A recycling arsenal

Nicola Brittain

A look at how one company’s recycling and compounding products look set to change the plastics landscape.

Recycling and compounding plastics is of increasing importance for many facilities in the process industry; and this was a consideration that helped drive technology giant Coperion’s acquisition of German manufacturing company and recycling specialist Herbold Meckesheim in 2022 - the companies have gone on to release an arsenal of high-end recycling products.

Herbold Mechesheim is now part of Coperion’s extensive recycling business unit and together they develop and produce machines and systems covering the entire production process: from shredding to washing and separating to drying of used, mixed and contaminated plastics such as plastic waste.

Since the merger, both companies have continued to develop and attune their technologies and report that their systems operate together with high efficiency.

PET recycling is a key area of focus

A key area of focus for the group is Polyethylene Terephthalate (PET) recycling, and it recently demonstrated a virtual PET recycling product at the ChinaPlas 2024 tradeshow in Shenzhen. PET is a thermoplastic widely used and recycled across the world; it is prized for its thermo-stability and can be recycled up to seven times before thermal degradation undermines its crystalline structure. This stability has made this type of plastic the most recycled in the world (92% of local councils in the UK are collecting PET for recycling).

The coming introduction of the ‘Plastics Tax’ in the UK will be applied to every product made from plastic that contains less than 30% of recycled polymer. There are many other similar taxes internationally, and these will be a huge incentive for plastic manufacturers to use more recycled plastics in their products.

The STS 75 Mc Plus extruder

A key plastic compounding technology from Coperion is the STS 75 Mc Plus twin screw extruder with its increased specific torque of 13.6 Nm/cm. This increased torque means the extruder can achieve up to 20% more throughput with markedly higher product quality meaning material costs per kilo drop and return on investment is reached more quickly. Coperion retained the proven Do:Di = 1.55 ratio of outer to inner screw diameter, thus ensuring secure scale-up to other STS model sizes.

The extruder is equipped with a high-power motor and a gearbox designed specifically for the high torque. Proven high-performance materials for the screw shafts ensure full torque transmission from the gearbox to the screw elements.

The higher fill level in the process section is crucial to the improved compound quality that the STS 75 Mc Plus achieves. It reduces shear stress and melt temperature and improves mixing behavior.

A gentle handling product

The result is extremely gentle product handling at high throughputs. since the process section of the STS 75 Mc Plus is equipped with heating cartridges that generate heat energy-efficiently where needed.

The K-Tron feeder offer maximum flexibility

Another essential Coperion solution on show at ChinaPlas was its K-Tron K2-ML-D5-T35 quick change feeder equipped with an ActiFlow smart bulk solid activator and EPC (Electronic Pressure Compensation). The T35/S60 feeder is designed for applications requiring quick changeover of materials and convenience of fast cleaning. The QC feeder allows for fast removal of the entire feeding module with screws in place for replacement with a second unit. Twin and single screw feeding modules are also available.

The ActiFlow smart bulk solid activator offers an innovative way of preventing bridging and rat-holing of cohesive bulk materials in stainless steel hoppers without internal hopper agitation. The smart flow aid applies gentle vibrations to the hopper wall, thereby activating the contained material with the optimal amplitude and frequency, automatically adjusted by the controller based on bulk material flow. The product has been designed to work with Coperion K-Tron’s line of gravimetric loss-in-weight feeders.

The 2400 Series vacuum receivers provide a high-capacity sequencing system primarily used where larger conveying rates or long distances are required, in applications with one or multiple destinations. They are designed to high quality standards for pneumatically conveying powder, pellets and granular materials for most industries. Conveying rates range from 327 to 6,804 kg/h (720 to 15,000 lb/h).

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