OBJECTIVES

Chemolithotrophic cells (used for bioleaching) catalyse the biooxidation process by oxidising iron(II) to iron(III) and creating a microcosm on the target sulfide mineral surface. Optimising the biooxidation process requires maximising the cell growth rate and the rate at which those cells oxidise iron(II).

A method developed in previous work had been used to quantify cell growth rate as a function of common contaminants in the process water used in biooxidation systems (eg chloride, sodium and sulfate ions). This enables evaluation of the effect of the quality of the process water (determined by the water composition) on biooxidation.

This project aims to extend the previous research on chemolithotrophic cell cultures by:

• measuring the inhibition of cell growth and iron oxidation due to other process water contaminants (eg gangue components, products of mineral oxidation and organics leaking from the cells) and changes in their concentration during biooxidation
  
• describing and measuring interactions between cells and mineral surfaces, and determining the effect of water quality on the crucial attachment of cells to the target mineral surface
  
• developing methods to collect and examine the structure(s) and rate of production of the solid iron oxide phases whose formation is also catalysed by biooxidation cell cultures.

INDUSTRY BENEFITS

• the potential to improve biooxidation process performance in industry through assessment of the response of chemolithotrophic microorganisms (used for bioleaching) to the presence in the biooxidation process water of specific ions of interest to clients
  
• the ability to provide reliable cost-benefit analyses of the effects of process water of varying quality and different treatment options on biooxidation in operating industrial bioleaching plants.

RESEARCH TEAM
Dr David Ralph (Project Leader)
Dr Kyle Blight
Mr Ragat Hans
(Murdoch University)

RESEARCH COLLABORATION
Hydromet Innovations
Korea Institute of Geoscience and Mineral Resources (KIGAM)

PROJECT DURATION
2005-2008