A thermodynamic-based life cycle assessment of precious metal recycling out of waste printed circuit board through secondary copper smelting

Abstract

This study provides an environmental impact assessment of the black copper smelting route for the processing and recovery of copper and other valuable metals such as gold and silver from waste printed circuit boards (PCB). Thermodynamic based analysis was conducted to simulate the recycling process and a life cycle assessment was carried out to estimate and compare the environmental impact of the two scenarios: (1) recycling of precious metal out of waste PCBs through secondary copper smelting (Electronic Waste Processing, EWP); and (2) secondary copper recycling without adding electronic waste to the feed (SCR). The results of the study revealed that environmental impacts of using e-waste along with low-grade copper scrap in existing smelters to recover precious metals are dependent on the distance the material feed travels to the smelter and the means of electricity supplying the smelter. It is also found that the impact of the EWP scenario for climate change, freshwater eutrophication, and fossil depletion is significantly higher than those obtained from the SCR scenario and it is mainly because the metal and oxide dust in former scenario needs to be further refined to recover metals such as nickel, zinc and lead. The results also confirm that 10% cut in electricity usage in EWP scenario, has the higher environmental benefit in almost all dominant categories.