Mechanical Recycling Options
Mechanical recycling refers to operations that aim to recover plastics waste via mechanical processes (i.e. grinding, washing, separating, drying, re-granulating and compounding). In mechanical recycling polymers stay intact, this permits for multiple re-use of polymers in the same or similar product–effectively creating a closed loop.
Although the technical capability exists (in limited quantity), the challenge with existing processes for mechanical recycling of multi-material flexible packaging is the need to know what the incoming resin composition is and keeping it consistent and relatively clean. This makes it highly challenging to use multi-material flexible packaging collected at the curbside where much of this information is unknown and unpredictable.
Yet, as we saw with the “collaborative projects”, as more information and processes are tested for effective collection and sortation, wider application of these technologies may emerge.
Based in Trenton, NJ, TerraCycle is best known for upcycling of consumer goods into new products. Lesser known is that TerraCycle has a significant in-house ‘plastics to pellets’ team. Using melt-flow technology and compatibilizers, the company can take known multi-material flexible packaging and create new resins for use with other in-house products. Because this process requires an understanding of the resins used within structures, Terracycle limits feedstock to material directly received from manufacturer’s (pre-consumer), or collected through targeted campaigns with select post consumers – their ‘brigade program’. Brigade participants register to collect specific materials and brands only, in return they receive a minimal payment and free shipping for their efforts.
- Reuse into resins permits for greater application into alternative products (i.e. manufactured wood)
- Extensive sortation is needed. For food contact structures, cleaning would be required. This makes collection at the curbside currently impossible.
Website: Terracycle Plastics to Pellets
The British firm Enval, offers proven technology to recycle aluminum based plastic laminations. Using a microwave pyrolysis technology, the company can separate plastics from aluminum and process both into new end products. Plastics become synthetic gases and oils and the aluminum can be collected and sold.
- Trials suggest contamination of food or beauty products is not an issue in the value of the final end product
- Limitation of aluminum-based laminates limits volume opportunities
- Odor with storing materials to accumulate larger volumes is a concerns for both consumers and processors
Based in Bielfeld, Germany, Saperatec promotes a micro-emulsion technology that can separate the layers inherent to a multi-layered structure in order to recover each of the individual components. This is a five step process:
1. Crushing: done in order to create as much contact surface as possible for micro-emulsion.
2. Micro-emulsion: highly specialized surfactant is applied in order to reduce the surface tension between layers. After mixing at low temperatures individual layers will sort.
3. Washing: After layers separate they are washed and conditioned.
4. Sorting: Materials are captured by resin type.
5. Drying: materials are dried for resale.
- The only currently available technology which can separate plastic layers to create more defined resins.
- Higher water and energy demand than alternatives as a result of washing and drying requirements.
- Still requires an understanding of structure composition prior to beginning process. This makes it unfeasible for curbside collection programs and limits processing to one structure format at a time.
Newcomers from Allentown, PA, Zzyzx Polymers is using continuous mechano-chemical compatibilization (CMC) to create new plastics. CMC differs from traditional compatibilization as it does not rely on melting. CMC cools plastics to maintain a solid state and then subjects them to shear force. This force breaks polymers apart. Polymers are then chemically recombined, allowing compositions to bind with other polymers or fillers.
- This process does not require high sortation or cleaning which reduces time, costs and efforts.
- The application of this technology to multi-material flexible packaging still requires an understanding of the resins within the structure. This makes collection at the curbside currently impossible.
Website: Zzyzx Polymers