Nano-particle metallic alloys from printed circuit boards

Ali Shokri, Farshid Pahlevani, Katie Levick, Ivan Cole, Veena Sahajwalla

This study investigated and verified the selective thermal transformation of metals within e-waste to achieve, for the first time, the direct production of value-added Copper-Tin (Cu-Sn) nanoparticles and the simultaneous separation out of toxic Lead (Pb). In this project we were able to develop a new concept for the processing of complex waste – called thermal micronizing – which is expected to be transferrable well beyond this study. Thermal micronizing leverages the gases generated from the waste plastics with within complex waste streams such as e-waste, to enable the formation of sub-micron particles for industrial applications, in this case value-added Copper-Tin (Cu-Sn) nanoparticles. By investigating the thermal transformation mechanisms, we showed the diffusion of Sn into the Cu due the high solubility of Sn in Cu, while the Pb was separated out due to the low solubility of Pb in Cu. The plastics in the waste generated a reducing environment, so acted as ‘thermal micronizing’ media which micronized the liquid Cu-Sn alloy as well as protecting the nanoparticles from oxidation. The residual carbon limited the direct contact between the metallic nanoparticles and so minimized agglomeration. This study produced a novel pathway for safely transforming problematic e-waste into value added resources, via a ‘thermal micronizing’ process.

·      New concept developed – thermal micronizing – with applications well beyond this study
·      New safe, cost-effective pathway for recovering valuable alloys from e-waste
·      Complete recycling process that address the limitations of current e-waste recycling methods that generate significant problematic residue

Potential for deployment in small scale local micro-factories that bring the solution to the problem in both developed and developing countries.

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