Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process

Xiu, Fu-Rong; Qi, Yingying; Zhang, Fu-Shen

doi:10.1016/j.wasman.2013.01.023

Cited by 102 publications

(48 citation statements)

References 27 publications

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“…However, the toxic organic matters such as BFRs in waste PCBs cannot be removed efficiently during such processes above mentioned Vermaak, 2007, 2009). Chien et al (2000) firstly proposed the use of supercritical water oxidation (SCWO) as the pre-treatment technology for waste PCBs, and toxic organic matters such as BFRs in waste PCBs could be degraded efficiently in SCWO process (Xiu and Zhang, 2012;Xiu et al, 2013Xiu et al, , 2014. Hence, the decomposition of toxic organic matters and the enrichment of metals could be achieved at the same time by using SCWO as a pre-treatment technique for subsequent hydrometallurgical process.…”

Section: Introductionmentioning

confidence: 99%

Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

2015

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a b s t r a c tPrecious metals are the most attractive resources in waste printed circuit boards (PCBs) of mobile phones. In this work, an alternative process for recovering Au, Ag, and Pd from waste PCBs of mobile phones by supercritical water oxidation (SCWO) pre-treatment combined with iodine-iodide leaching process was developed. In the process, the waste PCBs of mobile phones were pre-treated in supercritical water, then a diluted hydrochloric acid leaching (HL) process was used to recovery the Cu, whose leaching efficiency was approximately 100%, finally the resulting residue was subjected to the iodine-iodide leaching process for recovering the Au, Ag, and Pd. Experimental results indicated that SCWO pre-treatment temperature, time, and pressure had significant influence on the Au, Ag, and Pd leaching from (SCWO + HL)-treated waste PCBs. The optimal SCWO pre-treatment conditions were 420°C and 60 min for Au and Pd, and 410°C and 30 min for Ag. The optimum dissolution parameters for Au, Pd, and Ag in (SCWO + HL)-treated PCBs with iodine-iodide system were leaching time of 120 min (90 min for Ag), iodine/iodide mole ratio of 1:5 (1:6 for Ag), solid-to-liquid ratio (S/L) of 1:10 g/mL (1:8 g/mL for Ag), and pH of 9, respectively. It is believed that the process developed in this study is environment friendly for the recovery of Au, Ag, and Pd from waste PCBs of mobile phones by SCWO pre-treatment combined with iodine-iodide leaching process.

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Section: Introductionmentioning

confidence: 99%

Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

2015

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“…Meanwhile, the BFRs contained in waste PCBs can be removed safely during the co-treatment. Hence, the dechlorination of PVC, the debromination of BFRs, and the leaching of metals would occur in the same reaction system, which is quite different from the process in our previous report [24]. During the co-treatment system, the characteristics and influence factors of dechlorination, debromination, and metals leaching are needed to be clarified.…”

Section: Introductionmentioning

confidence: 63%

“…In our latest study [24], a two-step process for metals recovery from waste PCBs by supercritical water pre-treatment combined with acid leaching was developed. In the proposed process, waste PCBs were pre-treated by supercritical water, then the separated solid phase product with concentrated metals was subjected to an acid leaching process for metals recovery.…”

Section: Introductionmentioning

confidence: 99%

Co-treatment of waste printed circuit boards and polyvinyl chloride by subcritical water oxidation: Removal of brominated flame retardants and recovery of Cu and Pb

Xiu

Zhang

2014

Chemical Engineering Journal

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h i g h l i g h t sWe report an effective process for co-treatment of waste PCBs and PVC. Brominated flame retardants can be decomposed efficiently in co-treatment. Dechlorination of PVC was complete and safe. Cu and Pb in waste printed circuit boards can be recovered efficiently. Sn and Cr can be immobilized efficiently in the residue after co-treatment. t r a c tIn this work, an effective process for removal of brominated flame retardants (BFRs) and recovery of Cu and Pb from waste printed circuit boards (PCBs) was developed. In the process, waste PCBs and polyvinyl chloride (PVC) were co-treated by subcritical water oxidation (SBWO). PVC was used as a hydrochloric acid source and waste PCBs was used as a neutralizing reagent for the produced HCl. The dechlorination of PVC, removal of BFRs, and recovery of Cu and Pb could be achieved simultaneously by the one-step SBWO reaction. Experimental results showed that the dechlorination of PVC was complete when SBWO temperature exceeded 250°C. SBWO co-treatment was high efficient for the leaching of Cu and Pb from waste PCBs, and XRD spectra indicated that Sn was immobilized as SnO 2 in the residue after co-treatment. The optimum SBWO co-treatment conditions were temperature of 350°C, time of 60 min, solidliquid ratio of 1:9 g/ml, and PVC-to-PCBs ratio of 1:1, respectively. In the optimized co-treatment, 98.9% of Cu and 80% of Pb were recovered, while the leaching efficiencies of Sn and Cr were 15.3% and 3.9%, respectively. Meanwhile, approximately 100% of the bromine was changed into HBr and enriched in water after co-treatment.

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“…The proposed technologies include mainly pyrometallurgy (Cayumil et al, 2014;Flandinet et al, 2012), hydrometallurgy (Fogarasi et al, 2015;Tuncuk et al, 2012;Birloaga et al, 2014), bio-technology (Rodrigues et al, 2015;Pant et al, 2012;Zhu et al, 2011), and mechanical methods (Chao et al, 2011;Duan et al, 2009). Among these technologies, hydrometallurgical processes with relatively low capital costs, no gas/dust formation, operational selectivity and suitability for small scale applications are propitious alternatives for the treatment of waste PCBs (Birloaga et al, 2013;Xiu et al, 2013). However, most of the hydrometallurgical processes mainly focused on the leaching of copper.…”

Section: Introductionmentioning

confidence: 99%

A novel recovery method of copper from waste printed circuit boards by supercritical methanol process: Preparation of ultrafine copper materials

Xiu

Weng

et al. 2017

Waste Management

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a b s t r a c tIn this study, supercritical methanol (SCM) process was successfully used for the preparation of ultrafine copper materials from waste printed circuit boards (PCBs) after nitric acid pretreatment. Waste PCBs were pretreated twice in nitric acid. Sn and Pb were recovered by the first nitric acid pretreatment. The leach liquor with a high concentration of copper ions after the second nitric acid leaching was subjected to SCM process. The mixture of Cu and Cu 2 O with poor uniformity of particle size was formed due to the effect of ferric iron contained in the leach liquor of waste PCBs, while more uniform and spherical Cu particles with high monodispersity and smaller size could be prepared after the removal of Fe. The size of Cu particles increased obviously with the decline of SCM temperature, and particles became highly aggregated when the reaction temperature decreased to 300°C. The size of Cu particles decreased markedly with the decrease of initial concentration of copper ion in the leach liquor of waste PCBs. It is believed that the process developed in this study is simple and practical for the preparation of ultrafine copper materials from waste PCBs with the aim of recycling these waste resources as a high value-added product.

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Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process

Cited by 102 publications

References 27 publications

Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

Leaching of Au, Ag, and Pd from waste printed circuit boards of mobile phone by iodide lixiviant after supercritical water pre-treatment

Co-treatment of waste printed circuit boards and polyvinyl chloride by subcritical water oxidation: Removal of brominated flame retardants and recovery of Cu and Pb

A novel recovery method of copper from waste printed circuit boards by supercritical methanol process: Preparation of ultrafine copper materials

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