a given metal recovery (%).

The second is concerned with addressing the objective of achieving early-gangue rejection, through the establishment of relatively coarse particle separations to remove the unwanted gangue at a coarser grind size. Approaches using both froth flotation and dry separations will be investigated.

The third is focused on the separations required when the particles have been ground to a particle size sufficient for full liberation. There is substantial scope to fully exploit the potential of the hydrophobic effect to achieve a substantial increase in the speed of fine particle processing, by a factor of 10-100, including higher product grade, and recovery.

The fourth is concerned with the recovery of the process water, the goal being to reduce the ultrafine solids sent to the tailings stream and deliver the tailings at a concentration sufficient for stackable storage of the solids.

Research Program Leaders: Professor Karen Hapgood, Professor George Franks and Dr Liza Forbes

Minerals of high value are rendered hydrophobic through the specific adsorption of reagents known as collectors. This has been the predominant methodology for 100 years, generally achieved through flotation. However, there is a need for new approaches to advance selectivity, and to properly exploit the full-potential of hydrophobic interactions in effecting i) coarser separations, ii) ultrafast and selective separations, and iii) a step change in solid-liquid separation. For example, our recent work shows that a 10-100-fold increase in the process intensification can be realised, so we know there exists a tremendous upside via our strategy to further exploit hydrophobic interactions.

Program 2 investigates the application of novel hydrophobic interactions utilising bubbles, emulsions, and foams, and the selective promotion of hydrophobicity at the mineral surface to support more robust, faster and more efficient separation technologies. This research seeks to extend the conventional notion of flotation into a far broader concept. Hydrophobic interactions are powerful, can be made selective, and potentially support very fast separations.

The Program has three sub programs.

The first is related to understanding how novel polymers (developed in Program 3) can be applied to selectively and efficiently recover both coarse and fine particles by froth flotation and agglomeration. Such advances will reduce the degree of fine grinding required via the introduction of early gangue rejection and reduce the loss of fine valuable product to tailings.

The second seeks to develop novel systems to deliver reagents to the surfaces of particles in order to control their hydrophobicity for collection via flotation, or the ultrafast agglomeration in Program 1. The novel delivery systems will reduce the amount of reagent required and enable faster recovery of valuable particles, resulting in reduced processing costs.

The third will develop understanding of how the use of the polymers developed in Program 3, and the novel delivery systems developed in our second sub-program can be applied to improving solid liquid separations, to end the practice of using tailings dams.