LATEST NEWS Water & Wastewater
May 8, 2013
Manitoba mine clean-up spins gold
An environmental company is cleaning up a toxic Manitoba mine site at no cost to taxpayers, but it gets to keep any gold it can extract from a stockpile of arsenopyrite concentrate.
“As the price of gold and copper began to rise, we realized the possibility for extracting value from mine tailings,” said Ross Orr, president and CEO of Toronto-based BacTech Environmental Corporation.
The company is employing bioleaching technology, which uses microbes to extract valuable metals from undesirable materials.
“Bacteria digest the sulphides to break up the matrix of the tailings materials,” said Orr.
“The arsenic and iron go into the solution and the precious metals go into a precipitate for which we can use conventional extraction methods.”
While the technology isn’t new, the application is.
The plant would be the world’s first bioleaching facility for the remediation of toxic material.
The company initially met with some resistance, however, when it presented its ideas under its other banner, mining firm REBgold Corporation.
“There’s an opinion out there among some people that dealing with a mining company is like dealing with the devil,” said Orr.
The company split into two entities in 2010, with REBgold continuing mining efforts, while BacTech pursued environmental remediation.
Orr said he began his search for toxic tailings that might contain gold by simply Googling “mine tailings” and “arsenic problems.”
He quickly found a site located in the community of Snow Lake in Northern Manitoba, about 700 kilometres north of Winnipeg.
“The site was operated as the Nor Acme Mine for 10 years and went broke in 1959,” he said.
“It holds 300,000 tonnes of concentrate and contains up to 20 per cent arsenic. The concentrate was stored on site, but eventually dumped into the lap of the taxpayer.”
The tailings pile is uncovered and measures between six and 10 metres deep over an area of almost 20,000 square metres.
Environmental assessment indicates that acid and arsenic are currently leeching from the stockpile into the surrounding watershed.
After receiving permission to sample the stockpile for gold content, Orr determined that it contained approximately 9.7 grams of gold, or about one-third of an ounce, per tonne.
In full production, the plant could net 10,400 oz. of gold per year.
Orr next approached Dave Chomiak, Manitoba Minister of Innovation, Energy and Mines, with a remediation proposal that would result in the stabilization and neutralization of the arsenic stockpile.
“He asked me how much it was going to cost him, and I told him that I wasn’t interested in the province’s money,” said Orr.
“He told me that it would be an easy deal and two days later I had a signed letter of agreement with the province.”
BacTech is anticipating that construction of the $22 million plant will start this year with processing operations commencing by next spring.
The plant will employ 30 people, who will process 100 tonnes of tailings per day on a 24-hour schedule for an expected seven years.
With the addition of limestone, the tailing remnants will be transformed into ferric arsenate, a stable substance that will be piped into a clay-lined pit and dewatered.
Recovered water will be re-used in the bio-leaching process.
The final step will be to cap the material with three metres of additional clay.
BacTech has recently awarded a drilling contract to Rodren Drilling Ltd. of Winnipeg to sample tailings from 10 other defunct mines at nearby Anderson Lake, six kilometres south of Snow Lake.
If the samples prove economically viable, the Snow Lake plant could double its service life.
BacTech has also expressed interest in taking on the Giant Mine tailings project in Yellowknife.
Aboriginal Affairs and Northern Development Canada recently estimated taxpayers may be on the hook for as much as $900 million to remediate the site.
“We’re wondering why there isn’t an effort being made to recover some of the 900,000 ounces of gold in the tails,” said Orr.
“We’ve also offered to take on their problem at no cost to taxpayers, as well as stabilizing the arsenic and eliminating any future acid rock drainage, but so far our offer has fallen on deaf ears.”
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