Mechanical recycling is using mechanical techniques to recycle packaging materials after use. To realise this, the packaging materials must usually first be collected and sorted. Recycling is any useful application with which waste materials are reprocessed into raw materials, materials and products with the same or a different purpose.
Considerations for mechanical recycling
- Mechanical recycling has been used for a long time for various materials, e.g. metals, glass and paper. These are not knowledge-intensive technologies.
- Using recycled material can lead to cost benefits.
- During mechanical recycling, the material may be contaminated because not all colourants and other additives can be removed from the recyclate. Colourants are hard or impossible to remove, as a result of which recycled materials become increasingly dark.
- Not all recycled materials are of food-grade quality. That is not a problem when recycling glass and metal, because those materials are heated to such an extent that the risk of contamination is eliminated entirely. However, it does pose a problem for the recycling of plastics and paper. As a result, only rPET may be used for food applications at the moment.
- You have to know what kind of material you want to recycle: you have to sort by material (glass, metal, wood, paper and cardboard, plastic) and sometimes by type (e.g. packaging glass, kraft (paper and cardboard) and PET (plastic)).
During a mechanical recycling process, the material to be recycled is usually cut or ground up first: into cullets (glass), flakes (plastic), fibres(paper and cardboard) or chips (wood). Next, any contaminants are eliminated with techniques such as washing and rubbing (plastic), sieving and de-inking (paper), leaving it for a while (glass) or incinerating it together with other materials (metal). The next step involves using the recycled material to make a new raw material.
After being collected, glass is first manually sorted at the glass recycling company and the largest contaminants are removed (mainly earthenware and plastic). Metal caps are removed using magnets. Next, any remaining contaminants, such as stone, porcelain, corks and labels, are removed with the help of machines. No water is used during this recycling process. Glass is heated up in a glass furnace to a temperature of circa 1,750o C, at which point it begins to melt. Once the molten glass reaches the end of the furnace, it is immediately formed into a new packaging. When this packaging has cooled, it is ready for use - usually at a different location.
Paper and Cardboard
Paper and cardboard are collected, cleaned, sorted and pressed into bales. These are then transported to the paper factory. The waste paper is then dissolved in water. During this process, the paper fibres are separated and paper pulp is formed. Contaminants in the waste paper, e.g. staples, paper clips, tape, pieces of plastic or even sand and polystyrene, are removed from the fibre mush using various sieving techniques. If it is necessary for the end product, the printing ink is removed as well. The fibre pulp can then be whitened with oxygen or bleached with hydrogen peroxide (H2O2) or ozone (O3). Once the pulp is ready for use, the paper production process can begin.
For the most part, metals such as steel and aluminium can be reused over and over again by being recycled. This results in the efficient and effective use of (new) raw materials. The biggest challenge with regard to closing the packaging chain for metal materials is making sure they end up in the correct waste stream and are not disposed of as litter. After recycling, metal packaging materials can be reused to produce new packaging materials or for other purposes. Recycled metal can be used for all kinds of metal products, this especially the case for steel. For aluminium, the application possibilities depend on the material's alloy.
Plastics must first be carefully sorted and cleaned. The cleaner and purer the waste stream is, the higher the quality of the recycling process will be. The sorted plastic streams are pressed into bales and transported to the recycler. There, the material is often sorted again, ground up and washed before being melted down in an extruder, after which it is turned into new plastic granulate (pellets). Extra colourants and additives can be added to the recyclate to improve its properties. This granulate material can then be processed into new packaging materials using various techniques, including extrusion, blowing, injection moulding, etcetera.
Wooden packaging materials are sorted into different classes and then shredded into tiny pieces (chips). After adding glue, these chips are pressed into new shapes, such as pallet blocks or chipboard products.
Situation in various countries
The waste stage
The use of packaging materials is subject of European legislation. On 20 December 1994, the European Parliament and the Council of the European Union introduced the Directive 94/62/EG (hereinafter: Directive) for packaging materials and packaging waste. This Directive was subsequently revised on 22 May 2018. The goal of this Directive is to limit the use of packaging materials and stimulate recycling, reuse and other useful applications for packaging waste.
All EU Member States are required to implement the Directive in their own national legislation. Every Member State has its own way of doing so. Packforward started to give an overview of the way the different Member States implemented the Directive, but the overview is not completed yet. You can find more information for the Netherlands, information about other countries will follow soon.
Despite the efforts made with regard to collecting, sorting and recycling packaging waste, new raw materials will have to flow into the packaging chain in order to safeguard the quality of the material and compensate for the loss of material in the chain. For a growing number of the new raw materials, steps are being taken towards a circular economy, e.g. by making use of biobased materials.