A Deeper Understanding

The benefits of bioleaching extended beyond just the remediation of tailings and other mining stockpiles. Bioleaching addresses several tailings-related environmental issues at once, while generating revenue that can effectively fund the remediation process.

Bioleaching uses naturally-occurring bacteria in reactors (tanks) to oxidize sulphides. The key is providing the bacteria with optimal operating and living conditions in the reactors. They are capable of oxidizing sulphides in as little as 5–6 days, as opposed to many years in their natural habitat. This is a common residence time in a commercial bioleach plant and the control of this and other parameters, such as the particle size of feed, are relatively simple and readily managed by operators with the correct training.

Following BacTech’s first application for bioleaching, the Company added a second application for the use of bioleaching. Through a professor at the University of British Columbia, we learned of the dangerous use of mercury in artisanal mining in various countries. This uncontrolled use has led to widespread environmental degradation in Peru, Ecuador and Colombia, to name a few countries. Through the use of flotation, arsenopyrite concentrates are produced that, when processed with bioleaching, produce gold and a benign form of arsenic, called ferric arsenate. In this scenario, bioleaching is able to recover more gold and replace the use of mercury to provide a greener solution.