Snow Lake Concentrate Stockpile - Manitoba
Background
In early 2010 BacTech became aware of a reclamation opportunity. In the 1950s, a gold mine owned by
The Britannia Mining and Smelting Company was opened and operated at Snow Lake, Manitoba.
Approximately 10% of the ore was classified as arsenopyrite (arsenic bearing) and refractory in nature,
which required additional treatment to liberate the gold for recovery. Given the high levels of arsenic that
reported to the concentrate, conventional roasting or smelting were ruled out as process options and the
concentrate was treated by direct cyanidation to recover as much gold as possible. The residue was
stockpiled at the mine site to await future technologies capable of extracting the remaining gold values.
Approximately 350,000 tonnes of concentrate residue was stockpiled onsite at the New Britannia mine,
with a reported grade of 10-11grams per tonne (g/t). Over the past 50 years there has been a gradual
oxidation of the contained sulphide minerals, which produces sulphuric acid and arsenic to be discharged
from the stockpile.
After a series of different owners over the years the material eventually became the responsibility of the
Manitoba Government, which classified the stockpile as an abandoned site. Given the high levels of
arsenic in the stockpile prospective purchasers of the mine were reluctant to include the stockpile as part
of the assets of the New Britannia Mine and owners negotiated the acquisition of the mine without
assuming responsibility for the stockpile.
BacTech Participation
BacTech approached the Manitoba Ministry of Science, Technology, Energy and Mines in April 2010 and
outlined a plan whereby BacTech, at its own expense, would use samples obtained from the concentrate
stockpile to determine whether the material was amenable to bioleaching for liberating and extracting the
gold while stabilizing the arsenic as a ferric-arsenate. The Manitoba government granted approval for
BacTech to conduct the sampling program, subject to oversight by an independent engineering consulting
firm which the government engaged to ensure that there would be no adverse environmental impacts from
drilling through the arsenopyrite.
In mid-September, BacTech presented the positive results of its preliminary study to the Government of
Manitoba and has followed up with a proposal to conduct a larger metallurgical/bioleach study. The
proposed study, which would again be completed at BacTech’s expense, will involve the drilling of a
number of holes on the concentrate stockpile to obtain approximately 1000 kg of material. The study will
be used to confirm the amount of gold present as well as the metallurgical variability of the stockpile. In
addition, the study will evaluate pre-treatment scenarios and costs, continue bioleach work on a larger
scale for gold extraction and also study the detox/arsenic stability for the oxidized end product. The study
is expected to last 6-8 months. If the Manitoba government authorizes the further study, it will be
conducted by Greenco following the Arrangement.
https://www.bactech.com/i/pdf/BacTech_Notice_MIC_Appendices_Oct14_2010.pdf