They are invisible to the naked eye, able to withstand extreme conditions and capable of breathing rocks. They are the microbes that thrive in tailings ponds at mining sites around the world, and a team of Canadian researchers believes they are the key to transforming waste material into something much more valuable.

“There are bugs that thrive on metabolizing sulfur, others on metabolizing iron,” says Professor Vladimiros Papangelakis (ChemE). “If we can control such biochemical reactions, we could both remediate the waste and recover valuable metals that could pay for the cost of processing.”

Papangelakis, along with Professor Elizabeth Edwards (ChemE) is leading the Elements of Bio-mining project, a multidisciplinary collaboration between U of T Engineering, Laurentian University, and the University of British Columbia (UBC), as well as a number of technology, engineering and mining companies, including Glencore, Vale, Teck, Barrick and Hatch.

For a full list of team members and partners, visit the Elements of Bio-mining website

Together, the team is developing ways to process a number of different types of material left over from mining activities across Canada, from nickel mines in Sudbury, Ont. to coal mines in British Columbia. They aim to understand how native microorganisms at these sites convert chemicals one form to another, and how they might encourage certain beneficial reactions while discouraging others.

Members of the Elements of Bio-Mining project team at the In the Footsteps of Sudbury’s Minersexhibit at Science North in Sudbury, Ont. (Photo: Sean Caffrey)

For example, nickel refining produces tailings, which are rich iron sulfide. When exposed to the oxygen in the atmosphere, chemical reactions begin to convert the sulfides into sulphuric acid. This process — known as Acid Mine Drainage (AMD) — is catalyzed by microorganisms that live in the rainwater or melting snow that washes over the tailings.

The sulphuric acid can dissolve any nickel that remains in the tailings, as well as other metals such as copper and zinc and even toxic elements like arsenic, selenium, cadmium, mercury. Because of its toxic and acidic nature, tailings water cannot be discharged into the environment unless it is collected and treated. Currently, these tailings sit in enormous ponds around the mine sites — the water covers the tailings, acting as an oxygen barrier and slowing the AMD process.

Papangelakis and his collaborators hope to treat these tailings using bioreactors, vessels that enable them to control the temperature, pH, dissolved oxygen levels and other culture conditions. One idea is to encourage the growth of organisms that would convert the sulfide not into sulfuric acid, but into elemental sulfur, which may have some value if recovered. At the same time, the metal-rich wastewater could be captured and refined to recover metals, potentially providing a revenue source to offset the cost of treatment.

Other members of the team are looking at the waste rock that was separated before the refining process. Here sulfur is less of a problem, but there are still potentially valuable metals that could be recovered. Professor Nadia Mykytczuk of Laurentian University is studying ways to encourage bacteria to selectively dissolve these metals from heaps of rock, a process known as in-situ bio-leaching.

“There is a large diversity of organisms out there that we are only starting to understand,” says Mykytczuk. “Some of them like oxygen, but others thrive under anaerobic, or oxygen-free conditions. We’re looking at the whole range of possibilities, and once we find something promising, we can decide how to address specific types of waste.”

A third branch of the team is focusing on waste from coal mines, which is often high in selenium. Though a necessary nutrient in small amounts, too much selenium can be toxic to many forms of life; for example, it can interfere with the development of fish embryos, reducing the number of viable adults in the next generation.

“There are some microorganisms that can actually use selenate, the dissolved form of selenium, for energy,” says Professor Sue Baldwin of UBC, another one of the project partners. “They take the selenate and turn it into elemental selenium, which precipitates out as nanoparticles attached to the organism’s cells. In this form, it’s no longer dissolved and you can just filter it out of the water.”

Baldwin points out that selenium is just one of many pollutants that exist in waste from coal mining. And as with nickel mining, there may also be valuable metals or other materials that could be recovered through biochemical transformations.

Papangelakis says that there may be up to $7 billion dollars worth of nickel alone locked in the tailings from Sudbury’s mines. “The question is, can this value be recovered in a way that makes the treatment and remediation process economically viable?” he says.

In addition to the universities and the industrial partners, the project has attracted support from a number of research funding agencies, including the Natural Sciences and Engineering Research Council (NSERC), Genome British Columbia and Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). Most recently, the project received $4 million from the Ontario Research Fund.

“It’s a very challenging problem that needs to be solved,” says Papangelakis. “But we have assembled a very good knowledge base, with experienced people in mining, chemistry, biochemistry and process engineering. There will be cross-fertilization and new ideas, which will create a springboard to understand new science and launch initiatives we haven’t thought of yet. To me, this is the most exciting part.”

Every morning for a year, in the dead of winter or heat of summer, Marina Reny (Year 4 MinE) rose at 4:30 a.m., before sunrise, and prepared to board the bus that drove her through the boreal forests of northern Alberta on her way to work.

‪“Some mornings I would wake up to the northern lights, or drive past bears and moose on the way to the site.  Other days I would pass by flocks of migrating geese or sandhill cranes,” she recalls.

‪‪Reny spent her Professional Experience Year (PEY) 70 kilometres north of Fort McMurray, Alta. on a placement at Imperial Oil’s Kearl Oil Sands project — a location so remote that employees had to be flown in and out for work cycles lasting 10 days at a time. But coming from a relatively small town in B.C., the isolation appealed to Reny — it was part of what attracted her to the field of mining in the first place.

According to a recent report from the Mining Industry Human Resources Council, women make up 17 per cent of workers in the mining industry. At U of T Engineering women represent 27 per cent of current undergraduate enrolment in the Lassonde Mineral Engineering program, up 6 per cent over the previous year.

“After my first year in Engineering Science, I wanted to pursue other options. I did some background research, and I really liked the dynamism and remoteness of mining, as well as its geological aspects,” explains Reny. “Ever since then, I’ve been really happy and I haven’t looked back.”

Over the course of her studies in the program, Reny completed two internships with Imperial Oil, and will be returning to work with them in August after receiving a full-time job offer at the completion of her last placement.

“I was there for 12 months and then I came back again for another four months, so I actually had a chance to establish meaningful relationships,” says Reny. “In a four-month placement, it’s a little bit hard to make those deeper connections.”

During her PEY placement — a 12- to 16-month paid internship that embeds students within companies around the world to gain industry experience — Reny worked with the project’s Mine Operations team. Her position was focused on maximizing operating efficiency, which exposed her to all aspects of a large-scale mining operation.

While on-site, Reny was a regular member of the team and spent her 12-hour shifts speaking with operators, analyzing dispatch data, looking for inefficiencies and communicating her findings back to management.

“A lot of the inefficiencies were human factors, like breaks and shift changes,” she explains. Reny watched how various crews ran their shifts, and the most efficient practices she identified became standards. “Human factors are the ‘low-hanging fruit’ where you can really make gains with relatively minor changes,” she says.

Marina Reny stands next to one of the mining haul trucks used at the Kearl Oil Sands mine to transport oil. (Photo: Marina Reny)

After wrapping up her PEY internship, Reny completed one more semester of classes before returning to Imperial Oil for a summer internship. This time, she worked with their project development group in the Calgary head office. “It was such a great experience — having come from the actual mine, I got to see a whole other side of things. I got to see all their projects that they’re exploring for the next 10–20 years.”

At the end of her internship, Reny was offered a full-time position at Imperial’s head office in Calgary. She’ll be joining the Engineering department, where she’ll get to work on broader planning for the mine.

“Working in the mining industry, I realized that there’s actually a lot of opportunity for growth — especially technologically and in terms of sustainability,” Reny says. “I think the next couple of decades will be very interesting and I’m excited to be part of it.”