RECYCLING SILICON AND SILICON COMPOUNDS Physical Processing of Discarded Integrated Circuits for Recovery of Metallic Values AMIT BARNWAL 1 and NIKHIL DHAWAN 1,2 1.—Department of Metallurgical & Materials Engineering, Indian Institute of Technology, IIT-Roorkee, Roorkee, Uttarakhand 247667, India. 2.—e-mail: ndhawan.fmt@iitr.ac.in Recycling of discarded integrated circuits is an important issue related to waste management, resource conservation, and metal recovery aspects. In this study, physical processing comprising water fluidization, magnetic separation, and density separation of discarded units was followed to recover Cu, Fe, Ni, and Si values. The fluidization technique provided an enriched metal con- centrate comprising 53.05% Cu, 16.2% Fe, and 10.5% Ni in the underflow fraction, and the overflow fraction comprised 63.1% Si with 17.8% C. High metallic dissolution was attained for the processed samples compared with the feed leaching because of effective separation of the non-metallic fraction during physical processing. Overall, 1 kg of discarded ICs yielded  120 g ferrous metal with  57.4% Fe and  26% Ni purity and  390 g metallic values with 85% Cu and  490 g non-metallic values with  84% Si. INTRODUCTION The global production of electronic devices is increasing continuously because of technological modernization and lifestyle changes. Integrated circuits (ICs) are constructed as complex circuits on a semiconductor wafer made up of silicon con- nected with metallic parts, which may contain numerous tiny resistors, capacitors, and transistors. Recovery of metals from printed circuit boards (PCBs) has been extensively reported; however, recycling of the electronic components such as integrated circuits (ICs) is rarely reported. The global market value of ICs was $43,240 million in 2017 and will double by 2025. 1 ICs are mainly molded with epoxy resin, silica particle filler, and additives because of their high thermal resistance and good insulating properties. 2 Recovery of metals from electronic waste includes physical separation followed by pyrometallurgy and hydrometallurgical processes. The recovery of met- als from discarded ICs was reported using vacuum pyrolysis after the degradation of organic material. 3 The pyro-hydro hybrid metallurgical process involves pyrolysis at 300–400°C and leaching of the obtained poly-cracked ash in different acids followed by solvent extraction for the metal recovery from the discarded PCBs. The pyro-hydro hybrid metallurgical process, i.e., pyrolysis at 300–400°C and leaching followed by solvent extraction, is frequently reported . 4 A major disadvantage of pyrometallurgical treatment is the release of toxic gases such as methane, carbon monoxide, carbon dioxide, and dioxin-furans. 5–7 Smelting of electronic waste at high temperature yields high copper recovery, but often produces slag and sludge com- prising a mixture of different metals. Both physical and chemical methods have been adopted for the recovery of Cu and Fe values using selective leach- ing. 8 There is a significant density difference between metal and plastic values, and this is a driving force behind the application of gravity separation methods such as jigging and fluidiza- tion. 8,9 Air classification and vibration-assisted gas– solid fluidized beds are used for the separation based on their differences in size and density. 10–12 It is economically rewarding to recover metals as the metallic content in electronic waste is at least ten times more than in their natural ores. 8 It is envisaged that the effective separation of plastics and metals before hydrometallurgical or pyrometallurgical processing can significantly reduce acid consumption, leach residue generation, slag generation, and multiple processing steps. In this study, an attempt is made to physically sepa- rate metallic and silica values from discarded ICs prior to hydrometallurgical processing. To the best of the authors’ knowledge, this study is among the JOM https://doi.org/10.1007/s11837-020-04137-0 Ó 2020 The Minerals, Metals & Materials Society