Steinert crushes the black plastics problem

Germany – ‘Although the pure separation of black plastics is one of the main recycling tasks, most optical sorting machines are unable to handle it,’ Steinert Group observes. The specialist for magnet separation and sensor sorting has launched the UniSort BlackEye to tackle this particular problem.

A well-known issue is that the sensors of traditional optical sorting machines have been unable to distinguish the different types of black plastics from one another, because the soot used to blacken the plastic absorbs the visible and infrared wavelengths of electromagnetic radiation.

‘The UniSort BlackEye closes this gap and makes a pure separation of comminuted black components possible,’ says Hendrik Beel, Managing Director at the Steinert Group. ‘The investment pays off quickly because it enables operators to produce pure and thus more valuable granules.’

In fact, the company points out that recyclers producing mixed granules from purchased black polyethylene and polypropylene (PE/PP) currently pay a market price of about EUR 200 per tonne, depending on the material’s polyolefin (PO) content.

However, if they could concentrate the mixture into valuable fractions such as PE and PP they would be able to obtain a price of up to EUR 900 for the granules. The innovative Steinert system uses custom analysis software allowing it to recognise that each type of plastic has more or less its own ‘fingerprint’, says Beel. One of the reasons why this analysis is especially reliable is due to the fact that the camera doesn’t scan the conveyor belt pixel by pixel.

Instead, it simultaneously scans 320 pixels across the entire belt width, enabling even tiny variations in the near infrared (NIR) spectrum to be detected.

And Beel adds: ‘The UniSort BlackEye operates quickly enough to scan belts moving at up to four metres per second. During this time, it can scan about 35 million detection points or up to 5000 objects. This makes it ideal for efficient industrial applications for crushed plastic parts measuring between 10 and 30 millimetres.’

On average, the UniSort BlackEye has a throughput rate of one tonne of plastic flakes per hour.

Steinert’s new sorting system will be on display at next week’s IFAT trade show in Munich in Hall C2, at booth 451.