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Newly launched InGaAs technology detects window of opportunity for plastic recycler

15.07.2009 Buhler Sortex applies InGaAs technology to create uniquely elegant solutions in uPVC recycling. Since 1947, Buhler Sortex has been a world leader in sophisticated optical sorting solutions for processors of a wide range of commodities and now has customers in over 140 countries. In an imaginative example of lateral thinking over 50 years ago, Buhler Sortex introduced these technologies to the plastics industry and they continue to apply their latest innovations to the evolving needs of this rapidly growing international market.

A leading plastic recycling company in the UK is applying Buhler Sortex’s unique Indium Gallium Arsenide (InGaAs) based technology to institute a profitable revenue stream from its Post Consumer uPVC window re-grind operation.

Post Consumer product comes from demolition properties and is cheap to buy, yet it presents many problems in processing. These include the isolation of black rubber seal fragments and, more importantly, the removal of white silicon from white uPVC window re-grind. In addition, the Post Consumer product frequently presents unexpected defects and contaminants. Surprises are to be expected.

Unless contaminants can be detected with certainty, profitable processing is a risky venture. But that certainty is now possible with the application of InGaAs technology in the SORTEX Z+ sorter.

InGaAs was developed originally for the space programme to distinguish between cultivated and uncultivated fields. It was quickly adopted for military use as it enables the distinction between foliage cover and other material to be made easily. Seizing on this capability, Buhler Sortex has applied the technology to cameras it has designed and incorporated into its SORTEX Z+ sorter.

Conventional sorters use cameras based on silicon technology that can detect energy only in the visible and IR or NIR spectrums, whereas sensors in InGaAs cameras can detect energy in the SWIR region.

As a result, materials such as plastic reflect energy very well at certain wavelengths. Importantly, white silicon is reflected at a different intensity from uPVC and so can be identified and removed easily. Black rubber seal fragments can, of course, be removed using visible cameras.

Buhler Sortex's customer also sorts a Jazz PVC product which has many colours that require separation. Colours which have a premium value can be isolated from those of less value using Buhler Sortex high resolution visible cameras.

Faisal Baig, Buhler Sortex Product Marketing Specialist said, “The customer is able to create a consistent revenue flow from a material which, in the absence of the SORTEX Z+, would be likely to go to landfill. There is no more versatile or efficient sorter for all types of recycled and virgin plastic applications in flake, granular or pellet form.”