To overcome feeding and reactor coking issues caused by tangled plastic waste, the facility integrates two Harden DWS shredding and sorting systems.

 

By utilizing a three-stage automated process (primary shredding, wind shiftering, magnetic separation, and single-shaft fine shredding), the system converts complex film waste into standardized feedstock (<30 mm particle size, >95% compliance rate), securing the essential first stage of large-scale chemical recycling.

 

1. Project Overview & Operational Metrics

Located in England, this facility addresses the long-standing challenge of processing light, highly contaminated post-consumer plastic films within the UK recycling infrastructure.

Total Investment: £125 million

 

Phase 1 Processing Capacity: 60,000 tons/year of waste plastic film

 

• Annual Output: Approximately 40,000 tons/year of pyrolysis oil

• Environmental Impact: Estimated reduction of 170,000 tons of CO2 emissions annually upon full operation

 

2. Technical Challenge: Upstream Pre-Treatment in Chemical Recycling

Chemical pyrolysis relies on thermochemical decomposition at the molecular level, requiring strict uniformity, controlled particle sizing, and low contaminant levels in the incoming feed:

 

• Particle Size Disparities: Coarse, non-uniform shredding results in incomplete pyrolysis for oversized pieces and excessive carbonization (coking) for over-shredded fines.

• Material Entanglement: Flexible agricultural and packaging films tend to wrap around cutter shafts in conventional shredders, creating dense agglomerates that cause uneven heat distribution and reactor fouling.

 

Reactor performance depends on upstream feed preparation. Without fine pre-treatment, un-liberated contaminants and irregular feedstock cause reactor clogging, accelerated catalyst wear, and increased operational downtime.

 

3. Harden DWS Pre-Treatment System: Engineering Specifications & Performance

 

Summary & Key Specifications: Harden delivered two complete DWS shredding and sorting pre-treatment lines for the project.

 

The system uses a three-stage automated process—combining primary shredding, air classification, magnetic separation, and fine shredding—to transform bundled film waste into homogenous, low-ash feedstock for continuous pyrolysis.

 

Below is the breakdown of its core technical specifications and operational impacts:

 

Stage 1: Two-Shaft Primary Shredding

System Function: Performs initial volumetric reduction of bundled waste films and resolves material wrapping trends. 

 

Stage 2: Wind Shiftering & Magnetic Separation

System Function: Removes heavy inert fractions, gravel, sand, and ferrous contaminants from the plastic stream.

 

Stage 3: Single-Shaft Fine Shredding

System Function: Reduces material to a uniform particle size distribution suitable for pyrolysis reactor feeding.

 

Core Performance Data

• Particle Size Precision: <30 mm Output Size (>95% Compliance Rate)

• Operational Impact: Eliminates oversized fragments and minimizes fines, preventing reactor coking and carbonization.

• Processing Capacity: 10 – 20 Tons / Hour (Per Line)

•  Operational Impact: Matches the continuous feed requirements of 10,000-ton scale commercial pyrolysis plants.

•  Maintenance & Tool Lifespan: ~30% Longer Cutter Service Life

•  Operational Impact: Patented tool geometry and automated overload protection reduce wear-part costs per ton by approximately 18%.

• Automation & Control: AI Smart Control System

• Operational Impact: Automatically adjusts shaft rotation speed and feeding rates based on real-time motor load, enabling continuous operation with minimal manual clearing.

 

4. Pre-Treatment Workflow for Pyrolysis Feedstock

 

Pre-Treatment Workflow & System Logic: Pre-treatment is a fundamental engineering requirement for chemical plastic recycling.

 

Inadequate contaminant removal directly leads to downstream reactor blockages, higher maintenance costs, and reduced oil yields.

Here is the step-by-step pre-treatment workflow and its system logic:

 

Step 1: Primary Bounded Film Shredding

• System Logic: Bales of flexible plastic films are ripped open and primary-shredded to break up dense clusters.

• Downstream Value: Prevents material bridging and ensures an even flow into sorting equipment.

 

Step 2: Automated Air & Magnetic Decontamination

• System Logic: Inline magnetic separators extract ferrous metals, while air classifiers remove heavy stones and inert debris.

• Downstream Value: Protects downstream fine shredding blades and reduces ash content prior to reactor charging.

 

Step 3: Precision Fine Shredding & Reactor Feeding

• System Logic: Single-shaft refiners shred the cleaned plastic stream down to <30 mm uniform particles.

• Downstream Value: Delivers a consistent, low-ash, narrow-spectrum feedstock that optimizes thermal transfer inside pyrolysis reactors.

 

5. Conclusion

Industrializing chemical plastic recycling requires strict pre-treatment standards. From commercial projects in Asia to benchmark recycling facilities in Europe, Harden provides engineered shredding and separation systems capable of delivering millimeter-level particle precision at multi-thousand-ton annual capacities.

 

By producing standardized feedstock within the 20–40 mm range, advanced pre-treatment technology enables chemical recycling facilities to achieve predictable yields, lower operational risk, and establish reliable plastic-to-oil production lines globally.