Separation of metals from Ni-Cu-Ag-Pd-Bi-Sn multi-metal system of e-waste by leaching and stepwise potential-controlled electrodeposition

• Published in: Journal of hazardous materials 2021-04, Vol.408, p.124772, Article 124772
• Main Authors: Liu, Ya, Song, Qingming, Zhang, Lingen, Xu, Zhenming
• Format: Article
• Language: English
• Subjects: E-waste; Leaching; Metals; Potential-controlled electrodeposition
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.124772

Electronic waste, as hazardous waste, contains a large amount of metals, which is of great recovery value. However, they are difficult to separate due to wide variety and complex distribution. Most of current recycling methods are environmentally-unfriendly or complicated. In this study, a simple, efficient and green approach for metals separation from Ni-Cu-Ag-Pd-Bi-Sn multi-metal system of e-waste was proposed combining mild leaching and stepwise potential-controlled electrodeposition. The leaching efficiencies of Ni, Ag, Pd, Cu and Bi were 99.16%, 99.09%, 94.91%, 99.61% and 23.76% with 1 mol/L HNO3 at 80 °C. The leaching process was analyzed. It showed that the existence of Ag-Pd continuous solid solution in the alloy lowered the oxidation potential of Pd, which facilitated its leaching. Sn precipitated as SnO2. Then Ag-Pd alloy and Cu-Bi alloy were separately extracted from the leaching solution by stepwise electrodeposition. 97.72% of Ag and 98.05% of Pd were recycled after 5 h with potential of 0.35 V. The recovery efficiencies of Cu and Bi were 97.87% and 97.33% after 7 h with potential of 0.05 V. The EDS results showed high purity property of Ag-Pd and Cu-Bi alloy. This process can achieve cleaner and efficient extraction of metals from multi-metal system in e-waste. [Display omitted] •Precious metal alloy from e-waste was leached out with mild acid and the leaching process was analyzed.•Stepwise electrodeposition was applied to selectively extract Ag-Pd alloy and Cu-Bi alloy from the leaching solution.•An efficient and cleaner process for recovering metals from multi-metal system of e-waste was proposed.