MACHINERY | MIXERS
Additive
Buffer Hopper
MIX-A-LOT MXL
Additive
Buffer Hopper
LIW
LIW
Polymer 3
Polymer 2 Polymer 1
Extruder
Polymer 3
Polymer 2 Polymer 1
Extruder
Figure 2: Schematic’s showing how the incorporation of Coperion’s latest MIX-A-LOT system (right) can simplify compounding plant configuration
the MIX-A-LOT unit provides easy access to the process chamber, while an additional opening at the discharge flap facilitates inspection and cleaning. MIX-A-LOT units are available in three sizes, the
Right: The MIX-A-LOT system from Coperion features a large front opening to provide access to the process chamber
largest of which is rated at a capacity of up to 5 tonnes/h. An ATEX version is also available and the surface of the chamber can be electro-polished. Experimental trials run in Coperion’s testing center have shown good mixing quality, reports the company. Realising maximum productivity in PVC dry blending applications – and improving the final quality of the blend – requires the ability to rapidly cool the PVC blend at the end of the heating mixing stage, according to Plasmec, which claims to have developed the first horizontal cooler mixers more than thirty years ago. Its latest models use a new high efficiency cooler with an optimised water circuit that the company says applies thermo-fluid dynamic engineering to provide a significant increase in performance. The new cooling interspace is designed to withstand a working pressure up to 2.5bar, the typical operational pressure of factory closed circuit chillers. The company says this considerably improves productivity, allowing the equipment to cool more than eight batches of U-PVC dryblend from 120°C to 40°C every hour.
Compounding mixers Compounding mixers come in both batch and continuous variants, both of which offer their own distinct advantages. Batch mixers (such as Banbury types) can handle difficult to feed and poor flowing materials
22 COMPOUNDING WORLD | November 2017
Source: Coperion
very well. “With increasingly efficient temperature control, there is a possibility for much increased residence times, which can in theory be infinite in a batch mixer, thus allowing increased mixing cycles or holding for reactive compounding,” says Farrel Pomini’s Lloyd. Continuous mixers, meanwhile, offer lower capital costs and reduced space requirements, as well as generally needing fewer operators. They also provide flexibility; independent processing variables allow the mixer to efficiently be adapted to formulation changes. The Farrel Pomini Continu- ous Mixer offers a short length/diameter ratio that “ensures that shear sensitive carriers can be processed and loaded whilst ensuring there is no thermal degradation of the base polymer,” says Lloyd. In addition, the stability of a continuous mixer can allow high consistency and increased control. The latest developments for the Farrel Pomini
Continuous Mixer, such as the patented Self Aligning Seal (SAS), the Automatic Vent Plunger and the Adjustable Dam Assembly, are available as upgrades and are aimed at increased operational efficiency or machine flexibility, Lloyd says. The company has also evaluated other applications to see which might benefit from the mixer’s capabilities. “It is excellent at producing very highly filled and temperature sensitive materials due to its large free volumes and efficient mixing action,” the company says, citing example applications such as flame-retardant compounding and PET processing. While continuous mixers
offer low running costs and good flexibility, both can be enhanced by good operating practices. Keeping the equip-
www.compoundingworld.com
Pneumatic conveying
Pneumatic conveying
PHOTO: COPERION
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