A review and environmental impact analysis on the current state of froth flotation on recycling of e-wastes

The current recycling methods to recover metal contents from electronic wastes (e-wastes) are primarily chemical based, such as hydrometallurgy, pyrometallurgy. These methods typically do not involve pretreatments to remove non-metallic components, which causes increasing reagent and energy consumption, and greenhouse gas emission during recycling. Mechanical methods exploiting differences in material properties, such as gravity, magnetic, electrostatic, can achieve pre-treatment which receive increasing attention. Amongst different mechanical methods, froth flotation utilizing surface hydrophobicity to achieve the desired separation appears to receive less attention but can be very promising to recycle a variety of e-wastes. In this work, the challenges and advances in the recovery of metals from three main e-wastes, including spent lithium-ion batteries (S-LIBs), waste printed circuit boards (WPCBs), and spent photovoltaic solar panels (S-PVs), using flotation were reviewed. The work also conducted a life cycle analysis to assess the environmental impact of flotation in recycling these e-wastes. According to TRACI standards, flotation reagents have the highest environmental impact compared to electricity and water consumption. The study suggests that flotation can serve as an effective pre-treatment operation prior to the chemical treatment to improve the overall the e-waste recycling but future research is still needed.