VANCOUVER (miningweekly.com) – Researchers at the University of British Columbia (UBC) have developed a flowsheet to extract copper, lead, zinc, silver and small amounts of rare earth metals, including lutetium, cerium and europium, as well as the ‘technology metals’ gallium and indium from discarded light-emitting diode (LED) bulbs.
Mineral processing engineer Dr Maria Holuszko and her PhD student, Amit Kumar, have found a way to make LEDs even more environment-friendly, developing a technology that could help in keeping industrial and precious metals out of landfills.
“This mining of metals from waste streams is what ‘urban mining’ is about. While urban mining, even at its most efficient, can probably only meet about a quarter of the current demand for metals, it can complement traditional mining and do the environment good at the same time,” states Holuszko in an email interview.
She explains that the recycling flowsheet processes use crushing, grinding and other simple physical processes to recover valuable metals in an economic and environmentally safe manner. The methods are based on material properties, such as density, electrical conductivity, shape and size, resulting in simple, clean and economical processing.
“Our methods resulted in capturing higher amounts of recoverable, valuable metals in the final sample. The copper content alone was at 65%, compared with the 30% or 40% copper content usually obtained from ore in traditional mine processing. The lead content was 6%, zinc was 4.5% and silver was 1 640 ppm – pretty good concentrations. Eventually, we also hope to use this workflow to find a way to recover gold in significant amounts,” Holuszko says.
The researchers plan to scale the process, and have to date conducted a test run of the process in collaboration with Contact Environmental, British Columbia’s largest lamp recycler, located in Richmond.
“We’ve proven that it works, with significant amounts of copper, lead, zinc and silver being recovered and kept out of landfills. We plan to improve the recovery of metals even further and eventually implement this processing on a larger scale in 2017, with funding support from research not-for-profit Mitacs,” she said.
Further, electronic waste from old computers, cellphones, LED lights and other electronic devices is a growing problem for North American communities and also for developing countries that process waste.
“If we can extract the maximum amount of material from e-waste, we would make it easier and safer to recycle. We will be able to limit other communities’ exposure to potentially toxic materials, while also recovering valuable minerals. My dream is to find a way to close the cycle so that in the future, there is zero waste,” Holuszko says.