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IWRI Background

Problem Description

 - Phenomena

 - References

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IWRI Background

The Ian Wark Research Institute (IWRI) is located at Mawson Lakes in Adelaide, South Australia, twelve kilometres north of the city centre. Named in honour of the pioneering minerals scientist, Sir Ian Wark, the Institute was founded in 1994 with Professor John Ralston as Director. It is one of the key research concentrations in the University of South Australia. The IWRI is the Australian Research Council Special Research Centre for Particle and Material Interfaces. It performs a special blend of fundamental and applied research. Its research is published in respected international journals and may appear as patents. Some of the IWRI research work is aimed at improving existing processes in industry whilst other efforts lead to new technologies. The links between the IWRI and industry are excellent, both nationally and internationally.

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Problem Description

The use of column flotation to separate metallic particles from the original heterogeneous ores is a well-established and widely used procedure.  The column consists of two basic zones – the froth layer on top and the pulp layer below.  Although some useful models have been developed to describe the capture and transport of material in the pulp [1] the principal quantitative mechanisms that describe particle transport and fluid flow within the foam have not been successfully modelled.

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Phenomena

Jameson [2] believes it would be useful to find quantitative descriptions for some or all of the following phenomena; 

• the entrainment of liquid and particles from the pulp into the froth;
• the relationship between the liquid fraction in the pulp and the liquid fraction in the froth immediately above the pulp;
• simultaneous upward flow of liquid to the cell product lip and downward flow of liquid to the pulp in the froth layer;
• the effect of entrained particles on froth drainage and on liquid transport to the lip;
• the changing shapes of bubbles as they rise through the froth and the consequent change in shape of the liquid films between the bubbles;
• the effect of the floatable particles attached to the bubbles on flow in the thin liquid films;
• coalescence and bubbles coarsening in the rising froth and the effect of hydrophilic and hydrophobic particles;
• the effect of all particle types on foam rheology;
• the rate of release of gas into the atmosphere from bubbles that burst at the top surface of the froth;
• dispersion of hydrophobic particles in the liquid films when bubbles coalesce in the rising froth and the probability of re-attachment; and
• forces of attraction between hydrophobic particles and bubbles in the froth zone;
• collection efficiency of particles in the froth zone.

IWRI would like to develop basic quantitative descriptions of particle transport and fluid flow in the froth layer without resorting to a full computational fluid dynamics model.  It has been suggested that the theory of flow through a porous medium may be relevant.

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References

[1]     Pyke, B., Duan, J., Fornasiero, D., and Ralston, J., From turbulence and collision to attachment and detachment: A general flotation model, In: Proceedings “Flotation and Flocculation – From Fundamentals to Applications”, Kona, Hawaii, 2002. ISBN 0-9581414-0-1.

[2]  Jameson, G. The froth phase in column flotation, In: Proceedings “Flotation and Flocculation – From Fundamentals to Applications”, Kona, Hawaii, 2002. ISBN 0-9581414-0-1.

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