Making e-Waste SCARCE

NTU Singapore-CEA Alliance for Research in Circular Economy (SCARCE)

“Electronic waste materials may not be often talked about or easily understood as the technological solutions are highly complex, but these innovations go a long way towards ensuring that the tech we use every day is cleaner, and more sustainable.”

- Professor Jean-Christophe Gabriel, Co-Director SCARCE Joint CEA-NTU Laboratory

As technological innovations rapidly increase around the world, so does the resulting electronic waste. The growth trajectory for the e-waste management market has been estimated to rise from $57.8 billion in 2022 to reach $244.6 billion by 2032¹.

Amongst these electronic waste materials are waste printed circuit boards (WPCBs) which are considered the most valuable component as many elements, such as precious and critical metals as well as rare earth elements are contained in electronic components such as memory and integrated circuits chips, capacitors, transistors, etc. The presence of these metals in WPCBs is at higher concentration than in typical ores extracted from mines, but in a much more complex and variable mixture. Therein lies the challenge. Despite their value, conventional recycling methods like pyrometallurgy result in a significant loss of these valuable metals, as they end up in the ashes. On average, WPCBs account for approximately 8% of the weight of electronic waste materials collected from small appliances.

Beyond the precious metals currently recovered, such as silver, platinum, gold, and other critical materials (e.g. cobalt, antimony, neodymium, tantalum) should also be recovered as resources and the heavy metals (e.g. copper, iron, tin, lead, chromium) must be adequately dealt with to prevent public health and environmental concerns.

With Singapore being one of the most digitalised countries in the region, it was imperative for Singapore to innovate and find a solution to recycle e-waste. Traditional metal recovery methods for PCB are challenging due to the complex mixture of the many metals present within the PCB components. Hence, to maximise profit margin, industries could only selectively recover valuable metals such as gold and copper.

[Left] The sorting tool depicted here enables the automatic sorting of electronic components from waste-printed circuit boards. The feeder brings electronic components through the tool on a conveyor belt, where cameras and a multi-energy X-ray generator sort the components by their metallic composition.

[Right] A prototype of the sorting tool used to present the team's technology. The photo depicts the optical recognition of an electronic component enabled by an artificial intelligence programme.

In the SCARCE project (Phase 1), the team developed a prototype tool to automatically sort various individual electronic components (ECs) from WPCBs into similar EC types or group EC with similar metallic compositions. Such sorting would enable the recovery of many more metals as compared to those recycled from conventional recycling methods. This change in processes to concentrate the recovered metal will also greatly simplify and enhance the recovery efficiency. This novel approach helps in reducing the downstream treatment cost and provides a cost-effective solution to recover previously discarded critical metals such as rare earth metals (neodymium, dysprosium, etc.), refractory metals (niobium, molybdenum or tantalum) or other valuable/critical/toxic elements (e.g. manganese, led, antimony).

In Phase 2 of this research, the team will focus on testing and scaling up the innovation for industrial and real-life applications. It will also evaluate the economic viability and establish partnerships with potential industry collaborators for commercialisation.​

^{[1] Source: https://www.alliedmarketresearch.com/e-waste-management-market}