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processing feature | Pellet screening

The new Vibroscreen high-capacity two- deck classifier measures 100 in

(2.54 m) in diameter

and can separate up to 70 tons/h of bulk solids into three fractions. For example, it can be used to remove

over-sized longs and angel hair as well as

under-sized fines and dust from plastic

Gough pro- duced this direct-drive low-lying separator for a Malaysian masterbatch maker

pellets. The gravity-fed unit, which is also offered in diameters down to 18 in (460 mm), can operate on a batch or continuous basis. Also new from Kason is the Flo-Thru low-profile

Vibroscreen screener. This also uses two screening decks to separate bulk material into three fractions. However, it features two unbalanced-weight gyratory motors mounted on opposing exterior sidewalls of the unit, instead of one motor positioned beneath the screening chamber, significantly reducing height requirements. In addition , the design allows vertical alignment of

the top inlet and bottom outlet, permitting the smallest fraction to descend through the screener in a straight- through path at high rates; the larger fractions are ejected through spouts at the peripheries of the coarse-mesh upper screen and fine-mesh bottom screen. The Flo-Thru design is offered in diameters from 18 to 84 in (460 to 2,135 mm). Both the high-throughput and low-profile Vibro-

Kubota’s Super Platon system can identify pellets with black spots as small as 0.1 mm

screen models feature quick-disconnect clamps between each screen frame. These provide rapid access to the inside of the machine for inspection, screen changes and cleaning. In addition, an optional air-lift device can be installed to pneumatically raise any of the screen frames, allowing one operator to carry out tasks that would previously have required two people.

Kason also offers its Vibro-

screen units in combination with circular fluid-bed dryers to provide an integrated system for both screening and then drying/ de-watering the correctly-sized pellets. A 30 in (762 mm) diameter screen is combined with a 40 in (1,016 mm) dryer that can remove


up to 50 gallons (1,900 litres) of water per minute and can dry up to 700 lbs (320 kg) of material per hour. ❙

Kubota of Japan launched its latest Super Platon pellet screening system at the end of last year. It is said to be able to identify and remove pellets with black spots as small as 0.1 mm as well as other off-colour contami- nants, such as charred, discoloured or brown-striped pellets. Detection is achieved using four high-resolution

cameras and a new light source that features LED lamps in a dome arrangement. According to Kubota, this allows transparent materials to be screened using the device. The Super Platon can used to check a stream of

pellets either on-line after the pelletizer and size screener, or off-line. An air nozzle is used to remove defective pellets. ❙

Midwestern Industries of the USA offers several ranges of vibratory separators, including the ME and MR Gyra-Vib series machine, plus a Low-Profile design. The ME machines are designed for applications that

require a wide range of vertical and horizontal move- ment intensities. They feature a variable-speed pulley and a motor mounted on an adjustable slide base for precise control of the frequency. The MR model uses a conventional design with a centre-mounted motor and a special weight system to control the vibratory motion during the screening process. The Low-Profile model has two vibratory motors positioned 180o

apart on external adjustable mounts to

maximize space and screening efficiency. ❙

Rotex of the US developed its Plastic Pellet Screener specifically for compounders. It is designed to provide efficient removal of off-size pellets and longs, as well as delivering quick changeovers between batches. Designed primarily for batch

operations, the screener uses a special horizontal gyratory-recipro- cating motion with a positive displace- ment stroke to remove off-size material without losing good, on-spec pellets. The motion spreads pellets across the full width of the deck with no vertical action or hop. Faulty

pellets remain flat rather than upending,

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