The sorting of recyclates is an important step in communities where Mixed Waste Collection or Commingled Recyclable Collection are practiced. The collected recyclates need to be separated by their types before they can be sent for processing.
The typical process involved is described below.
As technology becomes more and more advanced, more steps in the process can be automated. With the use of machineries, the process can be achieved in a fraction of the time previously needed.
Removing the large objects
The commingled recyclates are first spread out. Machineries like the conveyor belt may be used.
Large pieces of cardboard or plastic bags are easily removed by hand. Removing these large objects also prevent them from jamming the machineries that may be used later down the line.
Separating the different materials
Where machines are used, the recyclates are then separated by weight.
Paper and Plastics The lighter plastics and paper are separated from the heavier metals and glass items.
The mixed paper and plastics then undergo further separation.
Cardboard is separated from the mixed paper, while the more easily recycled plastics (eg. PET and HDPE) are collected.
Where technology is applied, a spectroscopic scanner may be used to distinguish between the different types of paper and plastic based on the absorbed wavelengths. Subsequently, the different materials are diverted to the proper collection channel.
Metals As for the metals, strong magnets may be used to separate out the ferrous metals (eg. tin-plated or steel cans) from the non-ferrous ones (eg. aluminum cans).
The ferrous ones are attracted by the magnets.
The non-ferrous metals are ejected from the recyclate stream through the use of magnetic eddy currents, which are created in the non-ferrous metals by a rotating magnetic field. In the presence of a large magnetic field, the magnetic eddy current is repulsed, ejecting the non-ferrous metals like the aluminum cans.
Glass Finally, glass is categorized based on their colors, ie. brown, amber, green or clear.
Next steps in the recycling process
After the recyclates are split out based on their types, they can be sent for processing, ie. broken down into their elements to produce raw materials for manufacturing new products.
Read more about the processing for different types of materials.
Also, read about the complete recycling process, as well as the factors that will determine the sustainability of the recycling industry.
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