Plastic : Precise sorting with the AirLift from Westeria

Applications include, for example, the recycling of PET bottles, where the valuable PET fraction can be cleaned with high efficiency and purity from light impurities such as labels made of PE film or paper. Conventional over-belt extractors or even air classifiers used in composting plants, for example, are very suitable for separating fractions of different weights in waste streams. However, according to Westeria, they "fail" when it comes to distinguishing such pre-sorted or inherently similar lightweight components. This is where the AirLift concept comes in, according to the company, which can also be integrated into existing plants as a replacement for conventional air classifiers, where it is then able to separate plastic film from paper, for example, or different plastics from each other.

The entire AirLift system consists of three components. The high-speed conveyor belt (SpeedCon type), designed for particularly long belt life, feeds the material at up to four meters per second, the central element, to the AirLift, which is finally followed by the AirWheel. The possible working width of the AirLift is between 1,000 and 3,500 millimeters, depending on the version. In the widest configuration and with a particle size of 60 to 250 millimeters, up to 320 cubic meters per hour can be fed through. The maximum haul-off capacity is 5.6 tons per hour. In order to achieve a high level of operational reliability, automatic gate controls during operation prevent blockages on the infeed and discharge side. This automatic gate regulation also ensures exact adjustment of the throughput height to the individual separation target thanks to its infinitely variable adjustability.

Directly below the detection point, the SpeedCon bends by 20 degrees. This makes it easier for the air stream to get under the light parts. This "trick with the kink" gives all the components of the input stream to be sorted a ballistic trajectory, the shape of which (the throw) can be regulated via the belt speed by means of the integrated control system and thus adapted precisely to the task in hand. The diametrical downdraft principle enables particularly high selectivity. Depending on the input material, purity levels of over 95 percent can be achieved. For example, evaluations of an AirLift system installed at a working width of 2,800 millimeters in the feed of mixing plastics to an NIR, that more than 90 percent of the desired film fraction could be reliably separated. In this way, the system enables a significant reduction in disposal costs or an increase in cost efficiency in recycling operations. By removing the mixed plastics from the films, which are usually on top, the NIR sorting process is relieved and delivers a significantly better sorting result. The entire, three-part AirLift system can be used as a subcomponent of a more extensive sorting system and is designed in such a way that it can be retrofitted without any problems.