What are your thoughts on recycling plastic? Discussions about its value have been all over the map in recent years. Mechanical recycling is the most common process for turning plastic waste into reasonable materials, and it certainly has its pros and cons. Needless to say that some people think it’s a waste of time while others believe in it religiously. So what is the truth?
First of all, mechanical recycling is just one option for recovering valuable materials from plastic waste. Chemical recycling is another option. The big difference between the two is actual practice. Mechanical recycling is a proven business that has thrived for decades. Chemical recycling, although doable, is utilized on a much smaller scale. It is costly, polluting, and even a bit dangerous.
Mechanical Recycling’s Basic Premise
Mechanical plastic recycling rests in a basic premise: scrap plastic can be melted down to make new products. The premise is essentially true, though there are some caveats. The first caveat is that mechanical recycling reduces the integrity of the material itself. As a result, manufacturers are reluctant to use 100% recycled plastic for many of their applications. They mix it with virgin plastic instead.
The second caveat is that mechanical recycling only works when recycled materials are separated and cleaned. You cannot mix two different types of plastic in the same process. You also need to make sure that the plastic waste is clean before processing so that the resulting material is not contaminated after the fact.
Sorting, Cleaning, and Collecting
Mechanical recycling begins with sorting. In an industrial setting, companies sort their plastics in advance of sending them to a recycler. When a recycler like Tennessee-based Seraphim Plastics picks up a load of plastic purge and cutoffs for example, there is nothing else in the load. Seraphim Plastics employees do not have to sort through the plastic waste prior to processing.
Sorted plastics also need to be cleaned and decontaminated prior to being picked up. That is something else Seraphim Plastics’ customers do before the collection truck arrives. This is what makes industrial plastic recycling so much different from its municipal counterpart.
Municipal plastic recycling programs merely ask consumers to place all their plastic, glass, and paper products in a single bin. The first round of sorting takes place as the materials are loaded into trucks. But at the recycling center, additional sorting needs to be done. Different types of plastics must be sorted from one another and any trash mixed in. Then the plastics need to be cleaned.
Plastic Grinding and Shredding
The final step in the mechanical recycling process is reducing the plastic waste to tiny pellets or flakes. This is done with grinders and shredders. At Seraphim Plastics, they use a series of grinders to turn plastic waste into small pellets called regrind. The regrind is added virgin plastic to make new products.
Some commercial recyclers use shredders to reduce plastics like PET to fine flakes. The flakes have tons of applications. They can be used to make new PET bottles or turned into small fibers that are spun together to create plastic threads. Those threads then go on to become carpet fibers, fabrics, etc.
The most interesting thing about all of this is that industrial plastic recycling works because it is simple and cost-effective. Municipal recycling doesn’t because it’s labor-intensive and costly. Both types of programs are rooted in mechanical recycling. So why does one work and the other doesn’t? The answer lies at the source of the plastic waste. From the source flows the entire mechanical recycling process.