JOHANNESBURG (miningweekly.com) – Using bacteria to extract minerals from ore is showing the potential to replace dangerous processing chemicals such as cyanide in the mining industry.
Scientists at Flinders University, in South Australia, are developing a growing line-up of lab-based experiments to extract valuable minerals from ore using environment-friendly microbes commonly found on mine locations.
Associate Professor Sarah Harmer said the next stage of the new technique, called bioflotation, would involve scaling up to larger and more complicated experiments.
“We’re making real progress in finding better ways to more sustainably separate valuable ores such as copper, iron, lead and zinc,” she said.
“At the moment we’re mixing together pure minerals of known quantities and purity and studying the effects.
“We’re trying to pin down what exact chemicals the bacteria are giving out that are helping modify surface properties. Once we know what those chemicals are we might be able to just use those rather than having to use the bacteria itself; then that would be a much simpler system to use.”
Harmer said making the technology cost effective on a large scale for commercial use in the mining industry would be crucial.
“That’s what has really slowed the adaption of using microbes and different types of bacteria for minerals processing. They’ve only been done on a small scale in the past due to the cost,” she said.
“It’s what they (mining companies) consider blue sky research so we need to upscale a little bit more before we actually do it together and that’s the next step.
“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.”
Toxic byproducts from mining and ore processing continue to plague the mining industry – and the environment.
Every year large volumes of heavy metals and toxic chemicals leach into soil, groundwater and rivers from mining company operations.
For the first time, Harmer’s team at Flinders University School of Chemical and Physical Sciences has used high-tech X-ray imaging and micro-spectroscopic methods at synchrotrons overseas to study the distribution of chemical species responsible for the selective attachment of bacteria and the separation of minerals.
They also have used the extreme light beams of the Australian Synchrotron and synchrotrons overseas to identify the chemical mechanisms of bioleaching of chalcopyrite, or copper ore, using soft and hard X-ray spectroscopies.
South Australia’s capital, Adelaide, has three long-standing public universities, Flinders University, University of South Australia, and the University of Adelaide, each of which is consistently rated highly in the international higher education rankings.