Researchers from the University of Toronto – in collaboration with a group of mining firms – are using acid-loving bacteria to design new processes for recovering nickel, a critical mineral in growing demand around the world.
The research partnership with the Faculty of Applied Science & Engineering includes the following companies: Vale, Glencore, Metso-Outotec, BacTech, MIRARCO and Yakum Consulting. The insights gained could enable these companies to reduce their environmental footprint while at the same time gaining access to new sources of nickel, which is used in everything from stainless steel to next-generation batteries for electric vehicles.
The project is supported by $2 million in funding through Ontario Genomics from Genome Canada. The industrial partners will also provide approximately $2 million in funding and in-kind contributions.
“Tailings from nickel mining operations have been an environmental challenge for a very long time,” says Radhakrishnan Mahadevan, a professor in the department of chemical engineering and applied chemistry who is leading the new partnership.
“If exposed to oxygen, chemical reactions in the tailings generate acids that makes them toxic to most forms of life. But we know that there are some microbes that can thrive in these environments. The biochemical techniques they use to survive can offer us new pathways to meet our goals.”
In Canada, nickel is found in ores that are mostly composed of iron and sulphur. After most of the nickel is extracted, the iron and sulphur remain, along with trace amounts of nickel – typically less than 1 per cent by weight. Together, these substances are known as tailings, and they exit the extraction process in the form of a slurry, a suspension of tiny mineral particles in water.
If the slurry is exposed to oxygen, the sulphur remaining in the slurry can become oxidized to form sulphate, a key component of sulphuric acid. To slow this process, the tailings are typically stored under water in tailings ponds. However, over time, these ponds still become highly acidic, with a pH in the range of 1-2.
Mahadevan, University Professor Elizabeth Edwards and Professor Vladimiros Papangelakis – all in the department of chemical engineering and applied chemistry – have been studying the organisms that are able to survive in these tailings ponds.
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