Electronic Waste Disassembly with Industrial Waste Heat

Abstract

Waste printed circuit boards (WPCBs) are resource-rich but hazardous, demanding innovative strategies for post-consumer collection, recycling, and mining for economically precious constituents. A novel technology for disassembling electronic components from WPCBs is proposed, using hot air to melt solders and to separate the components and base boards. An automatic heated-air disassembling equipment was designed to operate at a heating source temperature at a maximum of 260 °C and an inlet pressure of 0.5 MPa. A total of 13 individual WPCBs were subjected to disassembling tests at different preheat temperatures in increments of 20 °C between 80 and 160 °C, heating source temperatures ranging from 220 to 300 °C in increments of 20 °C, and incubation periods of 1, 2, 4, 6, or 8 min. For each experimental treatment, the disassembly efficiency was calculated as the ratio of electronic components released from the board to the total number of its original components. The optimal preheat temperature, heating source temperature, and incubation period to disassemble intact components were 120 °C, 260 °C, and 2 min, respectively. The disassembly rate of small surface mount components (side length ≤ 3 mm) was 40−50% lower than that of other surface mount components and pin through hole components. On the basis of these results, a reproducible and sustainable industrial ecological protocol using steam produced by industrial exhaust heat coupled to electronic-waste recycling is proposed, providing an efficient, promising, and green method for both electronic component recovery and industrial exhaust heat reutilization.

Life cycle assessment and environmental profile evaluations of high volumetric efficiency capacitors

“…It is not highlighted as a hotspot in this study because of the low volumes in which it is used. Despite this, as the material is not currently recycled from these electronic components the earth's reserves are continually being depleted [60,61].…”

“…). Chen et al[60] have documented that unregulated recyclers in developing regions such as Africa and Asia use handmade tools to disassemble electrical components by heating a WPCB on a coal-heated plate in order to melt the solder. This causes severe pollution to the environment and exposure to toxic chemicals for those involved in the work.…”

Evolution of electronic waste toxicity: Trends in innovation and regulation

“…Printed circuit boards are essential components of all the electrical and electronic equipment, where most of the valuable and potentially hazardous materials are concentrated. Recovery, dismantling, and recycling are considered among the most effective approaches to waste printed circuit boards (WPCBs) management, but large-scale implementation has been challenging because of projected low cost-to-benefit ratio of processing mixed e-waste components (Chen et al, 2013). Improved understanding of the chemical compositions of WPCBs has aided recyclers (Dervišević et al, 2013;Lee et al, 2012;Richter et al, 1997;Yin et al, 2011).…”

Thermal degradation and pollutant emission from waste printed circuit boards mounted with electronic components

“…(Park et al (2015)) invented a disassembly apparatus for WPCB-ECs, in which the WPCBs was first heated with an infra-red heater in the disassembly module, then ECs were swept off from the base board by rotating steel brush rods. (Chen et al (2013)) proposed a technology of using hot air to melt electronic components from the base boards. The best automatic heated-air disassembly efficiency was accomplished when the preheating temperature and heating source temperature were 120°C and 260°C, respectively, and the incubation period was 2 min.…”