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processing feature | Pellet screening

Virto’s ScreenX screening machines use MFVexcite

multi-frequen- cy vibration technology

Screen which has an integral gasket. This special construction creates precise and repeatable tensioning of the screen. The integral gasket is one moulded part, as is the one-piece centre disc with integral strain relief. This unitary construction integrates the screen gasket directly into the tension ring. It reduces cracks and crevices, making the screen easier to clean. ❙

The Virto Group includes the Italian screen manufacturer Cuccolini and markets its products in North America via its Virto/Elcan alliance. Its product range includes the patent-protected range of ScreenX circular and rectangu- lar screening machines which use the MFVexcite multi-fre- quency vibration technology to

deliver fine, efficient and high output separation. The group’s range of ‘standard’ circular vibration screening devices includes the VPB mobile units, VPM fixed-based multi- deck units, and VP2 low-profile

Sweco’s multi-tasking DC Classifier dries, cools and classifies plastics

Zeppelin’s RotoScreen

drum screener continuously removes

streamers from pellets

compact designs. Demonstration systems are available at

Cuccolini’s factory in Reggio Emilia, Italy, and at the

Virto/Elcan facility in Tuckahoe, NY, USA. The latter site also offers toll processing services. ❙

Witte of the USA initially developed its Witte 400 integrated, multi-step system for a major, global compounder and subsequently offered the design to the general market. It combines dewatering, drying, cooling, dedusting and screening into a single unit.

According to the company,

the system achieves product moisture levels as low as 0.04% in PA and 0.10% in PE, PS, PP, PVC, PET and other resins. It is also said to be


ideal for friable, glass-filled and micro pellets, accom- modating production rates up to 10,000 lb/h (4.5 tonnes/h). Installed downstream from underwater pelletizers,

the Witte 400 features a vibrating dewatering screen that removes surface water from the pellets and returns the water upstream for reuse. The mechanical dewatering minimizes the need for costly thermal drying, increasing overall drying capacity and delivering cost savings in machinery and energy consumption. In the fluid bed drying section, the system employ’s

Witte’s vertical air flow technology to dry the pellets at high air velocity which also removes light-density, off-spec material – the fines are captured in a dust collector. After cooling, the pellets are screened for oversized particles and for fines if required, although in many cases the latter is not needed. ❙

Zeppelin Systems of Germany has developed its RotoScreen drum screener for the continuous removal of streamers from pellets at throughputs as high as 120 tons/h. Automatic cleaning of the screener allows non-stop operation in three different modes – suction, pressure and circulation. The rotating drum screener is

gravimetrically fed with the plastic pellets. The mesh size allows pellets to pass through but retains the streamers which are transport- ed to a discharge by the drum’s

rotation and a directional gas flow. This gas flow is directed at the screen’s

surface and cleans its apertures during operation. ❙

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