Profiles of mixed plastics

PROMECO has developed several systems to recycle commingled mixed plastics fractions, usually collected from the MSW.

The recycling industry has long since found appropriate solutions to recycle, reuse and exploit the value of some recyclable polymers, in particular PET and HDPE bottles and containers or polyolefin films.
These materials have long been collected separately, or mechanically selected from a more or less differentiated waste stream.

However, downstream of a traditional mechanical selection systems remains a fraction consisting primarily of light materials. Typically, its composition is characterized by:

• High presents polyethylene (PE, 40-60%)
• Presence of polypropylene (PP, 3-10%)
• Residual presence of other polymers (PS, EPS, PVC, PET, etc.)
• Paper and cardboard, textiles and aggregates 40-50% of total

This mixture has interesting enough properties, which can be modified through:

• enrichment (addition in mixture of virgin polymer: HDPE or PVC to improve stiffness, HDPE to improve the smoothness of extruded)
• addition of fillers or fibers (fiberglass) to improve the mechanical strength

The product obtained recycling mixed plastics containing mainly polyolefins has features that make it suitable for use in place of wood. When the original properties of the product obtained are lower than those of wood, suitable addition of other polymers, fillers or fibers can significantly improve them. On the other hand, plastics are completely insensitive with respect to moisture, fungi or bacteria, and immune to problems caused by the absorption of water and freezing during the winter months.

The structure of the plant

The basic module: pretreatment and production of simple profiles

The plant consists of two modules.
The first module focuses on the system PES-Promeco Extruder System, allowing the pre-treatment of the input material.
This is received in bales or in bulk. A loading system allows to feed, through a a conveyor belt, a screen star. The main purpose of screening is to sort out aggregates of small size and to prepare the material for the next phase of automatic or manual selection.The selection allows you recover recyclable fractions and intercept foreign bodies of significant size, if any.
Then the material is processed by a PROMECO KR series shredder, to obtain a homogeneous product size and facilitate the next stage of densification.
If necessary, a magnetic separator for the removal of ferrous and an eddy current separator for non-ferrous metals are installed over  the belts carrying the shredded material to the PES.
The Promeco Extruder System is equipped with a hopper that feeds the material to the machine and a vibrating table to optimize the dosage of the flow in the extrusion chamber, where the actual process of aggregation/densification takes place. The material is subjected to high friction and pressure, generated by the rotating screws of the extruder, and is then pushed through an extrusion matrix that determines the shape and size of the final product.
During the process heat and steam are generated. The latter, along with possible dust, is collected by an exhausted air suction system and, if needed, sent to an air treatment system. The hoods sucking the air to treat are located above the extruder feeding system and over  the stabilization track. From the matrix, the profile is pushed along a stabilization track to a cutting or size reduction system that regulates the product according to the desired length specifications.
Eventually the product may move into a forced ventilation cooling system, where it will stay for a determined time before being stored in a specific area.

The product moves then  into a cooling system in which forced convection persists for a determined time, and is eventually stored in a specific area.

When the profiles are completely cooled, they are collected and further processed (eg. Shaper machine equipped with cutting tools to shape the profiles according to the type of product requested or placed in a conformation).
The scraps and dust produced in this phase can be collected and reused in the process.

Advantages of the system PROMECO

• Ease of maintenance
• High production capacity: 1500-200 kg/h
• Versatility
• Low investment costs
• Minimum floor requirements
• Material with high density (adjustable value)
• Product size and shape suitable for the intended use
• Low operation and maintenance costs compared to traditional methods

Additional modules

The add-on modules allow you to apply the technology traditionally used in the plastics industry for a variety of products.

In particular, mixtures of materials recycled mixed plastics have been used successfully for food:

• Lines of compression molding (compression molding)
• Extruders lines combined with compression molding / injection or intrusion (Flow Moulding)
• Extruding hollow sections
• Coextrusion lines, in which surface layers of virgin polymer covering internal structures din recycled material