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Printed circuit board leach residue as a reductant for pyrometallurgical operation
6th International Conference on Recycling and Waste Management
December 03-04, 2018 | Dubai, UAE
Attah-Kyei Desmond, Akdogan G, Dorfling C, Erwee M, Zietsman JH, Lindberg D and Reynolds Q
Stellenbosch University, South Africa
Posters & Accepted Abstracts : J Biotech and Phyto
Abstract:
In recent years, there has been an increase in the generation
of Waste electrical and electronic equipment (WEEE) due to
the advancement of technology. Printed circuit board (PCB) is
the main focus of electronic waste because of the inherently
high value of contained metals such as copper and gold.
Hydrometallurgical processes, consisting of several leaching
stages, are the most feasible option for the recovery of metals
from PCB waste. However, hydrometallurgy does not address
the issue of non-metallic PCB fractions that may end up being
dumped at land fill sites or incinerated. When the non-metallic
fractions are dumped, the heavy metals and the brominated
flame retardants leach into groundwater leading to secondary
pollution. Several options for treatment of the non-metallic
fraction including material recycling, where the residue may be
used as inclusions in concrete or asphalt materials with minimal
processing or chemical recycling, where chemicals and fuels are
produced from the residue using techniques such as pyrolysis
exist.
Due to the complex composition of PCB leach residue, recovery
by thermal treatment is likely to be the most feasible process
route from technical and economical perspectives. In this study,
the utilisation of the non-metallic leached PCB waste fraction
as reductant in primary metal smelting operations and solid
state pre-reduction is investigated. Analysis of the leached
residue revealed that PCB is highly amorphous and has a carbon
content of 28.5%, oxygen content of 23.1%, with the ash and
volatile matter contents being 40.1% and 44.8% respectively.
Thermodynamic modelling and laboratory-scale experiments
that simulate chromite smelting and solid state pre-reduction
operations were performed using various blends of PCB and
carbonaceous reducing agents. The models showed that PCB
residue might be used to partially replace the conventional
reductants. Preliminary investigations revealed that in chromite
smelting the optimal blend contains up to 20 wt% PCB residue,
with energy savings of 200 kWh/t of ore to achieve the same
metal recovery.
Biography:
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