Cartons also known as 'Tetra Packs' that contain products such as fruit juices, milk and soups are recycled by Sonoco Ltd, near Halifax, West Yorkshire. The value of cartons is in the aluminium lining and cardboard outer and the recycle process sets out to separate these layers. Dover District Council collects about 120 tonnes of cartons annually.
The bales are loaded onto the conveyor belt and dewired so that the cartons are fed loose up the conveyor to the pulper. This is done in 1.8 tonne batches
The cartons are then pulped using ambient temperature water in a pulper, using a large rotating screw. This separates out most of the polythene and aluminium layers from the paperboard layer. The paperboard is broken down into a fibre slurry, with the whole process taking around 20 minutes.
At this point the fibre slurry and the fine polymer and aluminium layers, used in beverage cartons to prevent leakage and provide a barrier to oxygen, are separated. The mix goes into a large conic drum, to be washed and to screen out heavy contaminants such as stones and glass. The moisture is then squeezed using a dewatering screw compactor.
The fibre slurry then moves on through a coarse screen. This is used to filter out the smaller pieces of polymer, usually from the outer layer of the carton, the fibre mix is then sent to the final screening process.
A specially-designed Kandant ScreenOne then removes any glue or final tiny pieces of polymer from the fibre slurry using an energy-efficient three-stage screening process in one machine.
The mixture then passes through the drum thickener. This reduces the water content to the optimum level for storage, with water content being reduced from 97.5% to 95% and the fibre content doubled to 5%.
Final Stock Chest
This has a capacity of 300m³, containing water and 15 tonnes of carton fibre and is the end of the line. Here the reprocessed fibre is stored in a large tank, ready for blending with fibre from Sonoco Alcore’s other on-site pulping operation to produce industrial-strength coreboard.
While this process is recycling the strong wood fibres contained in beverage cartons and putting them to good use, the facility is also a great opportunity for local authorities to reduce their carbon footprint, as the road and sea miles travelled by cartons for recycling will be reduced. Previously cartons collected through ACE UK bring banks were recycled at mills in Sweden. Recycling cartons at the UK facility instead will lead to an estimated annual reduction of 122 tonnes of transport-related CO2.
Also, if by using the new recycling facility local authorities and waste management companies are diverting beverage cartons from landfill, they will avoid landfill tax and gate fees. When the plant is running at its full capacity of 25,000 tonnes per annum, it could potentially reduce these costs by £3.6 m (based on 2013/14 costs).
By creating a domestic end destination for used beverage cartons, with a fixed price per tonne for cartons delivered, the facility also provides price stability for local authorities and waste management companies. It also enables local authorities with no-export policies for recyclates and an eye on the circular economy to have their cartons recycled in the UK.