NIR (Near-Infrared) optical sorters identify and separate materials by molecular composition. The technology distinguishes different types of plastic (PET, PE, PP, PVC, PS), paper, wood, and organic materials at high speed, even when visually identical.
How it works
Material passes in a single layer on a high-speed conveyor. Near-infrared sensors illuminate each particle and analyze its reflection spectrum. The software compares against a reference library and, within milliseconds, triggers compressed air valves that selectively eject target particles.
Applications
Plastic separation by polymer type in recycling plants
Removal of organic contaminants from recyclable fractions
RDF classification by calorific value (separation of inerts and PVC)
Purification of paper and cardboard fractions
Separation of treated wood from clean wood
Limitations
NIR does not work well with dark or black materials (they absorb infrared radiation), wet materials or those with contaminated surfaces, and very small or overlapping particles. Each application has an optimal point for particle size, speed, and preparation that must be validated under real conditions.
The decision to include NIR in the line depends on economic analysis: does the gain in purity and recovered fraction value justify the investment? This calculation is made with real composition data, market prices, and volumes — not from manufacturer catalogs.