Electronic waste is proving to be a far richer source of valuable metals than any ore pulled from the ground, according to mining engineers at the University of British Columbia.
PhD student Amit Kumar and professor Maria Holuszko have succeeded in "mining" copper and silver from LED lights, and they are certain that rare earth metals such as europium, cerium and lutetium can also be recovered.
Light Emitting Diodes are gaining popularity as a highly efficient alternative to incandescent and fluorescent lights and represent an increasing proportion of e-waste and a potential source of metal pollution, said Holuszko.
"We believe that within three years there will be enough LEDs in the waste stream to make this viable," said Kumar. "And if we don't do it, they will all end up in the landfill."
What makes the LED recycling process tricky is that lights are made of fused composite materials that blend plastics and metals with a variety of other compounds that cannot simply be pulled apart.
But if LEDs are ground up fine enough, the material isn't much different from a high quality ore, though one with a variety of metals and industrial materials to be recovered.
"We are using techniques like the ones employed by the mining industry, mainly physical processes that exploit the weight, density and conductivity of the metals to separate them from other materials," said Kumar. "So far we haven't needed to use any chemicals, so it's a very clean process."
The researchers employ gravity, electrostatic separation, and other non-chemical methods to separate metals from each other and from binding materials.
Processed samples contain up to 65 per cent recoverable copper - far higher than processed ore - along with 4.5 per cent zinc and 1,640 parts per million of silver.
"Eventually, we also hope to use this workflow to find a way to recover gold in significant amounts," said Holuszko.
Recovering rare earth metals will likely be accomplished with a chemical process, but only the small amount of material that remains after the common metals are removed would need to be treated, said Kumar.
A successful test run of the process with Richmond's Contact Environmental recovered copper, zinc, lead and silver, according to Holuszko. The next step is to find an industrial partner interested in investing in a real-world pilot program.
"We have a grant from (non-profit innovation funding agency) Mitacs, but it's not enough without a private partner," she said.
