Mechanical recycling

The first aim of VinylPlus is to stimulate mechanical recycling, taking into account the quality of the waste collected and the requirements of further processing methods and of the final products.

Novel or improved waste separation

These techniques separate a mixed or difficult waste stream into streams which can be handled by conventional mechanical recycling.

Neidhardt Recycling GmbH (DE): The input material is a PVC-aluminium composite used for blister packaging. The composite, which is supplied as a clean stream, is shredded down to 20 mm pieces. The shredded waste is transported by a conveyor belt to the acceleration rotor and ends up in the air stream between the rotor and the stator.

Aluminium and PVC are separated (delaminated) thanks to the high-rotation speed. The process transforms the aluminium sheet into balls, whereas the PVC sheet remains flat.

The delaminated mixture is then sieved on 4 successive sieves, yielding fractions with well-defined granulometry of <0.5mm, 0.5-0.7mm, 0.7-1.0mm. Aluminium and PVC are then separated by an electrostatic device. The PVC fraction is supplied to PVC converters manufacturing products such as pipes, separators, etc. The aluminium is also recycled into foundries or for special applications.

R-Inversatech: This Japanese technology separates fibres from PVC waste such as tarpaulins, using a high-speed beating technique. The fibres can be used in thermal and/or acoustic insulation. The PVC granulate is used in a broad range of flexible PVC applications.

Jutta Hoser: Jutta Hoser produces plastic mats for greenhouse flooring from recycled PVC composite films, plasticised films and coated fabrics. The mats have drainage holes allowing the plants to be watered from below. The remaining water is then drained away leaving a clean surface. The added heat insulation prevents plants from freezing in their containers. The flooring is suitable for driving on with small machines and it is easy to clean.

Caretta: Hemawe/Caretta has developed its own equipment and technique for separating fabric and tissue, etc. from soft PVC foils. Recyclable materials clad with fleece, fabric or textiles are poured into a shredder and chopped into sections approximately 4-6 cm long. The shredded pieces are then granulated and sieved to separate the fibres. The PVC is used to manufacture damp-proof courses, sound-absorbing foils and soundproof mats for pipe insulation.

Texyloop®: This processing module is an extension to the VinyLoop® plant. It treats coated fabrics with the aim of recycling both the PVC and the polyester fibres. The VinyLoop® process dissolves the PVC, allowing separation of the fibres which are recovered in the Texyloop® module. The PVC is further processed in the VinyLoop® plant. A 2,000-tonne/year module is installed in the VinyLoop® Ferrara plant in Italy.

Conventional mechanical recycling with special features

This includes mechanical recycling with some added features used in, for example, the production of large objects from mixed plastic waste. The mixed plastic waste is processed using conventional techniques (e.g. extrusion, moulding) into thick-walled objects such as shoe soles and urban furniture (e.g. park benches), traffic controllers and signallers, etc. Thick walls are required because the mix usually yields poor mechanical properties.

AgPR flooring recycling process: The AgPR cryogenic grinding recycling plant was built in 1993 and production started in 1994. Its production capacity is around 4,000 tonnes per year.

Rubber Research Elastomerics: In the USA, this firm uses a patented technology to mix PVC waste (tarpaulins and cable scrap) with shredded tyre scrap combined with a rubber compatibiliser. 50/50 blends produce harder products and could possibly be used to replace timber in certain construction applications.

Inclusion in other (non-plastic) materials

Light concrete: PVC waste is mixed into concrete to decrease its density. Such 'light concrete' is currently manufactured using polystyrene. Applications include non-structural elements like roofs, insulation walls and slabs covering gutters. Trials with PVC waste have been promising, although flexible waste failed to meet all the stringent migration tests. One advantage of this option is that it can be applied in several small plants.

Wood PVC composites: Plastic-wood composites are gaining a share of the decking market. Some firms are investigating new applications, for example, structural wood lumber and cladding. In the US some companies claims that their decking is manufactured from 95% recycled content, including reclaimed wood, sawdust and plastics. PVC has been tested along with other plastics such as PE and PP.

Non-conventional mechanical recycling

Compared to conventional mechanical recycling, non-conventional mechanical recycling methods are often more complex and have been developed to tackle PVC products that are more difficult to recycle. These materials are often composite materials or too contaminated to be accessible using conventional recycling. Examples of such waste streams include PVC cables where PVC could be contaminated with copper, or tarpaulins in which PVC is combined with polyester fibre.

Research in this area is very important for VinylPlus as it is a key element to meet the goal of recycling 100,000 tonnes of difficult-to-recycle PVC per year by 2020 .

The most promising technology in this area is undoubtedly VinyLoop®, which is a commercially developed process. Other technologies such as Poly-Tec, which consists in softening PVC before separating it, are at a relatively early stage of development. Such processes are still, in effect, 'mechanical recycling' because the PVC molecules are not broken down, but the PVC is separated by processes similar to those used in the chemical industry.

VinyLoop®: This is a patented process developed by the Solvay Group. PVC is separated from other materials through a dissolution process, followed by filtration and separation of contaminants. A solvent is used in a closed loop to dissolve PVC from the waste. This makes it possible to recycle PVC waste from composite materials and recover the solvent.