5.4 E-Waste Recycling
131
and formally. Informal recycling of the e-waste includes simply burning the devices
to melt the non-valuable materials and recover the metals such as gold. This form of
recycling is usually practiced in developing countries, mostly in Asia [3]. The workers
in these countries are unaware of the dangers associated with the materials exposed to,
posing several health issues as discussed previously. Formal recycling is performed
in recycling facilities and involves multiple processes of sorting, separation, dismantling, metallic and non-metallic separation, and refining, etc. The recycling stages
vary from a treatment facility to another but in general, the process consists of the
following basic steps [9–11]:
1 Collection: E-waste is picked up informally by waste pickers or formally
through the take-back programs by retails and manufacturers, municipal drop-off
collection centers, non-profit and for-profit collection programs.
2 Sorting, separation and material disassembly: When e-waste is at the recycling
site, it is manually sorted to remove the toxic components such as batteries, UPS
battery systems, Freon and toner cartridges that should not be crushed and require
special treatments. Precious components such as printed wiring boards are also
removed. The devices are separated into materials, primary metals, glass and
plastic, for end-processing.
3 Size reduction: After initial sorting, the waste materials are then transformed
into more homogeneous groups by size reduction either manually or mechanically or with a combination of both. Manual size reduction involves using
screwdrivers, hammers and labeled containers, while mechanical size reduction
involves conveyor belts and shredders.
4 Metallic and non-metallic separation: Steel and iron pieces are removed from
the shredded materials by magnets. Then other metals such as aluminum, copper
and brass are separated from glass and plastic using Eddy currents and density
separation.
5 Refining process: This stage is performed either by using chemicals, heat or by
metallurgical processes. Certain types of materials are recovered and returned as
the secondary raw materials for further use.
6 Disposal: Other materials that cannot be utilized are either incinerated or disposed
into landfills.
Since the electronic products have different composition and structure, it is challenging to develop an advanced recycling technology that could be effective for all
types of e-waste. There are not many recycling facilities specialized for the recovery
of a specific material and the existing facilities generally accept all types of e-waste,
which lowers the efficiency of the recycling process [11].
5.5 Recovery of Metals from E-Waste
Recovery of metals from e-waste is not just an environmental need to remove the
toxic materials such as heavy metals, but an opportunity to recycle the valuable
131
and formally. Informal recycling of the e-waste includes simply burning the devices
to melt the non-valuable materials and recover the metals such as gold. This form of
recycling is usually practiced in developing countries, mostly in Asia [3]. The workers
in these countries are unaware of the dangers associated with the materials exposed to,
posing several health issues as discussed previously. Formal recycling is performed
in recycling facilities and involves multiple processes of sorting, separation, dismantling, metallic and non-metallic separation, and refining, etc. The recycling stages
vary from a treatment facility to another but in general, the process consists of the
following basic steps [9–11]:
1 Collection: E-waste is picked up informally by waste pickers or formally
through the take-back programs by retails and manufacturers, municipal drop-off
collection centers, non-profit and for-profit collection programs.
2 Sorting, separation and material disassembly: When e-waste is at the recycling
site, it is manually sorted to remove the toxic components such as batteries, UPS
battery systems, Freon and toner cartridges that should not be crushed and require
special treatments. Precious components such as printed wiring boards are also
removed. The devices are separated into materials, primary metals, glass and
plastic, for end-processing.
3 Size reduction: After initial sorting, the waste materials are then transformed
into more homogeneous groups by size reduction either manually or mechanically or with a combination of both. Manual size reduction involves using
screwdrivers, hammers and labeled containers, while mechanical size reduction
involves conveyor belts and shredders.
4 Metallic and non-metallic separation: Steel and iron pieces are removed from
the shredded materials by magnets. Then other metals such as aluminum, copper
and brass are separated from glass and plastic using Eddy currents and density
separation.
5 Refining process: This stage is performed either by using chemicals, heat or by
metallurgical processes. Certain types of materials are recovered and returned as
the secondary raw materials for further use.
6 Disposal: Other materials that cannot be utilized are either incinerated or disposed
into landfills.
Since the electronic products have different composition and structure, it is challenging to develop an advanced recycling technology that could be effective for all
types of e-waste. There are not many recycling facilities specialized for the recovery
of a specific material and the existing facilities generally accept all types of e-waste,
which lowers the efficiency of the recycling process [11].
5.5 Recovery of Metals from E-Waste
Recovery of metals from e-waste is not just an environmental need to remove the
toxic materials such as heavy metals, but an opportunity to recycle the valuable