Experimental investigation of the influence of reaction atmosphere on the pyrolysis of printed circuit boards

• Printed circuit boards (PCB) are one of the most challenging fractions of waste electrical and electronic equipment (WEEE) in terms of recycling due to their complexity and diversity. Pyrolysis seems to be a promising alternative for production of energy carriers from its organic fraction with simultaneous recovery of metals. Reaction atmosphere is among the process parameters that affects the thermal decomposition as well as the products’ formation and distribution. In this study, the decomposition of two different PCB fractions in inert and steam atmospheres has been investigated by means of thermogravimetric analysis (TGA) and lab scale fixed bed reactor experiments. It was found that the decomposition of the tested materials in steam atmosphere starts at lower temperatures and proceeds slower compared to the N2 atmosphere. Moreover, a two-step decomposition has been observed on the PCB sockets fraction due to the fact that high amount of antimony oxide was present, a common additive for improving the flame retardancy, which have been also observed on previous studies (Wu et al., 2014). The presence of steam influence the pyrolysis gas composition and promotes additional vaporisation of antimony as verified by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the liquid fraction has been qualitatively analysed using a GC/MS in order to determine the brominated compounds as well as other compounds that are produced from this process.

Ämnesord

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

Antimony

Printed circuit boards

Pyrolysis

TGA

Waste electrical and electronic equipment (WEEE)

Chemical reactors

Decomposition

Electronic equipment

Electronic Waste

Metal recovery

Oscillators (electronic)

Scanning electron microscopy

Thermogravimetric analysis

Timing circuits

X ray diffraction

Brominated compounds

Experimental investigations

Lower temperatures

Powder X ray diffraction

Printed circuit boards (PCB)

Process parameters

Reaction atmospheres

Waste electrical and electronic equipment

complexity

PCB

reaction kinetics

recycling

thermal decomposition

X-ray diffraction

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