Plastics pose a threat to ecosystems, especially in the marine ecosystem. Plastic seas are becoming increasingly common, and this is where the bulk of this waste is deposited. Therefore, reducing the consumption of packaging, using recyclable bags and recycling plastic is essential. In this post we tell you about the plastic recycling process.
Plastic recycling process
As with scrap materials such as recycled glass or paper and cardboard, there are several stages in the recycling process.
Deposit of packaging
The process always begins with the deposit of plastic packaging and other derived materials in the yellow bin. The work of the public and industry is essential for this.
Receipt of material
At this point, all plastic material that can be recycled arrives at the recycling plant. To do this, the plastic codes are checked, as not all of them can be recycled. In this case, it would be HDPE plastic, LDPE plastic, PP plastic, PET plastic, PS plastic or ABS plastic, among others. This material must be pre-sorted by quality and can come from industrial, post-consumer and agricultural rejects.
They usually arrive at the recycling plant in boxes, sacks, Big Bags, shredded, in containers (bulk) or in bales.
Sorting process
After the plastic material has been received, it undergoes a rigorous sorting process which is divided into the following phases:
Colour segregation of the plastic
In this phase, a lower consumption of dyes is achieved, which gives a greater benefit both economically and environmentally, as well as obtaining a wider range of finished products offering different ranges of colours.
Separation of unsuitable materials
This process separates plastic materials other than those which at the time of consumption correspond to the quality in process, labels, ferrous materials or soil. This ensures optimum quality, increases production capacities and avoids inefficient production.
Shredding
At this stage, all plastic material is broken up and shredded into very small pieces, known as chippings, to facilitate further processing. They are shredded through high production capacity shredders, by means of a set of rotating blades, in order to achieve a homogeneous granulometry of the plastic.
Washing
Once the plastic has been converted into pellets, it is introduced into industrial washers. The blades are responsible for removing the water so that the pellets are completely wet, leaving any impurities such as dirt, cardboard or metals at the bottom.
Drying and centrifuging
The material resulting from the previous step passes to the centrifuges where, in addition to drying, any remaining impurities are completely removed.
Homogenisation
After passing through the processes of shredding, washing and drying, the plastic is compacted through a mechanical process, in order to have a uniform colour and texture, and is stored.
Plastic recycling
There are two forms of plastic recycling process:
Mechanical recycling
In mechanical recycling we have the following steps or phases.
- Extrusion. The central body of the extruder consists of a long barrel which, through the heat and friction of its inner shaft, allows the plasticising of all the particles previously created, giving rise to a uniform mass. Thus, the polymers are melted by heat. This is when the desired colour is added.
- Filtering. After extrusion, the plastic goes through a filtering process, where very fine meshes retain all the impurities that may have been left over from the previous processes.
- Pelleting. In the pelletising process, the plastic comes out of the head of the extruder in the form of threads that are deposited in water to cool down. From there, they are cut to obtain the appropriate grain.
Chemical recycling
In chemical recycling, the large molecular chains that make up plastics are broken down into simpler molecules that serve as raw materials for the chemical industry.
In the process, the plastic materials are degraded by heat or catalysts to the point where the macromolecules are broken down and only simple molecules, commonly called monomers, remain. From these monomers, other plastics or fuels could be obtained, depending on the technique used.
It is still an uncommon recycling process, but it has a promising future, as it is the only way to obtain basic monomers, being able to manufacture plastic of the same quality again.
Production of a new packaging or product
After going through one of the two processes above, either mechanical or chemical, the resulting plastic is fed into machines that produce plastic objects again.