Urban Mining?: Researchers Find Way to Vaporise E-waste Down to Its Precious Metals

Researchers have extracted precious metals from e-waste in a way that's better for the environment fights one of the fastest-growing hazards to our climate and health.

Author Christian Nathler, 11.22.21

Translation Sarah-Indra Jungblut:

Every time you throw away an iPhone, the Earth sheds a tear. This is not an exaggeration:  e-waste is now the world’s fastest-growing form of domestic trash. We dump up to 50 million tons of it annually, and with less than a fifth of it given a second life, our demand for digital products will only continue to burden the planet.  

But there is hope. Recently, researchers at Rice University found a novel way to extract value from all the technojunk taking up space in our drawers and landfills. It’s called flash joule heating or, in layperson’s terms, making something very hot very quickly. It works by shocking a circuit board, say, with a 3000°C electric current, thereby vaporising the toxic components and isolating the precious metals. The harvest is not insignificant: the average cathode ray tube (CRT) television, a curbside staple, yields almost a pound of copper, more than half a pound of aluminum, and even 0.02 ounces of gold after evaporative separation.

Even more impressive is the environmental benefit. Recovering precious metals from e-waste, or “urban mining,” is up to 500 times more energy-efficient than traditional smelting (tossing ore into a furnace), and the leftover waste is less toxic. Furthermore, the study points out that “concentrations of some precious metals in e-waste are higher than those in ores, and mining them could be up to 13 times cheaper. “This will curtail the need to go all over the world to mine from ores in remote and dangerous places, stripping the Earth’s surface and using gobs of water resources,” said James Tour, lead author of the study. “The treasure is in our dumpsters.” 

Tour and his colleagues’ work represents the first time flash jouling has been used to mine electronics. The process is also used to turn cheap carbon sources into high-quality graphene or diamond. In both cases, the conversion from scrap to precious material happens in less than a second. Compare that to the time and energy needed to fire up a smelter and keep it cooking, and it’s no wonder the Rice researchers consider flash joule heating “scalable” with the potential for “near-future” applications beyond the lab. “We could increase the FJH voltage and/or the capacitance of the capacitor bank when scaling up the sample mass,” the researchers say. In other words: the more junk, the higher the heat.

Stopping E-Waste at its Source?

Of course, hail mary solutions can distract from the need for systemic change. The real challenge in thinking about e-waste isn’t figuring out what to do with it – it’s deciding how to avoid it in the first place. Culpability is not evenly distributed. The world’s top e-waste producers per capita are all wealthy countries (or, apparently, countries whose flags contain red, white and/or blue). Perhaps we should approach our consumer relationships as we do our romantic ones, in which we repair what’s broken instead of throwing it away and we know better than to fall for the latest model. On the sell side, it starts with manufacturers abandoning business strategies like planned obsolescence, where artificial lifespans are part of the product design. Modular smartphones, whose various components can be independently upgraded or replaced, are just one example of how these efforts can merge.

Realistically, we won’t be able to torch our iPods for gold anytime soon. Nevertheless, being able to spawn new electronics from the graveyard of old gadgets is a win for the circular economy.

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