For the first time a new technique will attempt to extract low-grade copper in an affordable and sustainable way to extend the life of some of the world’s largest and oldest mines.
The research, funded by a new three-year $785,000 Australian Research Council (ARC) Linkage grant, will be led by Flinders University with industry partner BHP Billiton. The project will focus on exploiting a normal ore body process known as supergene enrichment, says Flinders University Professor of Chemical Minerology Dr Allan Pring.
“This groundwater process happens naturally in the top parts of many copper deposits and converts primary copper sulfide minerals, which are expensive to mine and treat, into copper metal,” says Professor Pring. “This means low-grade ore is naturally upgraded into high-grade deposits.”
This process has been seen at the historically important copper deposits in South Australia, including Burra, Kapunda and Moonta which helped to establish the State’s economy in the 19th century.
“Before we can adopt that process in a large or commercial way, we have to understand the chemistry of these reactions,” adds Professor Pring. “And this can only be done by extensive laboratory experiments using special flow-through equipment my research group has developed at Flinders.”
Professor Robert Saint, Deputy Vice-Chancellor (Research) at Flinders, says the latest ARC Linkage research builds on exciting fundamental and applied scientific research underway at the University.
“Researchers at Flinders are capitalising on emerging and traditional technologies to find new and more environmentally friendly ways to benefit a range of industries,” says Professor Saint. “For example, several Chemical and Physical Sciences projects are making great inroads using the latest in microscopy and synchrotron X-ray spectromicroscopy to create future solutions for mining and other sectors.”
The Flinders researchers, including Associate Professor Sarah Harmer, Dr Christopher Gibson and postgraduate students, will collaborate with leading minerology reseachers Professor Joel Brugger (Monash University) and Dr Benjamin Grguric (South Australian Museum), along with BHP Billiton principal geometallurgist Dr Kathy Ehrig.
“We are not setting out to improve the recovery of copper by a few percentage points,” says Associate Professor Harmer. “We are aiming to provide a new and innovative approach to the problem.”
Associate Professor Harmer is an ARC Future Fellow Associate, and is studying the interaction between bacteria and mineral surfaces using advanced synchrotron spectromicroscopy techniques. She says the new ARC project is strategic but with a definite applied outcome in mind.
Supergene zones occur at the top of ore deposits and just below the water table.
“Mild oxidazing reactions take place causing the primary ore minerals, such as chalcopyrite, to be replaced by more copper-rich, less refractory minerals,” says Associate Professor Harmer. “These processes are driven by coupled dissolution-reprecipitation (CDR) reactions and in many CDR reactions, the reaction mechanism, rather than intensive properties such as pressure and temperature, control the nature of the products and the overall reaction process.
“This project will explore the mechanism and controls on these reactions to see if they can be utilised in the mining industry to economically extract copper from low grade ores.”
This not only would extend the life of jobs and infrastructure at remote mine sites but reduce spending on the development of new mine sites. The Australian Government has provided $485,000 in funding for the project through the Australian Research Council’s Linkage Projects scheme. Matching cash and in-kind contributions are provided by the industry partner. Flinders University researchers are also involved in the 2016-2020 ARC Research Hub for Australian Copper-Uranium project.