Combination of Pyrolysis and Physical Separation to Recover Copper and Tin from Waste Printed Circuit Boards
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https://doi.org/10.1007/s11837-020-04135-2 Ó 2020 The Minerals, Metals & Materials Society
THERMODYNAMIC MODELING OF SUSTAINABLE NON-FERROUS METALS PRODUCTION
Combination of Pyrolysis and Physical Separation to Recover Copper and Tin from Waste Printed Circuit Boards XUN WANG,1 FEN JIAO,1,2 WENQING QIN,1,2 ZIHAN LI,1 NA WANG,1 WEI LIU,1,2,3 and CONGREN YANG1,2,4 1.—School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China. 2.—Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China. 3.—e-mail: [email protected]. 4.—e-mail: yangcongren@ csu.edu.cn
Waste printed circuit boards (WPCBs) are an essential component in electronic waste (e-waste), and contain a number of valuable metals (e.g., Cu, Sn) as well as non-metal resources (e.g., brominated epoxy resin). Currently, most of the non-metals are disposed of in landfills, causing environmental problems. In this study, a combination of pyrolysis and physical separation is proposed to recover valuable resources, including both metals and non-metals, from WPCBs. The WPCBs were pyrolyzed at 700°C under a nitrogen atmosphere. Pyrolysis oil and gas can be reused as fuel for the pyrolysis of WPCBs. Metals like copper, tin, and iron in the pyrolysis residues were separated by selective crushing, sieving, gravity separation, and magnetic separation. Finally, rich copper (Cu 82.21%, Sn 1.47%), rich tin (Cu 53.20%, Sn 13.43%), rich iron (Fe > 63%), and non-metal products were obtained, and the total recoveries of copper, tin, and iron were 95%, 86%, and 76%, respectively.
INTRODUCTION Since the beginning of the twenty-first century, the rapid development and innovation of electronic technology has accelerated the speed of electronic product replacement. Electronic waste (e-waste), one of the fastest-growing waste categories, is increasing by 3–5% a year worldwide. The United Nations University predicts that e-waste production will reach 50 million tons by 2020.1 As an important part of e-waste, waste printed circuit boards (WPCBs) account for 6% of e-waste,2 and they contain many toxic substances, like lead, chromium, cadmium, mercury, and brominated flame retardants (BFRs).1,3,4 The heavy metal and persistent organic pollutants released into the environment during the informal recycling of WPCBs have caused serious environmental problems.5–7 Nevertheless, WPCBs also contain large amounts of valuable resources. A typical computer printed circuit board consists of 27% polymer, 28% ceramic, and 45% metals.8 The valuable metals in WPCBs are mainly copper, tin, gold, silver, palladium, etc., where copper accounts for more than 20%.9,10 In
WPCBs, especially, the precious metal content is much higher than in raw ore.11 Therefore, it is necessary to realize efficient and environmentally friendly recycling of WPCBs.12,13 In the past few years, the non-metallic components of WPCBs have mainly been landfilled or burned.14 With the imp
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