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S.c. Tang - One of the best experts on this subject based on the ideXlab platform.

B. K. Mishra - One of the best experts on this subject based on the ideXlab platform.

  • waste Printed Circuit boards recycling an extensive assessment of current status
    Journal of Cleaner Production, 2015
    Co-Authors: Pankaj Ku Parhi, B. K. Mishra, M K Ghosh, P. S. Mukherjee, B. Ghosh
    Abstract:

    Abstract The rapid proliferation of electronic devices in the last two decades has compelled the researchers to find a remedy for one of the most toxic and hazardous waste materials – the waste Printed Circuit Boards. Numerous articles have been published demonstrating the process routes for recycling of this toxic but otherwise useful waste due to nearly 30% metal content. In this paper, more than 150 related articles mostly published in the last 15 years and covering the broad areas like characterization of waste Printed Circuit Boards, health hazards associated with the processing and the different routes of recycling have been analyzed to provide a comprehensive overview on this topic. Physical separation processes employing electrostatic separator, magnetic separator, froth floatation, etc., has been reviewed for separation of metals and non-metals, along with useful utilizations of the non-metallic materials. The recovery of metals from this waste material through pyrometallurgical, hydrometallurgical or bio-hydrometallurgical routes is also critically discussed.

Paul T. Williams - One of the best experts on this subject based on the ideXlab platform.

  • Chemical Recycling of Printed Circuit Board Waste by Depolymerization in Sub- and Supercritical Solvents
    Waste and Biomass Valorization, 2015
    Co-Authors: Eyup Yildirir, Jude A Onwudili, Paul T. Williams
    Abstract:

    Disposal of waste Printed Circuit boards is regarded as a potential major environmental problem due to their heavy metal content. Therefore, recycling waste Printed Circuit boards represents an opportunity to recover the high value resin chemicals and the high value metals that are present. In this study, the solvo-thermal depolymerisation of waste Printed Circuit boards obtained from desktop computer monitors was carried out using water, ethanol and acetone between 300 and 400 °C. Alkalis (NaOH, KOH) were used as additives to promote the removal of the resin fraction of the Printed Circuit boards. At 400 °C, 94 % resin removal was achieved when water was used as the solvent, in the presence of NaOH. The liquid produced in the process was analysed by GC/MS and the results showed that it was mainly composed of phenol, and some phenolic compounds, with up to 62.5 wt% present as phenol in the liquid phase.

  • valorization of Printed Circuit boards from waste electrical and electronic equipment by pyrolysis
    Waste and Biomass Valorization, 2010
    Co-Authors: Paul T. Williams
    Abstract:

    Waste electrical and electronic equipment waste generated in the European Union (EU27) has been identified as one of the fastest growing waste streams in the EU, such that by 2020 annual arisings of waste electrical and electronic equipment will be 12.3 million tonnes. The EU have introduced the Waste Electrical and Electronic Equipment (WEEE) Directive which aims to promote the re-use, recycling and other forms of recovery of electrical and electronic waste. Printed Circuit boards represent a particular category of WEEE that has attracted wide attention for treatment by pyrolysis technology. Printed Circuit boards are composed of mainly a glass fibre reinforced polymer resin board onto which are manufactured components containing a wide variety of metals such as copper, iron, tin and lead. But also a range of very high value metals including gold, silver, and palladium. In this paper, the use of pyrolysis to treat waste Printed Circuit boards as a means to recover valuable materials, including the metals, an oil and gas product from the polymeric resin and glass fibre is reviewed.

  • SEPARATION AND RECOVERY OF MATERIALS FROM SCRAP Printed Circuit BOARDS
    Resources Conservation and Recycling, 2007
    Co-Authors: William J. Hall, Paul T. Williams
    Abstract:

    Abstract Printed Circuit boards from waste computers, televisions, and mobile phones were pyrolysed in a fixed bed reactor with the aim of separating and recovering the organic and metallic materials. A selection of Printed Circuit boards from each of the three waste classes was pyrolysed at 800 °C and the pyrolysis products were analysed using GC-FID, GC-TCD, GC-MS, GC-ECD, ICP-MS, and SEM-EDX. The pyrolysis oils contained high concentrations of phenol, 4-(1-methylethyl)phenol, and p -hydroxyphenol, as well as bisphenol A, tetrabromobisphenol A, methyl phenols, and bromophenols. The pyrolysis oils also contained significant concentrations of organo-phosphate compounds and a number of tetrabromobisphenol A pyrolysis products were also identified. The pyrolysis residues were very friable and the organic, glass fibre, and metallic fractions could easily be separated and the electrical components could easily be removed from the remains of the Printed Circuit boards. The ash in the residue mainly consisted of copper, calcium, iron, nickel, zinc, and aluminium, as well as lower concentrations of valuable metals such as gallium, bismuth, silver, and gold, silver was present in particularly high concentrations. Many other metals were also identified in the ash by ICP-MS and SEM EDX. The pyrolysis gases mainly consisted of CO 2 and CO but all of the C 1 –C 4 alkanes and alkenes were present, as were some inorganic halogens.

H.s.h. Chung - One of the best experts on this subject based on the ideXlab platform.

  • characterization of coreless Printed Circuit board pcb transformers
    IEEE Transactions on Power Electronics, 2000
    Co-Authors: S.c. Tang, S. Y. Hui, H.s.h. Chung
    Abstract:

    In this paper, coreless Printed-Circuit-board transformers are characterized. A range of coreless Printed Circuit board (PCB) transformers with different geometric parameters have been fabricated and tested. Based on a recently reported analytic method, the self inductance of these transformers is calculated. This analytical method is also extended to cover the prediction of the transformers' mutual inductance. All calculated parameters have been confirmed with measurements for the frequency range from 100 kHz to 30 MHz. These results provide useful information for the optimal design of coreless PCB transformers.

Fushen Zhang - One of the best experts on this subject based on the ideXlab platform.

  • high copper recovery from scrap Printed Circuit boards using poly ethylene glycol sodium hydroxide treatment
    Environmental Chemistry Letters, 2018
    Co-Authors: Congcong Zhang, Fushen Zhang
    Abstract:

    Recycling scrap Printed Circuit boards for recovery of valuable metal resources is a major environmental issue. Most available disposal technologies are not environmentally safe. Here, Printed Circuit board particles were subjected to solvothermal treatment using poly(ethylene glycol)/sodium hydroxide. Results show that residual ratio of bromine varied with temperature, treating time and sodium hydroxide addition. The optimal temperature, treating time and sodium hydroxide addition were 180 °C, 10 h and 0.4 g, with the lowest residual bromine ratio of 1.7%. After treatment, the separation of residue was done by gravity separation and the purity of copper in the recovered metallic components was 97.8%. The recyclability of scrap Printed Circuit boards before crushing was also compared, the residue of which yielded a complete separation of copper foils and glass fibers. The purity of copper in the foil was achieved at 96.6%. We conclude that this novel process represents an applicable way to recycle high value resources from scrap Printed Circuit boards.

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