STEINERT UniSort BlackEye for the separation of black plastics

The STEINERT Group has launched the UniSort BlackEye — an optical sorting system that enables recycling companies to produce high-purity granules from black plastics.

At the heart of the sorting system is the detection unit, which is located above the conveyor belt and equipped with hyperspectral imaging (HSI) technology. A source of light illuminates the plastic flakes on the conveyor belt while a camera system analyses the reflected light. Using stored reference spectra, the company’s analysis software recognises whether an item is made of plastic, wood, glass or paper and whether it is a dark object. The camera simultaneously scans 320 pixels across the entire belt width, enabling even tiny variations in the NIR spectrum to be detected.

In cases where the operator wants to separate polyolefins such as polyethylene (PE) and polypropylene (PP) from one another, or sort other types of plastic out of a mixture of materials, the software transmits the corresponding position data to the compressed air system installed at the end of the conveyor belt. Within a fraction of a second, it opens the appropriate high-speed valve so that a well-aimed blast of compressed air causes the targeted material to be ejected.

The unit operates quickly enough to scan belts moving at up to 4 m/s. During this time, it can scan about 35 million detection points or up to 5000 objects. This makes it suitable for efficient industrial applications for crushed plastic parts measuring between 10 and 30 mm. On average, the product has a throughput rate of 1 tonne of plastic flakes per hour.