Researchers in Sudbury, Ontario, are currently engaged in efforts to advance bacteria-powered technology to extract valuable metals from old mine waste on a larger scale. The pilot facility, managed by MIRARCO Mining Innovation, is conducting experiments to evaluate how microbes can decompose mine tailings, which are the residual rock and sediment from mining activities, to release essential minerals such as nickel, cobalt, and copper through a process known as bioleaching.
Although bioleaching technology is commonly used in international mining operations, with around 30 mine sites globally employing this method, Canada has not yet achieved full-scale commercial implementation, as mentioned by Nadia Mykytczuk, the CEO of MIRARCO, the research division of Laurentian University. Mykytczuk recently spoke to CBC during a tour of the 10,000-square-foot pilot facility in Sudbury to provide insight into the workings of bioleaching.
Despite the significant value of the waste material, companies have hesitated to invest in reprocessing the tailings due to the substantial expense involved in transporting the material back to the smelter. Instead, tailings are commonly mixed with water and stored in large ponds, raising concerns about potential long-term environmental hazards.
Jaime Kneen, national program co-lead at MiningWatch Canada, highlighted two primary risks associated with tailings management: the chemical behavior of the material and its long-term physical stability. The potential environmental risks include the generation of acid by the tailings and the release of metals that could gradually seep into the surrounding environment. To mitigate these risks, tailings are often submerged in water. However, this creates a new concern, as large quantities of wet and unstable material must be contained by a dam, which needs to remain intact for centuries to prevent environmental disasters.
The push for critical mineral development has intensified at both the federal and provincial levels to secure supply chains for clean energy technologies, such as electric vehicle batteries, and national defense in response to growing global demands and the necessity to reduce reliance on potentially adversarial suppliers. Mykytczuk emphasized that bioleaching offers a dual solution by addressing the demand for critical minerals and aiding in mining cleanup efforts.
Mykytczuk stressed the importance of transferring these technologies to the industry, emphasizing the need to establish larger facilities akin to the one in Sudbury to scale up the process. Similar initiatives are underway in other parts of Canada, although many are still in the early stages of development.
The bioleaching process commences with the grinding of tailings, followed by their mixing with a liquid solution that nourishes the bacteria responsible for the breakdown. As the bacteria consume the minerals, chemical reactions facilitate the separation of metals, allowing them to dissolve into the liquid. The resulting slurry is then circulated through a series of reactors to extract the metals in liquid form.
Researchers are actively working to replicate this process on a larger scale for practical implementation in mining operations. This involves designing a continuous material flow system through interconnected tanks, as opposed to separate batch processing, as explained by Emmanuel Ngoma, a senior scientist at MIRARCO.
While some waste remains after the bioleaching process, Ngoma assured that it is free from toxic substances and can potentially be repurposed for construction or utilized as backfill in mining operations. The team is also exploring methods to convert the extracted metals into valuable industrial products.
In a separate lab within the Sudbury facility, Zach Diloreto, a senior research associate, elaborated on the cultivation of bacteria essential for bioleaching. Different strains of bacteria are cultured to target specific minerals present in mine waste, with some strains thriving in highly acidic conditions to break down sulfide tailings. The team is focused on extracting valuable elements like rare earth metals and lithium used in modern technologies.
Moving forward, the team aims to transition from pilot testing to full-scale operations in Canada within the next two to three years. Mykytczuk expressed confidence that Canada is on the brink of establishing a full-scale commercial bioleaching operation, following successful global precedents.
