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At the heart of every modern recycling plant is an optical sorter – a machine that sees, identifies and separates materials faster than any human could.
If there is one piece of equipment that defines a modern recycling facility, it is the optical sorter. These machines are responsible for the high-speed, high-accuracy material separation that makes large-scale recycling economically viable – and understanding how they work helps explain why recycling outcomes vary so much from one facility to another.
An optical sorting machine is a piece of industrial equipment that uses sensors – cameras, near-infrared detectors, or other optical technologies – to identify the material composition, colour, shape or size of objects moving along a conveyor, and then physically separates them based on that information, typically using bursts of compressed air. The "optical" in the name refers to the use of light-based sensing to make these identifications, as opposed to mechanical sorting methods like screens or magnets.
Material is fed onto a conveyor belt and spread into a thin, even layer to ensure individual items can be scanned separately. As each item passes under the sensor array, the machine captures data – for example, how the material reflects near-infrared light, which varies depending on its chemical composition. This data is processed in real time by classification software, which determines what the object is and whether it should be ejected from the main material stream. A fraction of a second later, as the item reaches the end of the conveyor, a precisely targeted jet of air ejects it into a separate collection chute – while everything else continues along its original path.
Different sensor technologies suit different sorting tasks. Near-infrared (NIR) sorters are widely used for plastics, identifying polymer types such as PET, HDPE, PP and PVC based on their spectral signatures. Visible light / colour cameras are used for sorting materials like glass by colour, or for detecting visual contaminants. Hyperspectral imaging combines many wavelengths of light to provide even more detailed material identification, useful for distinguishing closely related materials. Each of PICVISA's product lines – ECOGLASS, ECOPACK, ECOFLAKE and ECOSORT TEXTIL – combines these sensor types in configurations tuned to the material stream it is designed for.
Traditional sorting relies on mechanical properties – size via screens, density via flotation, magnetism via magnets – or on manual labour, where workers visually identify and remove items by hand. Optical sorters add a layer of sensing that can distinguish materials based on properties invisible to mechanical systems and far more consistent than human judgement, particularly at the speeds modern recycling lines operate at.
The benefits compound across a facility: higher recovery rates, since sensors can detect materials that would otherwise be missed; higher purity of sorted output streams, which commands better prices; reduced labour requirements for repetitive sorting tasks; and continuous operation at speeds and consistency levels manual sorting cannot match.
As demand grows for recycled content in everything from packaging to textiles to construction materials, the purity and volume of recovered material that optical sorting can deliver becomes a competitive factor – not just an environmental one. Facilities equipped with effective optical sorting can supply higher-grade recycled materials to a wider range of buyers, capturing more value from the same input stream.
Optical sorting continues to evolve, with AI and machine learning improving classification accuracy over time as systems are exposed to more material, and sensor fusion – combining multiple sensor types in a single machine – enabling more nuanced sorting decisions. As these technologies mature, the range of materials that can be reliably separated at scale continues to expand, pushing recycling rates higher across an increasing number of material streams.
Explore PICVISA optical sorting solutionsGet in touch with our team to discover how PICVISA's optical sorting and robotics solutions can fit your recycling operation.