SORTING | TECHNOLOGY
NIR and robotic sorting technologies are raising the yield from mixed material streams, while a new process using Raman spectroscopy is targeting black plastic waste. By Mikell Knights
Innovation in plastics sorting techniques
The landscape of sorting technologies continues to evolve with innovations designed to generate more highly uniform fractions of a growing range of materials from increasingly mixed waste plastics. New and advanced optical and robotic sorting, developments in Artificial Intelligence (AI) and machine learning, and partnerships within the plastics recycling and sorting value chain drive the latest innovations. Near-infrared (NIR) technology has been the
focus of development by many companies working in the optical sorting sector. But multinational corporation Canon Global has developed a different process for identifying and sorting plastic materials of black shades and black plastic pieces mixed with those of other colours, which have been difficult to separate. “Nowadays, NIR spectroscopy is the dominant method used in plastics sorting by material, however, pieces made of black plastics, which are used in many household electronics, automobile upholstery and other items, cannot be
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sorted using this method because they do not allow visible light to penetrate nor reflect. As a result, such plastics are instead reused as combus- tible fuel,” says Canon Global. The company says this tends to be the case with various types of materials such as ABS and PP used in a wide range of everyday applications. Canon Global’s sorting development is based on the use of Raman spectroscopy, a detection method that utilises laser light to illuminate plastic waste to obtain molecular information about the material, making possible the material detection of black plastic pieces. When a substance is illumi- nated with laser light, it emits Raman scattered light which contains a great deal of information regard- ing the chemical makeup of the material, says Canon Global. The components comprising the material can be identified by analysing the Raman scattered light. Raman spectroscopy is typically used for
measuring organic matter but is suitable for use in September 2023 | PLASTICS RECYCLING WORLD 13
Main image: Sorting
technologies are becoming more and more accurate
IMAGE: TOMRA
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