Getting More from Mining Waste with Microbes

Researchers have developed a new mining technique that uses microbes to recover minerals and store carbon in mining waste. Adopting this technology to reuse mining waste, called tailings, can transform the mining industry and create a greener and more sustainable future.

Tailings are a by-product of mining. It is a fine-grained waste left after extraction of the target metal ore, which is then stacked and stored. This method is called dry tailing.

Over time, mining practices have evolved and become more efficient. But the climate crisis and growing demand for critical minerals require the development of new technologies for ore removal and processing.

Old tailings contain higher amounts of important minerals that can be extracted with the help of microbes through a process called bio-bleaching. The microbes help break down the ore, releasing any precious metals that have not been fully recovered in an environmentally friendly manner much faster than natural biogeochemical weathering processes.

said Dr. Jeanine McCutcheon, associate professor in the Department of Earth and Environmental Sciences.

In addition to improving resource recovery, microbes capture carbon dioxide from the air and store it within mine tailings as new minerals. This process helps offset some of the emissions released when the mine was active and helps stabilize the tailings.

Mineral microbial carbonates could offset more than 30 percent of annual greenhouse gas emissions at mine sites if applied to an entire mine. In addition, this microbe-driven technology gives value to historical mine tailings that would otherwise be considered industrial waste.

“This technology makes better use of current and former mine sites,” McCutcheon said. “Rethinking how future mine sites are designed in order to incorporate this process may lead to mines that are carbon-neutral from the start rather than thinking of carbon storage as an add-on at the end.

“This technology is a potential game-changer in the fight against climate change, and the mining industry has a unique opportunity to play an important role in the green energy future.”

McCutcheon further believes that microbe-driven processes could help the industry move toward carbon-neutral or carbon-negative mining, but industry participation is critical to moving this technology toward large-scale deployment.

Dr. McCutchen posted this research With co-author and Associate Professor Ian Bauer of Trent University on the peer-reviewed journal Biology PLUS.