Researchers in Sudbury, Ont., are working on scaling up bacteria-powered technology in an effort to recover valuable metals from old mine waste.
A pilot facility operated by MIRARCO Mining Innovation is testing how microbes can break down mine tailings — the leftover rock and sediment from mining — and release critical minerals such as nickel, cobalt and copper in a process known as bioleaching.
Although bioleaching technology is a staple in international mining, in use at some 30 mine sites globally, Canada has yet to achieve full-scale commercial deployment, according to Nadia Mykytczuk, CEO of MIRARCO, the research arm of Laurentian University.
Mykytczuk was among those who spoke to CBC during a recent tour of the 10,000-square-foot pilot facility in Sudbury, including to get a first-hand look at how bioleaching works.
Although researchers moved into the facility last May, their work has been years in the making.
“Tailings are a very common material that you see here in Sudbury or any mining community,” said Mykytczuk. In Sudbury alone, the tailings contain $8 billion to $10 billion worth of nickel, she said.
Possible environmental risks
Despite the estimated value of the waste material, companies have yet to put money into reprocessing the tailings because of the significant cost of sending the material back to the smelter.
Instead, tailings are typically mixed with water and stored in large ponds — raising concerns about long-term environmental risks.
Jaime Kneen, national program co-lead with MiningWatch Canada, said there are two main risks: how the material behaves chemically and whether it remains physically stable over time.
One concern is that tailings can generate acid and release metals that may slowly leak into the surrounding environment.
To limit those reactions, tailings are often stored underwater. But that creates another risk, according to Kneen.
“Now you’ve got hundred of millions of tons of material that’s wet and not stable and has to be held back by a dam, which has to be intact for centuries, if not millennia, to keep that stuff from crashing down on the rest of the landscape or being washed away in a flood,” he said.
Kneen highlighted the potential consequences if these structures fail, citing the 2014 collapse of the Mount Polley mine tailing dam in British Columbia that caused the release of toxic mine waste into adjacent lakes and streams.
If those structures fail, the consequences could be severe, Kneen said. He pointed to the 2014 failure of the Mount Polley mine tailing dam in British Columbia that led to toxic mine waste entering nearby lakes and streams.
Call for more critical mineral development
Both the federal and provincial governments have significantly intensified calls for critical mineral development to secure supply chains for clean energy technologies — like EV batteries — and national defence due to rising global demands and the need to reduce reliance on adversarial suppliers.
Mykytczuk said bioleaching is a way to tackle both the demand for critical minerals and mining cleanup.
“If we want to find a source of the critical minerals in the near term, the mine waste are a fantastic opportunity. There’s potential to extract billions of dollars worth of these critical minerals in a very short time frame.
“We want to make sure these technologies get into the hands of industry. So we need to build larger spaces like this [Sudbury facility] to scale that up.”
Similar work is underway elsewhere in Canada, though much of it remains in its early stages.
In Nunavut, Canadian North Resources has tested bioleaching at its Ferguson Lake project; in northern Alberta, an exploration company is studying whether microbes could help extract rare earth elements from black shale.
The Sudbury project is among several receiving support through the federal Critical Minerals Research, Development and Demonstration program, aimed at moving technologies like this closer to commercial use.
How bioleaching works
The bioleaching process starts by grinding down tailings and mixing them with a liquid solution that feeds the bacteria. That’s also when the microbes are introduced into the mixture.
As the bacteria feed on the minerals, chemical reactions allow the metals to separate and move into the liquid.
The resulting slurry is then moved through a series of reactors, where the process continues. The metal, which is now in a liquid form, is then extracted.
Researchers inside the lab are working to replicate how the process would function in a large mining operation.
That means designing a system in which material moves continuously through a series of tanks, rather than being processed in separate batches, explained Emmanuel Ngoma, a senior scientist at MIRARCO.
Ngoma said the setup allows the slurry to flow from one stage to the next — often using gravity — while fresh material is constantly added at the start.
“In the mining industry, you do not work on a batch system. You always continuously supply fresh material.”
Once the process is complete, most of the metal contained inside the tailings can be extracted.
“I can recover about 98, 99 per cent of the nickel that was put through at the end of this process. And this in terms of research is good…. It’s actually worth increasing the capacity and investing into a much bigger system,” Ngoma said.
(Ezra Belotte-Cousineau/Radio-Canada)
Waste is still left behind after the process is complete, but Ngoma said it’s “free from toxic material and can be used for other things.”
The remaining material could potentially be reused in construction or returned underground as backfill in mining operations, he added.
Growing the bacteria
In another lab in the Sudbury facility, Zach Diloreto, a senior research associate, explained how the team develops the bacteria used in bioleaching.
“In these cultures, we grow up the bacteria that do the work,” Diloreto said, adding that different types of microbes are designed to target specific minerals found in mine waste.
Some of those microbes are acid-loving, meaning they thrive in highly acidic conditions. They’re used to break down sulfide tailings, a common type of mine waste.
Others are tailored to go after different materials, including iron oxides and silicate minerals, which can contain valuable elements used in modern technology.
Those include rare earth elements and metals like lithium, dysprosium and neodymium, which are key components in electric vehicle batteries and clean energy systems, for example.
“We use high precision analysis, geochemical, biogeochemical, and we look at different strategies to effectively and economically extract things like rare earths from different mineral host rocks,” Diloreto explained.
To study how well the process works, researchers analyze how the bacteria interact with different types of rock. One example is spodumene, a mineral commonly found in the Sudbury region that naturally contains lithium.
Diloreto said most lithium extraction today relies on processes that can be energy intensive.
“In today’s day and age, most [lithium extraction] is done at high temperature, high pressure. But we can look at things like specialized organic acids and biomolecules produced by specific bacteria to target these minerals.”
The next steps
The team is also exploring ways to turn the extracted metals into products with industrial applications.
Diloreto said part of his job is to prove to industrial partners that the materials they process are commercially viable and more valuable than a standard material like iron.
For example, he can convert a basic iron resource into a ferrofluid, which can be used for things like water purification.
The research team said the next step is to move from pilot testing to full-scale operations in Canada, hopefully within the next two to three years.
“There are commercial examples globally already. Canada has yet to build a full-scale commercial bioleaching operation, but we’re getting really close,” Mykytczuk said.
