How to efficient and high-value recycling of electronic components mounted on waste printed circuit boards: Recent progress, challenge, and future perspectives

The recycling of waste printed circuit boards (WPCBs) has attracted global attention because of their increasingly huge quantity, hazardous character, and high recovery values. There are plenty of reviews about the recycling of baseboards. In addition to basal boards, various and hundreds of electronic components (ECs) are mounted on the surface of WPCBs. Almost precious metals (gold and tantalum, etc.) are enriched in ECs. Meanwhile, the more hazardous organics (electrolytes, etc.) make the recycling of waste ECs a challenge. Increasing studies have focused on waste ECs recycling. However, few timely reviews summarized the recent progress, challenge, and future perspectives. Moreover, how to efficient and high-value recycling of ECs has not well been revealed. Herein, this review in-depth analyzed and discussed the recycling of waste ECs mounted on the surface of WPCBs including: dismantling, pollutant release and treatment, classification, resource recovery, and high-value utilization. Besides the traditional dismantling process, we introduce the application of emerging artificial intelligence and machine learning. The release rules of pollutants are revealed and their treatment are described. Moreover, the hydrometallurgy and pyrometallurgy processes for resource recovery from various waste ECs are summarized. Particularly, a new idea of high-value utilization waste ECs as catalysts is also highlighted. The technologies' advantages and disadvantages are illustrated and indicate which processes are promising for industrialized applications. Finally, the challenges in waste ECs recycling are analyzed and future perspectives are proposed. This comprehensive review article reveals the research gap in waste ECs recycling, which contributes to guiding waste ECs recycling towards more efficient and high-value.