Mining e-waste for valuable metals

The University of New South Wales is unveiling a pilot microfactory that safely transforms toxic e-waste into high-value metal alloys, offering a low-cost solution to a fast-growing problem. The process, invented by UNSW ARC Laureate Professor Veena Sahajwalla, will enable the safe, cost-effective ‘mining’ of e-waste stockpiles locally, anywhere in the world.

As noted by Professor Sahajwalla, e-waste contains a range of valuable metals. “A tonne of mobile phones (about 6000 handsets), for example, contains about 130 kg of copper, 3.5 kg of silver, 340 g of gold and 140 g of palladium, worth tens of thousands of dollars,” she said.

Unfortunately, e-waste is particularly challenging to recycle due to the presence of toxins and the complex mix of materials. Safe e-waste processing has thus been restricted to high-cost, industrial-scale facilities with very large furnaces, leaving many communities around the world without a viable solution. Any e-waste that doesn’t end up in landfill is exported from industrial economies to developing nations, where hand processing to recover metals exposes poor communities to dangerous contaminants.

Now, Professor Sahajwalla has invented a process which uses precisely controlled high-temperature reactions to produce copper- and tin-based alloys from waste printed circuit boards (PCBs) while simultaneously destroying toxins. A programmed drone is able to identify PCBs from within crushed e-waste and a simple robot is used to extract them, overcoming the risks of contamination, before the PCBs are fed into the furnace.

Furthermore, Professor Sahajwalla’s microfactories are suitable for mobile use: they can be set up in containers and transported to waste sites, avoiding the huge costs and emissions of trucking or shipping e-waste over long distances. Likewise, they promise a safe new way for poor communities in developing nations to generate an income from the production of metal alloys.

“The world urgently needs a safe, low-cost recycling solution for e-waste,” said Professor Sahajwalla. “Our approach is to enable every local community to transform their e-waste into valuable metal alloys, instead of leaving old devices in drawers or sheds, or sending them to landfill.”

The solution is being showcased at UNSW’s Centre for Sustainable Materials Research and Technology (SMaRT), which is directed by Professor Sahajwalla.