A virtuous cycle

The circular economy is aimed at reducing consumption of resources and regarded as a key factor in climate protection. In the last few years, Kubota Brabender Technologie has demonstrated how new processes and products can have their origins in innovative ideas. Bernhard Hüppmeier, Head of Business Development at Kubota Brabender Technologie, confirms: “In the last few years demand for feeding solutions, aimed at recycling synthetic fibers, has increased steadily.” Equipment for feeding components derived from used tires and woven fabrics as well as from familiar PET bottles is in demand. Some materials like rubber pellets are already processed to the extent that they can be fed using a normal feeder. In contrast, others require a feeding concept specially matched to their material properties.

Used tires are reduced to palm-sized pieces in shredders and then ground down to small pellets in pellet plants. All residual metal is then removed, leaving pure rubber crumb for reuse. But used tires also contain woven fibers like polyester and polyamide fibers, which can be vacuumed off during the shredding or grinding phases. In extrusion processes these fibers then serve as reinforcement or bulking agents for new polymer blends and can be processed into fiber-reinforced polymer compounds by mixing in additives.

Beverage cartons also consist of valuable raw materials: a combination of cardboard, plastic and often aluminum. However, the cellulose fibers reclaimed during recycling have a significantly longer fiber length and better strength properties than most other types of waste paper. They are therefore particularly suitable for producing sturdy corrugated cardboard packaging. In the so-called Palurec method, the remaining PE/aluminum foil remnants and closures are separated using a zigzag sifter. This is necessary, because they feature very uneven ‘particle’ sizes, have poor pourability properties and tend towards severe bridging. A special feeding solution provided by Kubota Brabender Technologie is therefore used when LDPE (low density polyethylene) is being processed – the FiberXpert. This fiber feeder is particularly good at handling fibers of different lengths, which snag easily. For pelletizing purposes, the FiberXpert feeds the reclaimed LDPE into a twin-screw extruder. This enables it to be reused for various applications.

In the European Union, an estimated 1.6 million metric tons of carpet are disposed of annually. According to a very recent study by market research institute Goldstein Market Intelligence, around 95 percent of this quantity ends up at disposal sites or incinerator plants. A sensible alternative to incineration is recycling waste carpets made of high-grade synthetic fibers like polyamide (PA) or polypropylene (PP). There are two solutions for waste carpets or carpet remnants made of PA, which consist of the texturized carpet continuous filament yarn BCF (bulk continuous filament). They can be chemically recycled into polyamide or mechanically processed into secondary plastics. To this end, PA carpets are sorted according to their fiber components PA6 or PA 6.6 and then shredded. After separation, they are fed via silos into a depolymerization process.