Flotation of fine minerals: Novel temperature responsive polymer as flocculant and collector

Project description

Froth flotation is an efficient method for selectively recovering valuable mineral particles in the range 50 to 200 microns, but low collection efficiency is observed for fine particles < 50 microns. Conventional flotation reagents are typically low molecular weight surfactants. These molecules specifically adsorb to the valuable mineral, rendering it hydrophobic. The low molecular weight surfactants are not good at aggregating fine particles and as such they are not collected. It would be of significant financial advantage to be able to recover fine minerals for sale, especially as the increasing reliance on low grade ores requires additional grinding in order to liberate the valuable mineral. The Franks group at the University of Melbourne has developed temperature responsive flocculants based on poly (N-isopropyl acrylamide) (PNIPAM) over the past several years.1-3 In addition to aggregating the fine primary particles into aggregates with optimum size suited for flotation, the surface of the particles is rendered hydrophobic, so the aggregates can be collected by flotation.4-7 The aim of this PhD project is to investigate the techno-economic implications of using temperature responsive polymers as flotation reagents. Specifically evaluation of how to incorporate the new technology into existing mineral processing plants and the influence of the new processing steps on the economics of the operation will be investigated. Processes to be investigated include copper ores, iron ore, phosphate ores and other operations.

Students with degrees in Minerals Processing or Chemical Engineering are encouraged to apply, especially those with experience in flotation or flocculation.   

For technical information on the project, contact the academic supervisor, Prof. George V. Franks, gvfranks@unimelb.edu.au.

1) G. V. Franks, “Improved Solid/Liquid Separation using Stimulant Sensitive Flocculation and Consolidation”, Journal of Colloid and Interface Science,292, 598-603 (2005). 

2) H. Li, J.-P. O’Shea and G. V. Franks, “Effect of Molecular Weight of Poly(N-isopropylacrylamide) Temperature-Sensitive Flocculants on Dewatering”, AIChE Journal, 55 [8] 2070-2080 (2009).

3) J.-P. O’Shea, G. G. Qiao and G. V. Franks, “Solid-liquid separations with a temperature-responsive polymeric flocculant: effect of temperature and molecular weight on polymer adsorption and deposition”. Journal of Colloid and Interface Science, 348, 9-23 (2010).

4) Burdukova, H. Li, N. Ishida, J.-P. O'Shea and G. V. Franks, “Temperature Controlled Surface Hydrophobicity and Interaction Forces Induced by Poly (N-Isopropylacrylamide)”, Journal of Colloid and Interface Science, 342, 586-592 (2010).

5) G. V. Franks, H. Li, J.-P. O’Shea and G. Qiao, “Temperature responsive polymers as multiple function reagents in mineral processing”, Advanced Powder Technology, 20, 273-279, (2009).

6) W. S. Ng, R. Sonsie, E. Forbes, G. V. Franks, "Flocculation/flotation of hematite fines wiht anionic temperature responsive polymer acting as selective flocculant and collector", Minerals Engineering, 77, 64-71 (2015).

7) W.S. Ng, L. A. connal, E. Forbes, G. V. Franks, "Xanthate-functional temperature responsive polymers as selective flocculants and collectors for fines recovery", Minerals Engineering, 97, 73-82 (2016).

Project team

Leader: George Franks

Other projects

Optimisation of resources and infrastructure projects

Research Centre

Particulate Fluids Processing Centre (PFPC)


Chemical &amp; Biomolecular Engineering


Optimisation of resources and infrastructure


stimulant responsive polymers