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Comparative life cycle analysis for value recovery of precious metals and rare earth elements from electronic waste

Li, Zhen, Diaz, Luis A., Yang, Zhiyao, Jin, Hongyue, Lister, Tedd E., Vahidi, Ehsan, Zhao, Fu
Resources, conservation, and recycling 2019 v.149 pp. 20-30
copper, ecological footprint, electrochemistry, electronic wastes, energy, hydrochloric acid, hydrogen peroxide, laws and regulations, life cycle assessment, oxidants, rare earth elements, recycling
There is an ever-increasing concern regarding the electronic waste (e-waste), which is the fastest growing waste stream in the world. Incentivized by various legislations and the intrinsic value of critical metals inside, recycling of e-waste is becoming an attractive business opportunity that also benefits the environment. A novel electrochemical recovery (ER) process has been developed as a promising alternative to the existing pyrometallurgical and hydrometallurgical processes based technologies to recover base metals, precious metals, and rare earth elements (REEs) from e-waste. Experimental results indicate that the ER process has lower chemical consumption, enhanced control, and reduced energy demand compared to the pyrometallurgical and the hydrometallurgical processes. To quantify and compare the environmental performances of the three technologies, life cycle analysis has been conducted. Results show that the ER process outperforms the other two processes in almost all impact categories adopted in TRACI and ILCD while there is no clear winner between the hydrometallurgical and the pyrometallurgical processes. The highest impactful input for the ER method is hydrochloric acid, and for the pyrometallurgical method is copper scrap, while for the hydrometallurgical method, it is hydrogen peroxide, an oxidizer that accelerates base metal extraction process, that dominates the overall environmental footprint. The environmental viability of the ER process warrants the further development of ER process at industrial scale.