Ps Sorting Machine | AISORT
Application Overview — Plastic Recycling
PS Sorting in Modern Recycling Facilities
Polystyrene (PS) sorting addresses both expanded PS (EPS/XPS foam) and rigid PS (yogurt pots, CD cases, cutlery). While PS has lower recycling rates than PET or HDPE, it is increasingly targeted for recycling due to its high embodied carbon, lightweight nature (high collection cost per tonne), and emerging chemical recycling pathways that accept sorted PS as feedstock.
Material Characteristics and Sorting Challenges
PS sorting challenges: EPS foam has extremely low bulk density (10-30 kg/m³), making conventional conveyor-based sorting impractical without densification; rigid PS is often contaminated with food residues; PS can be confused with PVC by some NIR sensors due to spectral similarity in certain wavelength ranges; and the economic case for PS recycling depends heavily on collection density and proximity to reprocessing capacity.
Recommended Sorting Technology Stack
For rigid PS: NIR (PS identification, with careful calibration to distinguish from PVC and ABS) + RGB (color sorting) + density pre-separation (PS sinks in water, SG 1.04-1.06, separating from polyolefins). For EPS foam: cold compaction or thermal densification before sorting; then NIR + RGB of densified material. Throughput: 2-5 t/h for rigid PS, 0.5-2 t/h for EPS (pre-densification).
Performance Benchmarks
| Metric | Target |
|---|---|
| PS Purity | >95% |
| PVC in PS | <1% |
| Throughput | 2-5 t/h (rigid) |
| EPS Density Increase | 40-60:1 compaction |
These benchmarks represent achievable performance with modern sensor-based sorting equipment, assuming properly sized, well-maintained equipment operating on representative feedstock. Actual results depend on specific material composition, throughput, and operating conditions.