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<p>Every year, millions of tons of electronic waste (e-waste) are discarded, with most of it ending up in landfills. Printed circuit boards (PCBs) are among the most commonly used and valuable components in waste electrical and electronic equipment. Pyrometallurgical processes are commonly used as a first step to separate metallics from waste printed circuit boards (WPCB). Preliminary work presented here shows that low temperature separation of metallics from WPCB via melting is hindered by the high melting point of fiberglass used as a structural material. Current work includes physical and chemical separation of surface mounted devices from WPCB, followed by pyrometallurgical treatment. Pyrolysis of WPCB was performed at 800&#xa0;℃ under the argon atmosphere. We report separation of about 60% of metallics present just after pyrolysis. In order to smelt the remaining pyrolyzed mass, a CaO–SiO<sub>2</sub>–FeO–B<sub>2</sub>O<sub>3</sub> flux was designed such that complete melting of the&#xa0;pyrolyzed residue of WPCB is achieved at a temperature of 1200&#xa0;℃. FactSage software (FToxid and FactPS databases were used) was used to calculate the melting behavior and viscosity of the flux and expected slag composition. The smelting operation successfully recovered the&#xa0;remaining 40% of metallics in WPCB. The concentrations of tin and silver in the metal obtained from pyrolysis and pyrolysis + smelting routes were approximately 10% and 1750&#xa0;ppm of Sn, and 980&#xa0;ppm and 140&#xa0;ppm of Ag, respectively. However, iron pickup from slag to metal was observed during the smelting experiment, likely due to the&#xa0;reduction of FeO from slag by char residue in the pyrolyzed WPCB.</p> Graphical Abstract <p></p>

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Pyrometallurgical Recovery of Metallics from Waste Printed Circuit Boards at Low Temperatures

  • 期刊论文

  • 发表日期：

    2025年5月6日

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  • Santhosh Banoth,
  • Chandu Soren,
  • Durgapraveen Bavana,
  • Sai Prakash Sunkavalli,
  • Sudhanshu Mallick,
  • Deepoo Kumar

摘要

Every year, millions of tons of electronic waste (e-waste) are discarded, with most of it ending up in landfills. Printed circuit boards (PCBs) are among the most commonly used and valuable components in waste electrical and electronic equipment. Pyrometallurgical processes are commonly used as a first step to separate metallics from waste printed circuit boards (WPCB). Preliminary work presented here shows that low temperature separation of metallics from WPCB via melting is hindered by the high melting point of fiberglass used as a structural material. Current work includes physical and chemical separation of surface mounted devices from WPCB, followed by pyrometallurgical treatment. Pyrolysis of WPCB was performed at 800 ℃ under the argon atmosphere. We report separation of about 60% of metallics present just after pyrolysis. In order to smelt the remaining pyrolyzed mass, a CaO–SiO2–FeO–B2O3 flux was designed such that complete melting of the pyrolyzed residue of WPCB is achieved at a temperature of 1200 ℃. FactSage software (FToxid and FactPS databases were used) was used to calculate the melting behavior and viscosity of the flux and expected slag composition. The smelting operation successfully recovered the remaining 40% of metallics in WPCB. The concentrations of tin and silver in the metal obtained from pyrolysis and pyrolysis + smelting routes were approximately 10% and 1750 ppm of Sn, and 980 ppm and 140 ppm of Ag, respectively. However, iron pickup from slag to metal was observed during the smelting experiment, likely due to the reduction of FeO from slag by char residue in the pyrolyzed WPCB.

Graphical Abstract