Fraunhofer develops black plastic sorting technology

The Fraunhofer Gesellschaft (FHG), a research organization based in Munich with institutes spread throughout Germany, has announced a new method for sorting black plastics by type has been developed by the Institute for High Frequency Physics and Radar Techniques (FHR), Wachtberg; the Institute for Optronics, System Technologies and Image Exploitation (IOSB), Karlsruhe; and the Institute for Intelligent Analysis and Information Systems (IAIS), Sankt Augustin.

“For the first time, we have developed an affordable sorting system that detects every plastic color, including black, both in real time and in large quantities,” said Professor Thomas Langle, department head at IOSB, in an interview with Phys.org. “We call this system blackValue.”

The system relies on a radar camera at its core, which emits terahertz radiation against shredded plastic scrap. This, along with a color camera to determine shape and additional properties of the plastic, allows the system to analyze individual particles to determine plastics type. It can then choose which individual pieces to knock out of the stream using precisely aimed blasts of air. 

This blackValue system has a 98 to 99 percent success rate, according to FHG.

“The higher the frequency used by the camera, the more precise the measurements,” Dirk Nüßler, business unit spokesman for production at FHR, told Phys.org. “But greater precision comes at a higher price.”

To promote affordability, Nüßler said the blackValue system uses certain algorithms developed by IAIS, to detect the slightest difference in the radiation spectra while allowing the conveyor belt that initially carries the plastic scrap to travel at the optimal speed. 

Researchers will present a transportable belt sorter with the camera at the World Conference for Non-Destructive Testing (WCNDT) in Munich, June 3-17, 2016, Phys.org reports. FHG says the camera is expected to be available to recycling centers in early 2017 and will be ready for the market at the end of that year.