OBJECTIVES

The use of solvent extraction (SX) in the minerals industry has numerous advantages: it can be used for a wide range of metal ions and over a broad range of pH values; it enables complete separation of chemically similar metals (eg nickel and cobalt) and it allows simultaneous separation/concentration of metals from both dilute and concentrated solutions, making it particularly useful in the processing of low-grade ores.

However, a major drawback is that SX is generally undertaken in mixer-settlers which use mechanical agitation for mixing. Mixer-settler contactors have some inherent shortcomings that can impact on the SX process and also on downstream operations such as electrowinning. For example, the intensity of agitation can cause problems: insufficient mixing reduces the efficiency while excessive mixing can result in high shear and poor separation of the organic and aqueous phases. Operating costs are high because mechanical agitation requires a considerable power input and maintenance of the moving parts can be costly.

Therefore, there is a need to develop alternative contactors for industrial use. This project is investigating electrostatically agitated SX which uses an electrostatic field to disperse the aqueous phase into the organic phase. A number of studies, including previous work undertaken by the project team on electrostatic pseudo liquid membrane, have shown that electrostatic SX has the potential to combine the advantages of conventional SX and electrostatic agitation.

Since fundamental understanding of electrostatic SX is limited and no application in hydrometallurgy has been commercialised, the objectives of this project include:

• investigating the fundamentals of electrostatically-induced dispersion and dispersed phase motion in electrostatic SX
  
• studying mass transfer in electrostatic SX
  
• developing and assessing an electrostatic SX contactor.

INDUSTRY BENEFITS

• an alternative solvent extraction contactor that utilises electrostatic dispersion, which leads to high mass transfer of the desired metal ions – without moving parts – and has other advantages over the mixer-settler contactors currently used in industry.

RESEARCH TEAM
Associate Professor Don Ibana (Project Leader)
Mr Joel Collard (PhD student)
Mr Marc Steffens (PhD student)
(Curtin University - WA School of Mines)

PROJECT DURATION
2006-2009