Scientists at Flinders University in South Australia are developing new processing methods to help miners eliminate widespread environmental damage caused by toxic chemicals and acid leaching.
The series of lab-based experiments help to extract valuable minerals from ore using environmentally friendly microbes such as bacteria commonly found on mine locations.
Flinders University associate professor Sarah Harmer said: “We’re making real progress in finding better ways to more sustainably separate valuable ores such as copper, iron, lead and zinc.
“This has the potential to be scaled up to one day replace toxic chemicals such as cyanide and xanthates now used to separate the minerals from ore in the early froth flotation phase of processing.”
During the process, waste rock and chemicals left behind will be saved in large tailing dams.
Harmer’s team at Flinders School of Chemical and Physical Sciences has used x-ray imaging and micro-spectroscopic methods at synchrotrons overseas to study the distribution of chemical species responsible for the attachment of bacteria and minerals’ separation.
Extreme light beams of the Australian Synchotron and synchrotrons were also used to identify the chemical mechanisms of bioleaching of chalcopyrite, or copper ore, with the help of soft and hard x-ray spectroscopies.
Harmer further added: “The capability for microscale spectroscopic analysis of materials while in liquid under controlled electro-chemical conditions is helping to confirm which bacteria attach to specific mineral surfaces for the application of mineral leaching and separation of minerals without the use of toxic chemicals.”
Mining companies are expected to scale up the small-scale experiments in trials in order to extract ores sustainably.
This will reduce the toxicity of tailing dams on mine sites, as well as challenges of environmental remediation of mine sites worldwide.
Image: Flinders University associate professor Sarah Harmer (centre) with postgraduate students Zoe Pettifer, Sian La Vars, Simon Lee, Belinda Bleeze and Connor Retallick at the Microbe Factory Laboratory. Photo: courtesy of Flinders University.