Researchers produce 99 percent pure metallic arsenic from Yellowknife mine waste
- Researchers extracting samples from 261,000 short tons of arsenic trioxide dust buried beneath a closed gold mine in Yellowknife have produced metallic arsenic exceeding 99 percent purity.
- Giant Mine operated as a productive gold mine from 1948 until 2004, yielding approximately 7.6 million ounces of gold, according to records from The Northern Miner.
- Scientists analyzing the stored dust successfully converted the material into metallic arsenic testing above 99 percent purity.
Researchers extracting samples from 261,000 short tons of arsenic trioxide dust buried beneath a closed gold mine in Yellowknife have produced metallic arsenic exceeding 99 percent purity. The material, recovered from the Giant Mine site by a joint team from the University of British Columbia and the Geological Survey of Denmark and Greenland (GEUS), presents an unexpected potential source of a critical mineral as global supply chains face mounting pressure.
Origins of the Giant Mine Arsenic Stockpile
Giant Mine operated as a productive gold mine from 1948 until 2004, yielding approximately 7.6 million ounces of gold, according to records from The Northern Miner. The gold was locked within arsenopyrite, an ore composed of iron, sulfur, and arsenic. To release the gold, operators roasted the ore, driving off arsenic as a gas that subsequently cooled into fine arsenic trioxide dust. When owner Royal Oak Mines went bankrupt in 1999, the operation left behind 237,000 metric tons of the toxic byproduct. Crown-Indigenous Relations and Northern Affairs Canada notes that this dust now fills 14 chambers and mined-out stopes situated 80 to 250 feet beneath the surface. Cement bulkheads seal these chambers, which contain material running roughly 79 percent arsenic trioxide alongside iron, antimony, and leftover gold.
Laboratory Analysis and Purity Results
Scientists analyzing the stored dust successfully converted the material into metallic arsenic testing above 99 percent purity. Researchers examined the converted substance using the synchrotron beam at the Canadian Light Source in Saskatoon. GEUS researcher Case van Genuchten noted that while the sample is exceptionally pure, its physical structure differs entirely from commercial arsenic available on the open market.
Federal Remediation and the C$4.4 Billion Freezer Plan
Canada previously evaluated removing the massive waste volume but rejected excavation due to worker exposure risks and the irregular geometry of the surrounding rock, which would leave thousands of tons behind. Instead, the federal government approved a frozen block remediation method carrying an estimated cleanup price tag of C$4.4 billion. Natalie Plato, the federal official managing the remediation, confirmed to The Northern Miner that the containment freeze is authorized to run for a century. Pumps maintain groundwater levels below the storage chambers, collecting and treating any seepage as part of the ongoing containment strategy.
