machinery | Mixers Right: A
complete MTI mixing system for PE-Xa at pipe maker
Agru-Frank in Germany
the friction created also causes the material temperature to increase quite rapidly. Uni Tec models are low speed mixers, which have just one mixing tool rotating with a tip speed of around 0.8 m/s. This type of mixer is used for materials that require gentle handling or that must not be exposed to a significant increase in temperature during mixing. In cases where dispersion by the one mixing tool is insufficient, one or more high speed choppers can be installed to improve mixing quality. At Mixaco, sales manager Andreas Backhaus emphasises developments in container mixers for compounds and masterbatches. He says the company continues to improve its Multi Tool mixing technology, which was first introduced in 2009, with the addition of extra features. He too highlights conformity to increas- ingly tough ATEX requirements.
individual dosing/mixing system on each production line,” he says. A single MTI mixing system can serve multiple
extrusion lines while the spatial separation of the two stages helps pipe makers meet safety requirements applying to the processing and storage of peroxide and other additives, which carry an explosion risk. Organic peroxide is both flammable and toxic (although the hazard is reduced with peroxide/white oil solutions), while PE and additives in powder form are typically classified as combustible substances or substances carrying a powder explosion hazard.
Right: MTI’s Uni Tec batch mixer features low speed mixing for thermally sensitive blends
Explosive markets Kaiser says MTI mixers are ATEX (explosive atmosphere)- compliant. “We continuously adapt to changing stand- ards,” says. “The mixing technology continuously improves, especially the development of mixing tools to improve the mixing performance for individual materials and mixing processes and of course wear protection.” MTI offers universal Uni Tec and horizontal Flex-Line
mixers for this and other applications. Both use short mixing cycles that put minimal strain on the raw materials, but still provide a high quality mix. They operate under ambient conditions or with pre-defined temperature profiles. MTI has been selling both types of mixers since the mid-70s, but Kaiser says they have evolved in terms of energy consumption, flexibility and control systems. Flex units are high speed mixers (turbo mixers) that
have multiple mixing tools rotating at high speed (tip speeds are around 30 m/s). Through intense material movement, the dispersion of ingredients is very good but
54 COMPOUNDING WORLD | November 2015
www.compoundingworld.com
Versatile mixing options Backhaus calls the company’s CM MT container mixer series a “Jack-of-all-trades,” with its suitability for use in all areas where high-quality materials are used. Models are available in sizes from 6 to 2,000 litres. “With its numerous individual tool possibilities, any desired mixing result can be dependably obtained,” Backhaus claims. He also cites high dispersion and homogeneity without the transfer of excess mechanical energy into heat in the product, making the MT very well suited for processing heat-sensitive materials. “The temperature increase in the MT container mixer is up to ten times less than in a conventional mixer– typically between 0.5 and 1°C per minute,” he says. The mixer can be configured for various ATEX
conditions, including ATEX 20/22. For this application, Mixaco uses a newly developed technology (certified by German TÜV), which operates without the need for a nitrogen atmosphere. Backhaus also highlights Mixaco’s “tool-free” Revo- lution mixer for homogenising granulates gently with
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