Sortability
To effectively design flexible packaging for a circular economy it’s important to understand what happens to it once it becomes waste.
Packaging waste sorting facilities, often called Materials Recovery Facilities (MRFs), use a series of steps to separate mixed recyclables into different material types. The sorting works by using differences in size, shape, and material properties of packaging waste items.
Most MRFs in Europe rely on automated processes, though many still have workers who manually sort certain packaging formats and materials, often to check quality. In some countries, sorting is still mainly done by hand.
The main sorting steps are usually similar, but each facility can have its own layout, equipment, and process flows. Many also use loop systems, where materials pass through sorting steps more than once for better results.
After the materials are separated, a baler compresses them into compact bales. This reduces the volume and makes transport cheaper. Each bale must meet a technical specification, which sets rules on purity, moisture content, bale density, contaminants, bale size, and bale wiring.
Components of the sorting process
Drum or trommel screen
A rotating cylinder that uses the size of the packaging to separate larger ‘oversized’ items from smaller ‘undersized’ particles. Smaller items and dirt will fall through the holes of the screen and typically this material will be classed as a residual fraction while larger items will continue through the subsequent processing steps.
Ballistic separation
Uses the shape and the ability of a packaging item to bounce to classify items as two-dimensional (2D) or three-dimensional (3D). The 2D fraction will consist of flat and thin materials such as flexible packaging, paper, and cardboard; these materials are thrown upwards towards the top of the machine.
Magnetic & eddy current separation
Used to separate ferrous and non-ferrous metals. Magnets are used to separate ferrous metals such as steel, whilst packaging containing aluminium foil can be separated by an eddy current separator, which uses a high-speed magnetic rotor to generate an electrical current. This produces a magnetic field which repels non-ferrous metals.
Optical sorting
Optical sorting systems such as Near Infra-Red (NIR) can be used to identify and separate specific polymer types and material combinations. The NIR sorter uses a camera calibrated to identify the individual polymer types.
Once the different fractions of material have been separated, a baler is used to compact the loose sorted material fractions, so the material is ready to be passed to a recycler.
Understand each of these processes and connect them to your packaging design choices by consulting the complete guidelines
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