Transforming Toxic Mine Tailings — into Goldhttps://www.watertapontario.com/news/transforming-toxic-mine-tailings/44
Wednesday January 8th, 2014
Ontario-based environmental remediation services company BacTech Environmental Corporation recently tried a “crowdfunding” approach to fund sending specialized environmental remediation technology to help an impoverished community in southern Bolivia suffering from groundwater and soil contamination caused by acid rock drainage from decades-old mining excavations. Crowdfunding failed to raise the necessary funds needed for the Bolivia project this year, but the resulting publicity spotlighted BacTech’s efforts to deploy their advanced "bioleaching" technologies to protect groundwater and soil contamination from old mine tailings sites in Manitoba — and here in Ontario.
Acid rock drainage:A worldwide problem
“I’m a businessman, not an environmental activist,” says Ross Orr, President and CEO of BacTech Environmental Corporation, at his desk inside the company’s downtown Toronto headquarters. “But what we’re doing most certainly protects the environment, and helps people in many ways — at no cost to taxpayers.”
BacTech Environmental Corporation (www.bactechgreen.com), a publicly traded company founded in 2010, specializes in environmental remediation services that remove and neutralize acid-generating sulfides, arsenic, and base metals from “mine tailings,” piles of excavated dirt and waste materials accumulated from years of mining operations.
A worldwide problem, abandoned mine tailings containing sulfides eventually create an environmental hazard called acid rock drainage (ARD), seeping into soil over time and eventually contaminating and poisoning groundwater supplies. BacTech’s proprietary "bioleaching" technologies using harmless bacteria separates and safely oxidizes the sulphide materials from the mine tailings, accomplishing in mere days what would normally require more than 20 years to occur naturally.
“There’s more than 10,000 mine tailing sites just in North America that need to be cleaned up, ranging from the size of my office to the size of the Berkeley Pit in Montana,” says Orr. “Most of these mine tailing sites are more than 50 or 60 years old, and the mining companies responsible have long since disappeared. Because today’s mining industry does such a good job of getting the sulfides out of the rock in current projects, the really nasty sites are usually next to abandoned mines and are now owned by governments, like with our Snow Lake project in Manitoba and our potential projects in Bolivia and Peru.”
Pure gold payoff
BacTech’s environmental remediation technologies neutralize sulfides causing acid rock drainage and stabilize toxic elements such as arsenic and cadmium, but the process also isolates and separates base metals present in the mine tailings, including copper, nickel, cobalt, zinc — and gold and silver.
Recovering precious metals from mine tailings funds the construction and operation of the bioleaching plant, and returns a tidy profit as long as the price of gold continues current high value. Governments and municipalities are eager to talk to BacTech about processing tailings at old mining operations, especially since the company charges no fee for their environmental remediation efforts.
“It’s like offering to clean your old sofa for free, but we get to keep any lost coins we find under the cushions,” says Orr. “With the price of gold up from $300 an ounce to as high as $1300 an ounce, these old mine tailings can potentially be an asset instead of a toxic liability, assets that governments and municipalities can exchange for environmental cleanup that eliminates threats to their precious water supply.”
Patented bioleaching process
BacTech’s patented bioleaching process begins with removing mine tailings to a nearby flotation plant that produces a concentrate containing sulfide minerals and metals. About 95% of the processed tailings are returned to original tailings pile as harmless and inert rock, while the remaining 5% concentrate goes into a series of bioleaching tanks containing bacteria that consumes the sulfides.
Within days, bacteria thriving on the metal-rich concentrate containing arsenopyrite and pyrite split the toxic molecules and consume the sulfur, making the iron and arsenic water-soluble. The processed “liquor” moves to a thickener, where a solid/liquid separation process segregates and removes any gold and silver with the remaining solids, while the liquid contains soluble arsenic and other base metals.
The neutralization process adds limestone to the liquor to neutralize iron and arsenic, and selectively recovers any copper, nickel, cobalt, or zinc present. After adding water, environmentally non-toxic products are produced, including ferric arsenate, gypsum, and ferric hydroxide, all delivered back to the original tailings pile. Recovered gold and silver are pumped from the thickener to a conventional metals recovery plant, and the bioleaching process continues until all of the tailings have been reclaimed and neutralized, and the project area has been returned to nature.
Next stop: Ontario
BacTech’s $20 million Snow Lake, Manitoba plant slated for construction in the spring of 2014, subject to financing, is the company’s first industrial application of its bioleaching remediation technology with mine tailings, though the technology has been licensed and used for years previously in mineral processing. The Snow Lake plant will process and neutralize a 60-year old pile of arsenopyrite (arsenic sulfide) at no cost to the Manitoba provincial government, and the company is talking with several communities and First Nations settlements across western Ontario, where old mine tailings threaten to contaminate the local groundwater supply.
“I get a lot of calls from First Nations communities located northwest of Thunder Bay, including Kenora, Sioux Lookout, Geraldton-Beardsmore, and Red Lake, which is famous for gold mining in western Ontario,” says Orr. “There are about 25 sites next to old mines located near remote communities who worry about the water contamination from acid rock drainage.”
To service the needs of these Ontario communities, BacTech is considering building a mobile processing station mounted on a large truck flatbed that can easily be moved from site to site. On-site reprocessing of tailings will create a concentrate that will be shipped to Manitoba for final processing and base-metal separation at the Snow Lake plant. Lessons learned from these Manitoba and Ontario projects will be applied to the potential bioleaching remediation projects in Bolivia and Peru, where millions of tons of mine tailings dating back more than 100 years have been severely contaminating soil and rivers used by local communities.
“The mining industry of 50 to 100 years ago was probably unaware of the long-term contamination problems they were creating, just like the Manitoba farmers who put phosphates on their fields that eventually leached into Lake Winnipeg and created a huge algae mess today,” says Orr. “Our technology enables us to remedy these environmental mistakes of the past, and pay for it using precious metals produced from the cleanup process — no government funding needed.”
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