The textile recycling industry is shifting from “downcycling” (insulation/rags) to “circularity” (fiber-to-fiber). This shift demands a radical change in shredding technology. A machine that makes rags cannot prepare feedstock for a chemical depolymerization reactor. This guide explores the pre-processing innovations required for modern textile recovery.
Related equipment: textile waste single shaft shredder.
1. The Feedstock Gap: Fluff vs. Chips
Mechanical Recycling (Spinning)
- Goal: Retain max fiber length (>15mm).
- Technology: Garnett-style single-shaft shredders with tearing pins.
- Innovation: Soft-Start High-Torque Drives that gently pull fabrics apart at low speeds (<60 RPM) to minimize fiber breakage and friction heat (which melts Polyester).
Chemical Recycling (Depolymerization)
- Goal: Maximize surface area for chemical reaction.
- Requirement: Uniform, dense “chips” (e.g., 10mm x 10mm). Fluff causes “bridging” in hoppers and floats in solvents.
- Technology: Double-Cut Granulators. A secondary granulator with a “guillotine” rotor cuts the pre-shredded textile into precise squares, increasing bulk density from 40kg/m³ to 150kg/m³.
2. Automated Sorting (NIR)
You cannot rely on garment labels (they are often wrong).
* Innovation: Hyperspectral NIR Cameras mounted over the shredder infeed conveyor.
* Function: Detects the precise Polyester/Cotton ratio (e.g., 60/40 vs 50/50) in milliseconds.
* Action: Air jets divert non-compliant items (e.g., all-nylon items in a cotton line) before they enter the shredder.
3. The “Hard Part” Problem: Zippers & Buttons
Zippers (Brass/Alu) and Buttons (Thermoset Plastic) destroy fine shredder blades.
* Old Method: Manual removal (too expensive).
* New Method: Hammer Mill Liberation.
* After pre-shredding to 50mm, the textile is passed through a high-speed Hammer Mill.
* The impact shatters buttons and detaches zippers from the fabric.
* A downstream Eddy Current Separator and Zig-Zag Air Classifier then remove the heavy metal/plastic fragments, leaving pure fiber.
4. Dust Control: The Microfiber Threat
Polyester microfibers are explosive (Kst > 0) and a respiratory hazard.
* Innovation: Negative Pressure Cutting Chambers.
* The shredder rotor is enclosed in a vacuum-sealed housing.
* Dust is extracted at the source (the cutting point) rather than allowing it to float into the room.
* This improves sensor reliability (no dust on optical lenses) and prevents cross-contamination of colors.
Conclusion
The future of textile recycling is not just “shredding”—it is fractionation. Buying a general-purpose shredder for sophisticated textile recovery often produces inconsistent feedstock and poor downstream yields. You should engineer the line for your specific end-product: Fiber (Mechanical) or Monomer (Chemical).
References
[1] “Guide to Recycled Materials (GRS-202),” Textile Exchange. Guide to Recycled Materials (GRS-202)
[2] “Automated Sorting Technologies,” Recycling International. Automated Sorting Technologies
