There’s a decent chance the phone in your pocket has a little arsenic in it. Gallium arsenide handles radio duties in plenty of electronics, arsenic turns up in some solar tech and batteries, and metallic arsenic now sits on critical mineral lists in several countries, the US included. So here’s a question I didn’t expect to be typing this week: what if one of the best untapped sources of a critical mineral is arguably the nastiest pile of mine waste in Canada?<\/p>\n
That pile sits under Giant Mine, a closed gold mine on the edge of Yellowknife in the Northwest Territories. The mine’s roasters left behind 261,000 short tons (237,000 metric tons) of arsenic trioxide dust, and the Canadian Light Source<\/a> says that’s enough to fill seven 10-story buildings or 9,480 dump trucks. Canada’s answer so far has been to keep the dust frozen underground.<\/p>\n Now a team from the University of British Columbia and the Geological Survey of Denmark and Greenland has taken samples of that dust and converted them into metallic arsenic that came out more than 99 percent pure. The researchers put the converted material under the synchrotron beam at the Canadian Light Source in Saskatoon to study it, and it didn’t look like the arsenic you’d buy. The sample is very pure, GEUS researcher Case van Genuchten says, but “the structure of it is completely different than commercial arsenic.”<\/p>\n Giant was a productive gold mine, with The Northern Miner putting its output at 7.6 million ounces between 1948 and 2004. The catch was the ore itself. Giant’s gold came locked inside arsenopyrite, a mineral made of iron, sulfur and arsenic. The way you cracked arsenopyrite open back then was roasting it. Roasting drove the arsenic off as a gas, and that gas cooled into a fine arsenic trioxide dust.<\/p>\n The mine collected the dust and piped it into chambers and mined-out stopes deep underground, and it kept doing so until owner Royal Oak Mines went bankrupt in 1999. According to Crown-Indigenous Relations and Northern Affairs Canada<\/a>, the dust now fills 14 of the 16 chambers and stopes set aside for it, all of them between 80 and 250 feet below the surface and sealed behind cement bulkheads. The government’s own explainer goes out of its way to note the dust isn’t sitting in barrels. The chambers also stay clear of the lake and of Yellowknife itself.<\/p>\n The stored dust runs about 79 percent arsenic trioxide, with iron, antimony and some leftover gold mixed in. Hold that thought about the gold.<\/p>\n Canada studied hauling the dust out and decided against it, partly because removal would expose workers to the material and partly because the rock around the stopes is irregular enough that thousands of tons would stay behind anyway. The plan the government landed on instead is the frozen block method: freeze the ground around the chambers and keep it frozen, at an estimated cleanup cost of C$4.4 billion. Natalie Plato, the federal official in charge of the remediation, told The Northern Miner the freeze is approved for 100 years.<\/p>\n Freezing your problem in place for a century is, frankly, the kind of plan you make when every other plan looks worse. The government pretty much admits that, since its own material says no true walk-away option exists. Pumps have to keep groundwater below the chambers, and any seepage gets collected and treated. If parking hazardous waste underground while everyone thinks hard about a permanent fix sounds familiar, Germany has been running a version of that movie with radioactive drums in an old salt mine<\/a>.<\/p>\n The Giant Mine Oversight Board, the independent watchdog on the cleanup, keeps pushing research toward a solution that actually ends the problem instead of babysitting it. The new paper is pitching itself as exactly that.<\/p>\n The process, published in Environmental Science & Technology Letters<\/a>, has two steps you could sketch on a napkin. Step one dissolves the dust in water or a weak lye solution, and the team reports that 99 percent or more of the arsenic goes into solution, most of it within an hour when the lye is involved. Step two doses the liquid with thiourea dioxide, an industrial reducing agent, and more than 99 percent of the dissolved arsenic drops back out as a metal in the best runs.<\/p>\n Basically, you rinse the poison out of the dust and then force it to fall back out of the water as a metal.<\/p>\n Remember the gold? It doesn’t dissolve in the reaction, and the Canadian Light Source says that makes the valuable leftovers easier to recover once the arsenic is out. A toxic waste process that hands you gold on the side is a pretty easy thing to like.<\/p>\n So why does the different structure matter?<\/p>\n Chips care about more than which element you feed them; they care how the atoms line up. Commercial arsenic comes as an orderly crystal, while the upcycled material comes out poorly crystalline or outright amorphous. Van Genuchten wants to find out whether that difference helps or hurts when you try to build semiconductors from it, and as far as I can tell, nobody knows yet.<\/p>\n A 99 percent pure product is a big deal for converted mine waste and still a long way from a wafer. The arsenic that goes into chipmaking gets refined to purities with several more nines in them, so there’s real chemistry between this powder and your next gadget. The work so far is lab scale too, done on samples rather than tons. And the paper doesn’t put a price on running the process at volume; I couldn’t find a cost estimate anywhere else either.<\/p>\n The team isn’t lowering its sights over any of that. Tamara Etmannski, the UBC engineer on the project, wants large amounts of metallic arsenic for electronics manufacturing, and she wants the stockpiles themselves gone. Canada has developed a taste for this kind of trick lately; an Ontario project is busy turning captured carbon into stone<\/a>. “It would be mining its own waste,” Etmannski told CBC.<\/p>\n Etmannski and van Genuchten published the results in Environmental Science & Technology Letters on August 11, 2026, and Etmannski says the next step, once the team shows it can make a semiconductor out of the converted arsenic, is finding out whether the process can scale up at Giant Mine itself.<\/p>\n","protected":false},"excerpt":{"rendered":" There’s a decent chance the phone in your pocket has a little arsenic in it. Gallium arsenide handles radio duties … <\/p>\nSo where did 261,000 tons of arsenic dust come from?<\/h2>\n
The current plan is a freezer that runs for a century<\/h2>\n
The chemistry is pretty simple, at least on paper<\/h2>\n
Don’t order a mine-waste phone just yet<\/h2>\n