Between 1948 and 2004, over seven million ounces of gold were extracted from the Giant Mine. The roasting process used to extract the gold also produced 237 000 tonnes of arsenic trioxide (As2O3), a highly toxic and soluble by-product. Now stored underground, this waste is one of Canada’s largest environmental liabilities, with an estimated $1 billion in remediation costs. Current remediation plans focus on a ground-freezing system to prevent groundwater ingress to the stored waste and subsequent dissolution and arsenic mobilization, but this will require operation and maintenance forever. As a result, a federal environmental impact assessment panel assigned the responsibility to the Giant Mine Oversight Board (GMOB) for finding a safe and permanent solution to the management of the As2O3 waste. The GMOB then set a goal to partner with the country’s top researchers.
A partnership, with research funding of $150,000 over three years, was recently formed between Prof. Al, the GMOB and NSERC’s TERRE-NET research network, to transform arsenic waste into a low-solubility arsenic sulfide (As2S3). Contrary to the environmental concerns raised by the oxide form of the waste (As2O3), the sulfide form has much lower solubility and it is stable in an anaerobic environment so it could be permanently disposed of deep within the mine. Evelyn Tennant, a master’s student, is currently exploring methods to dissolve the arsenic trioxide waste – a necessary first step - and characterize the residue. Erika Revesz, a research associate in Professor Al’s group, is testing methods to generate aqueous sulfide using elemental sulfur and different forms of organic carbon. Professor Al explains that if arsenic sulfide (As2S3) can be generated from the waste in a manner suitable for large-scale implementation, Giant Mine could be flooded to restore natural groundwater conditions without the risk of arsenic contamination of nearby Great Slave Lake.
This partnership opportunity is incredibly beneficial to Canadians, the GMOB and Prof. Al’s research group at the University of Ottawa. First, finding a permanent solution is crucial to prevent passing the contamination risk and cost to Canada’s future generations. Prof. Al’s research partnership aims to create a stable form of arsenic that can be safely isolated deep in the mine without long-term maintenance requirements. He refers to this as a “walk-away” solution. Second, since GMOB is not a research organization, its research mandate can only be achieved through partnerships such as the one that currently exists with the University of Ottawa. Finally, this partnership represents an extremely engaging research opportunity for Professor Al and his students. He shares, “At Giant Mine, there have been 20 years of research and we are pleased to be engaged in the effort to find a walk-away solution. If all goes well, we will see some success and this will bring long-term social and environmental benefits to the Yellowknife region and favourable attention to the University of Ottawa.”
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