- Cost-effective technology to separate foreign bodies
- Working principle: different flying speed of the product and heavy materials
- First application: PET bottle recycling line
It is a common problem: every now and then there is breakdown caused by foreign bodies that enter the recycling machines with the feeding material. In simple cases there is “only” excessive wear at the grinding tools. Massive foreign bodies, however, can cause a breakdown of the machine. There are different approaches of how to solve this problem and how to avoid a breakdown. All of them have detrimental effects: inductive metal separators are only appropriate for detecting metals. But often foreign bodies are not metal parts but stones, shoes, wooden pieces.
For the separation of foreign bodies Herbold Meckesheim GmbH has developed a cost-effective, simple and efficient technology that is part of a pneumatic conveyor. Heavy materials are separated and evacuated from the product flow in an ascending pipe via a discharge chute. The underlying principle: the different flying speed of the product and heavy materials. All materials with a considerably different flying speed in the conveying pipe of the pneumatic system are separated. In addition, no further transport is necessary any longer.
A first plant has been sold for a PET bottle recycling line: entire bottles, not yet size-reduced, are separated from foreign bodies and at the same time conveyed to the next processing step. The customer was highly surprised to which extent foreign bodies were detected even during the first days of operation (see picture below). The line is suitable, for example, for the processing of bottles that have not yet been size-reduced, but also for separating foreign bodies from pre-shredded thick-walled parts. Not only metal parts but also mineral foreign bodies, generally all heavy parts are separated.
Process flow chart: Heavy materials are separated and evacuated from the product flow in an ascending pipe via a discharge chute (source: Herbold Meckesheim GmbH)