Front Cover Feature Know-how from AZO – individual solutions The task facing AZO in recycling processes of this kind is generally the planning and design of the layout for a fully automatic feeding system for an extruder and the implementation and installation of the plant. The plant concept not only needs to be cost-effective but also compact, without losing flexibility. The first stage involves testing the feedstock, for example shredded film, flakes, granulate, shedding, dust etc., for their product properties in AZO’s own in-house laboratory and test centre. The results provide detailed information that allow us to deduce characteristics such as bulk density, particle shape and size, moisture or flow properties. The findings can then be used in planning the plant and layout. Post-consumer raw materials, such as crushed packaging film from confectionery, crisps etc., at times demonstrate very low bulk density of less than 0.1 kg/l. This is why AZO relies on a purposedeveloped receiver with a large-diameter outlet and valve technology with no obstructive contours in the product flow at the outlet. If necessary, further agitator technology and discharge aids can be used. The feedstock is first discharged from the containers and fed into the production line. Flexible pneumatic conveying systems charge the production line and ensure that raw materials are available for production, even when the properties of the raw materials change.
In order to satisfy even the most stringent of customer quality standards, AZO has developed more advanced solutions: • A loss-in-weight feeder ensures the highest degree of accuracy in dosing. • Receivers, which have been purpose-designed for recycling processes, guarantee discharge behaviour even for extremely lightweight ground film. • Protection of plant components against wear and use of special pump technology for handling abrasive materials • Magnets and metal separators remove any last traces of metallic contaminants, thus improving product quality and protecting the technical plant from damage. • Low-impact vacuum conveying systems for the finished product help to prevent generation of dust or angel hair. • Efficient degasification via extruders or downstream thermal drier remove gaseous contaminants and unpleasant odours from the end product. If a number of other admixtures need to be used, it is advisable to integrate the AZO®MIXOMAT into the plant. The different components are sucked in here in accordance with the formulation, then weighed precisely and blended into a homogeneous mixture. This means many raw materials can be conveyed to a single gravimetric dosing unit and then into the extruder, thus saving costs. Only then is homogeneous blending guaranteed in the extrusion process and thus provides the basis for end products with consistent and high quality, ensuring stable running of processes. It is therefore essential, throughout the planning process, to be able to respond flexibly to individual customer requirements and take into account findings about the properties of the raw materials. Exacting standards are also set for high plant availability and AZO has developed and established appropriate technologies to satisfy them. Only a design that makes cleaning easy and carefully considered planning allow fast changeovers of products and shorter downtimes, OCTOBER 2019
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