Understanding the mining microbiome might be the Midas touch when it comes to a better way to extract gold from tailings.
The lure of gold has a rich history in Canada. Now, scientists at the Research & Productivity Council (RPC) in Fredericton, New Brunswick are working with Genome Atlantic on an innovative new twist to extracting gold from tailings.
The current bio-leaching approach uses bacteria to help oxidize sulphide minerals within tailings, which makes it easier to leach out the gold. While this process has been around for a while, scientists at RPC are introducing a novel element – genomics, which is the powerful combination of genetics, biology and computer science.
“Bioleaching and bio-oxidation have been used in the mining industry before but they’re passive biological processes known to have slow reaction rates,” says Neri Botha, an extractive metallurgist at RPC. “Our project is focused on utilizing indigenous bacteria and improving the process through genomics. Basically, we are using genomics to read the DNA of the bacteria at play.”
Essentially, RPC is looking at the naturally-occurring microbiome that exists on the tailings site. While the microbiome is often associated with human health, single celled organisms that make up the microbiome are also found in the natural environment, including in soil, water and plants.
“It could represent a real upgrade from the traditional bio-oxidation/bio-leaching process.” – Leo Cheung
The Minerals and Industrial Services team at RPC is working with a private Canadian mining company on a research project funded by Genome Atlantic to determine what ‘bugs’ make up the microbial community, how they work, and what factors (like temperature or pH levels) influence their productivity. With this new information, the team hopes to reduce the time and resulting costs of this passive gold oxidation method. RPC is highly experienced to conduct this research, having conducted many types of bioleaching tests for clients around the world.
The project is based in Atlantic Canada on an old tailing site, which opens up opportunities for other legacy sites that have been abandoned due to the effort and cost of further extraction. If this biological approach can be optimized with genomic data, the effectiveness could make the ROI more attractive.
Leo Cheung, the department head at RPC, says that there could be a substantial amount of gold in the tailings tested (an estimated 1 gram per ton) – so there is much to be gained from the new genomics-based process. “It could represent a real upgrade from the traditional bio-oxidation/bio-leaching process.”
In addition to the potential enhanced return on investment, the reduced need for chemicals such as cyanide, which is traditionally used for leaching, can be another benefit. This unique marriage of biology and technology may be an important tool to keep Canada in the top five gold-producing countries in the world.
“Employing genomics to leverage bacteria usage in mining has many potential applications. Bioleaching is already used in the extraction of other metals like nickel, cobalt, copper and zinc, so genomics could make those processes more effective. Also, genomics is used successfully in many other industries. Clearly, there is a large scope for more research to be done,” says Cheung.
In June 2016, Botha shared the team’s research at the Mining Society of Nova Scotia’s annual meeting in Halifax. Since then, the project has continued to progress well and the team hopes to soon identify the specific bacteria which can be used to improve oxidation.
