Introduction: The Untapped Value in Problematic Waste
The market for post-consumer recycled (PCR) resins is expanding rapidly, driven by corporate sustainability goals and government mandates. Yet, a significant portion of valuable feedstock, particularly post-consumer LDPE/LLDPE film, remains a challenge for recyclers. The reason? Heavy contamination. Bales of post-consumer film are often a complex mix of the target plastic, paper labels, adhesive residues, heavy printing inks, and moisture.
Attempting to process this material with a standard pelletizer inevitably leads to frequent downtime, high maintenance costs, and a final product riddled with impurities, rendering it low-grade or even unusable.
A simple machine is not the answer. The solution lies in a systematic, multi-stage approach that addresses each contaminant individually before the material ever reaches the extruder. This guide details the Rumtoo integrated washing and pelletizing system, engineered specifically to transform this challenging waste stream into high-quality, profitable PCR pellets.
Chapter 1: The Anatomy of Contamination
To defeat the enemy, one must first understand it. The primary contaminants in post-consumer film each pose a unique technical challenge:
- Paper Labels & Adhesives: During extrusion, paper fibers do not melt; they carbonize. This results in black specks throughout the pellets. Furthermore, pulped paper can clog melt filters in minutes, causing constant production stoppages. The associated adhesives can degrade and further discolor the final product.
- Heavy Printing Inks: Many flexible films feature heavy ink coverage. These inks contain volatiles that, when heated in the extruder, can create porosity (voids) in the pellets. They also contribute to discoloration and odor in the final resin.
- Moisture & Organic Residue: Any moisture trapped in the material will turn to steam in the extruder, leading to voids and “silver streaks” in the pellets. This dramatically compromises the material’s structural integrity and processing stability in downstream applications.
Chapter 2: The Rumtoo Systematic Solution: A Stage-by-Stage Breakdown
Our system is designed as a production line where each stage prepares the material for the next, ensuring only clean, dry plastic enters the final, critical pelletizing phase.
Stage 1: Size Reduction & Contaminant Liberation (HD Series Heavy-Duty Shredder)
The process begins by feeding entire bales into a high-torque, low-speed shredder. Unlike a granulator, a shredder is designed to handle foreign objects and heavy contamination without catastrophic blade failure. Its primary goal is to rip open the film and break it into 1-2 inch flakes, “liberating” the dirt and paper from the plastic surfaces, making them accessible for the washing stage.
Stage 2: High-Impact Washing & Purification (Friction Washer & Sink-Float Tank)
This is the core of the cleaning process.
- Friction Washer: The shredded flakes are fed into a high-speed friction washer. The rotor, spinning at over 1,000 RPM, creates intense mechanical scrubbing between the plastic flakes. This action acts like a pulping machine, breaking down paper labels into a fine slurry and scouring away dirt and grime.
- Sink-Float Separation Tank: The mixture is then submerged in a large water tank. The lighter PE/PP plastic flakes (density <1.0 g/cm³) float, while the heavier, water-logged paper pulp, sand, and other solids (density >1.0 g/cm³) sink to the bottom and are automatically removed by a screw conveyor. This simple yet highly effective density separation is critical for removing the bulk of the paper contamination.
Stage 3: Aggressive Dewatering & Drying (Screw Press & Thermal Dryer)
The clean flakes are now saturated with water. A two-stage drying process is employed:
- A Screw Press Dewatering Machine mechanically squeezes the flakes, expelling the majority of free water and reducing moisture content to approximately 15%.
- A Thermal Drying System then uses hot air to evaporate the remaining moisture, bringing the final content to well below the 5% threshold required for quality extrusion.
Stage 4: Final Extrusion & Polishing (ML Series Pelletizing System)
Even after extensive washing, trace impurities can remain. The final pelletizing stage is designed to handle these, ensuring a premium final product.
- Vented (Degassing) Screw Barrel: The extruder is equipped with at least one vacuum degassing zone. As the plastic melts, this vacuum port sucks away any remaining moisture vapor and volatile compounds from the printing inks, preventing bubbles and voids in the pellets.
- High-Capacity, Dual-Station Screen Changer: This is the final quality gatekeeper. Before the molten plastic reaches the pelletizing die, it passes through this filter. Our dual-station, non-stop screen changer allows an operator to change a clogged filter screen on one station while the other continues to operate, ensuring continuous production without downtime—a critical feature when processing material with residual impurities.
Chapter 3: The Result: From Contaminated Waste to Premium Feedstock
By implementing this systematic approach, recyclers can achieve a dramatic transformation.
| Parameter | Before Processing | After Rumtoo System |
| Contamination Level | > 30% (paper, dirt) | < 0.5% |
| Moisture Content | Variable ( >10% ) | < 3% |
| Final Pellet Quality | N/A | Uniform, clean, minimal voids |
| Market Value | Low / Negative (disposal cost) | High (premium PCR resin) |
The resulting high-quality pellets are suitable for a wide range of applications, including manufacturing new film, injection molding pipes and pallets, and wood-plastic composites, commanding a significantly higher price in the market.
Conclusion: A System is More Than the Sum of Its Parts
Successfully recycling heavily contaminated post-consumer film is not about having one “good” machine. It is about an intelligent, integrated system where each component is designed to solve a specific problem, preparing the material for the next stage. This systematic process de-risks the operation, maximizes uptime, and is the only way to reliably produce a high-quality final product from a challenging raw material.
At Rumtoo, we don’t just sell machines; we engineer end-to-end solutions.
Do you have a challenging stream of contaminated plastic film? Contact our technical team today to discuss a customized system solution and receive a free, no-obligation material analysis.
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