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Flotation

Flotation Cells

Background

Flotation takes place within flotation cells which broadly include mechanical, column, jet, film and novel flotation cells. Research in flotation cells is ‘themed’ into research into conventional mechanical flotation cells and novel flotation cells. These two areas have a common ‘cross-cutting research theme’ of investigating particle-bubble contacting in turbulent multi-phase flow environments, with the emphasis on fine particles. Fine particles appear to require more energy/turbulence for successful collision and often result in rheologically complex slurries. In addition, research in these two areas requires the use of computational methods for modelling fluid flow and an understanding of non-Newtonian slurry rheology. The primary objective of this research is to develop a kinetic model for describing the effect of energy/power on flotation in agitated systems.

Research Themes

Mechanical Flotation Cells: Research focuses on understanding the effect of agitation on hydrodynamics, solids suspension and gas dispersion in these conventional stirred systems. Here, the emphasis is on understanding the effect of non-Newtonian slurry rheology on hydrodynamics and gas dispersion. This is due to developments in ultrafine grinding, which results in some slurries developing pseudo-plastic behaviour, particularly those containing problematic minerals such as certain phyllosilicates.

Novel Flotation Cells: Research focuses on investigating the effect of energy/agitation on particle-bubble contacting in different types of turbulent multi-phase flow environments. These include i) conventional stirred cell - stirred flow field characterised by high levels of both convective and free turbulent flows ii) oscillatory baffled column - oscillatory flow field characterised by high levels of oscillatory convective flow and low levels of free turbulent flow and iii) oscillating grid cell - turbulent flow field characterised by minimal convective flow and high levels of homogeneous, isotropic free turbulent flow.

Activities Supporting Research Themes


Computational Methods: Computational Fluid Dynamics is used primarily as a research tool/aid for predicting flow fields which can then be used to understand the nature of particle-bubble contacting in these systems. Computational Fluid Dynamics coupled to the Discrete Element Method (CFD-DEM) is used for numerically investigating the effect of particle properties on slurry rheology.

Slurry Rheology: Research in rheology is primarily in the area of phyllosilicate minerals and their effect on non-Newtonian slurry rheology. Phyllosilicates are minerals which are known to cause problematic slurry rheology at relatively low solids concentrations, especially at fine particle sizes.