MELT FILTRATION | TECHNOLOGY


Candi Plastic deals with tricky contaminants


Gheorghe Campan (right), Managing Director of Candi Plastic Recycling, and his son Andreas, standing by the Ettlinger ERF 200 melt filter


For the past three years, Candi Plastic Recycling has been using an Ettlinger ERF 200 filter at its plant in Sollenau, Austria, where its performance was such that Candi chose a second melt filter of the same type for installation at SC Calex, its Romanian subsidiary. In Sollenau, Candi mainly processes cosmetics bottles and tubes with lid seals containing silicone as well as film scrap with a high aluminium fraction, such as that generated during the production of beverage packaging or yogurt pots. Candi’s Managing Director Gheo-


rghe Campan said the silicone contamination can cause specks in the


particularly good in dealing with contamination surges, since the filtration area is regenerated very effectively in a short amount of time,” he said. In the BKG HiCon V-Type 3G process, melt flow


from the extruder is split at the entry side and delievered to four screen cavities on two screen- bearing pistons with screens in each cavity. The piston removes one cavity at a time to expel contaminants by means of backflushing, while the other cavities continue filtration. This way, the melt throughput does not need to be interrupted. In addition to the two screen-bearing pistons,


there is a single hydraulically actuated displace- ment piston that operates during backflushing, said Nordson. When the differential pressure across the screen changer reaches a pre-set level because of contaminant build-up, the backflush sequence for all cavities starts automatically. For each cavity, the displacement piston retracts, creating a reservoir of filtered molten polymer. This material is then hydraulically compressed and discharged in reverse direction, back through the screen, carrying away contaminant for removal from the system. Christian Schroeder, Nordson’s global product manager for BKG melt delivery products, said: “In comparison with the earlier V-Type system, the height of the new HiCon V-Type 3G screen changer has been reduced by 30%, permitting a lower extrusion height. A single displacement piston is used for backflushing instead of having one for each screen cavity; and hydraulic piping has been optimised.” At K2016, Nordson launched another melt


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film product, leading to a deteriora- tion of the material properties, if the filtration efficiency is inadequate. “The ERF 200 fulfils our high requirements in every respect, even with this critical material,” he said.


Depending on the material, the


level of contamination and the screen size, Candi achieves throughputs of up to 700 kg/h with the ERF 200 model installed in Sollenau. The filter can remain in use for several weeks before it needs to be cleaned. It takes an hour or so to complete


the screen change and the recycling line needs to be only briefly inter- rupted, said Ettlinger.


filtration system, the BKG HiCon R-Type, which was developed specifically for recycling operations treating highly contaminated polyolefin or styrenic plastics. This has a different design in which melt flows through a fixed, cylindrical strainer tube with micro-conical holes that filter the contaminated melt. The contaminants are separated from the melt and then scraped by a rotating blade shaft from the surface of the strainer tube (see Plastics Recycling World, June 2017). Gneuss of Germany has installed an extruder and melt filtration system at another producer of strapping tapes, Consent Plastic, based in United Arab Emirates. Consent produces its own flakes out of collected PET bottles and uses these flakes to manufacture strapping tapes with a high tensile strength. Gneuss said that as part of an expansion,


Left: Nordson BKG HiCon V-Type 3G melt filtration system at Cyklop’s facility in Cologne, Germany


March/April 2018 | PLASTICS RECYCLING WORLD 21


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