Frequently Asked Questions: Arsenic Trioxide Management

What is arsenic trioxide? 

Arsenic is a naturally occurring element found throughout the environment. Some forms of arsenic can be harmful to people, animals, or plants. The arsenic waste created during the mining process is a specific form called arsenic trioxide. An inorganic compound, arsenic trioxide is a by-product of mining operations created during Giant Mine’s operations: when arsenopyrite ore was roasted to release the gold, arsenic was also released as a gas, called arsenic dioxide. As the gas cooled, it changed to a solid state and became arsenic trioxide dust. 

Crown-Indigenous Relations and Northern Affairs Canada has compiled useful information about arsenic trioxide.

How much arsenic trioxide dust is stored underground at the Giant Mine site? 

Currently, 237,000 tons of arsenic trioxide dust are stored in 14 underground chambers at the Giant Mine site. 

How is the arsenic trioxide dust at the Giant Mine site currently being managed?

The arsenic trioxide dust is currently frozen in place until a more permanent solution is found, using the ‘Frozen Block Method’. This method was determined to be the safest way to currently manage the waste and prevent it from dissolving into the groundwater and spreading into the surrounding area.  As technology continues to evolve, GMOB will work with its partners and continue to support research into a permanent management solution. 

Learn more about the Frozen Block Method.

Is arsenic trioxide dangerous? 

Arsenic trioxide can present a health hazard and can be harmful to people, animals and the environment. The stored arsenic trioxide dust is a significant source of concern for people and communities in the surrounding area of the mine site. This potential for harm is why arsenic trioxide waste must be carefully managed. 

What are the challenges managing arsenic trioxide dust? 

The challenge of dealing with arsenic trioxide dust is complex due to the huge quantity of the dust, its physical characteristics (the dust is like a fine flour), and the varied storage conditions of the dust. 

Learn more about finding a permanent solution for stored arsenic trioxide dust.

Does GMOB have the technical expertise to manage this research? 

GMOB has partnered with mine site remediation research experts, Toward Environmentally Responsible Resource Extraction (TERRE-NET), to help carry out this research project. TERRE-NET brings together leading experts from Canadian universities working in the fields of geochemistry, hydrogeology, mineralogy, biogeochemistry, mine effluent treatment, geotechnical engineering, nanotechnology, environmental microbiology, resource economics, environmental sociology and Indigenous Knowledge. 

Learn more about TERRE-NET

What does the research focus on? 

There are four major research initiatives: 

What is the current status of the research project? 

Due to COVID-19 pandemic restrictions, all research initiatives slowed considerably due to laboratory closures. Research laboratories are slowly re-opening and GMOB and TERRE-NET hope to actively continue research moving forward into 2022 and beyond. 

Where can I learn more about the research completed so far? 

TERRE-NET compiles progress reports on the arsenic management research program. View them here:  

Is GMOB accepting proposals to conduct additional research? 

GMOB accepts research proposals specific to finding a permanent solution for the management of stored arsenic trioxide.  Proposal submission deadline is September 1st of each year. 

Additional research proposal details: 

  • Proposals must be submitted in the Proposal Template. All sections must be complete to be considered. If a section is not applicable, please indicate the reason; do not leave the section blank or it will be deemed incomplete. 
  • An independent research committee will evaluate all proposals. 
  • Successful applicants will be notified within 60 days of submission. 
  • Enquiries related to proposal submissions:

Research Proposal Template