Approximately 25 years ago, Herbold Meckesheim (Meckesheim, Germany) commercialized the wet granulation technique, thereby setting a new standard in the postconsumer recycling industry. The new technology offered immediate benefits: There was less wear and tear; the optimum cooling during the size reduction process eliminated plasticization issues; and effective separation was achieved from the first processing step. Since then, Herbold has steadily refined and improved the technology; the latest developments are on display this week at Plast 2015 in Milan.
At the booth, the Herbold wet shredder HGM takes pride of place. Unlike most shredders, water is added right at the beginning—at the pre-size reduction step—rather than only during the next step, i.e. the granulation process, where further size reduction occurs.
Wet shredding and granulation technology is extremely well suited for highly contaminated material, such as agricultural film and postconsumer film from households. Wet granulation has proven to significantly increase the service life of the knife blades, thus lowering operating costs. Also, wood and paper fractions mixed in with the film are more easily detached earlier on during the wet shredding process.
In addition, Herbold supplies a range of granulator housings with interchangeable wear plates, which considerably increases efficiency and shortens downtime, as the wear plates can be easily replaced, instead of having to rebuild the housing. The wear plates can also be exchanged for rotors; conveniently, the blade carriers can be unscrewed, eliminating the need to disassemble, rebuild and balance the rotor when replacements are required.
Further at the booth: The Herbold plastcompactor, that, when installed at the end of a wash line, serves to turn film, fibers and foams with low bulk densities into an agglomerate with high bulk density and excellent flow properties. It also acts as a very efficient drying step. The resultant material is used to homogenize large loads of 20 tons, in order to produce the required product properties. The Herbold plastcompactor can handle capacities of up to 1,500 kg/hr.
The company has also built a new technical center in Meckesheim near Heidelberg, where industrial-scale tests can be performed using test material supplied by customers. The tests run through the complete operation, as this occurs in a washing and agglomeration plant, producing ample quantities of sample material for the customer and considerably facilitating investment decisions.