Chemistry of Novel Hydrophobic and Selective Interactions

TITLE LEADER & KEY PERSONNEL PROJECT SUMMARIES

P2.1 Flotation Collectors

33 Application of oils to enhance adhesion contact with coarse particles exhibiting low surface liberation

Leader: Prof David Beattie (UniSA)

Key Personnel:

Prof George Franks (UoM)

A/Prof Marta Krasowska (UniSA)

Prof San H. Thang (Monash)

The objective of this project is to improve the recovery of coarse particles with low surface energy in flotation by utilising oils and other chemicals. The adsorption of surfactants was investigated by the quartz crystal microbalance (QCM) for their use in the surfactant-induced spreading of the oil on a given mineral. These experiments were performed in aqueous solution using a novel surfactant designed and synthesised at Monash. The work will be extended to studying adsorption from oil.

35 Wetting, spreading, and adhesion of oils on composite mineral surfaces

Leader:

A/Prof Marta Krasowska (UniSA)

Key Personnel:

Prof Erica Wanless (UON)

Prof David Beattie (UniSA)

The flotation of composite particles at a coarse size requires new ways of attaching collectors to the particle surface. The use of oil is being investigated. Work has been focused on proof-of-concept for the spreading of droplets on heterogeneous surfaces. In addition, a study on varying interfacial tension of oil mixtures has been undertaken, as a prelude to using oil phase variation, to ensure droplet attachment to minerals of different hydrophobicity.

34 Application of oils to enhance flotation collection with coarse particles exhibiting low surface liberation

Leader: Prof David Beattie (UniSA)

Key Personnel:

Prof George Franks (UOM)

A/Prof Marta Krasowska (UniSA)

Prof San H. Thang (Monash)

PhD Student: Azeez Aregbe (UOM)

New collectors are needed for coarse particle flotation where the extent of valuable mineral liberation is poor. Emulsions have been developed incorporating conventional collector molecules as well as novel surfactants developed in the Centre. The emulsions have been characterised in terms of creaming rate, zeta potential and droplet size measurement. Initial contact angle measurements using a captive droplet technique indicate that the choice of surfactant combination can control wetting and spreading on chalcopyrite and quartz surfaces. The work has the potential to reduce energy used in grinding by allowing separation at a coarser size.

36 Application of synthetic and biopolymers in selective recovery of minerals

Leader: Prof David Beattie (UniSA)

Key Personnel:

Prof George Franks (UOM)

Prof San H. Thang (Monash)

Prof Chun-Xia Zhao (UoA)

A/Prof Marta Krasowska (UniSA)

This project focuses on the development of novel sensing surfaces employing an actual mineral for use in the quartz crystal microbalance (QCM). These experiments involved careful attachment of layered graphite to an underlying gold substrate, enabling direct gravimetric adsorption characterisation of the reagents onto the cleaved hydrophobic surface of graphite for the first time. This approach will be used to characterise the adsorption of novel polymers developed at Monash and UniSA.

37 Ultrafine particle deposition and adhesion with permeable hydrophobic surfaces

Leader: Prof Grant Webber (UON)

Key Personnel:

Dr Susana Brito e Abreu (UQ)

Ultrafine particles may be recovered via interactions with permeable hydrophobic surfaces and interfaces. This project seeks to develop an emulsion binder from renewable materials. Emulsions have been prepared using water and sunflower oil, with corn starch, cellulose or fly ash particle stabilisers. A range of oil:water ratios and added stabiliser concentration have been evaluated with the aim of producing a stable high internal phase water-in-oil emulsion. Corn starch has proven the most promising stabiliser, resulting in stable emulsions across a broad spread of compositions, although only stable oil-in-water and not water-in-oil emulsions have been produced.