OBJECTIVES

While thiosulfate is an alternative to cyanide for leaching gold from gold ores and concentrates, it is unlikely that a future viable thiosulfate leaching process would universally replace the robust cyanide process. However there are niche applications where thiosulfate offers significant advantages over cyanide.

A thiosulfate process could be useful in environmentally sensitive areas or close to major population centres, or for intensive leaching of small masses. Other potential applications include heap leaching and processing gold ores that are difficult to leach with cyanide such as preg-robbing ores and high copper ores. Another opportunity is to use thiosulfate for in situ leaching by pumping a thiosulfate solution underground to leach paleochannel gold present in porous sandstones that abut impermeable beds, and then bringing that solution back to the surface to recover the gold.

This project’s objectives are to:

• identify an environmentally acceptable process using thiosulfate for gold processing by heap and/or in situ leaching
  
• develop a flowsheet for the thiosulfate leaching of gold from complex ores
  
• identify improved processes for recovering gold thiosulfate from thiosulfate solutions or from resins since the gold thiosulfate complex does not adsorb to activated carbon.

INDUSTRY BENEFITS

• access to a resource that is uneconomic with present technology: achieved by in situ thiosulfate leaching of paleochannel gold
  
• a non-cyanide based process for recovering gold that could be used in environmentally sensitive areas or to treat ores that are not amenable to recovery by cyanide.

RESEARCH TEAM
Dr Matthew Jeffrey (Project Leader)
Dr Paul Breuer
Mr Karl Bunney
Ms Danielle Hewitt
Dr Vishnu Pareek
Dr Hongguang Zhang
Mr Abrar Muslim (PhD student)
Mr El-Sayed Oraby (PhD student

RESEARCH COLLABORATION
CSIRO Minerals
Curtin University
Griffith University

PROJECT DURATION
2005-2008