Sink-Float Tank System for PET Recycling
The sink-float separation tank is a core purification stage in PET bottle recycling, designed to remove floating PP and PE contaminants from heavier PET flakes through density-based separation in water.
It improves final flake purity, stabilizes downstream hot washing and drying, and supports higher-value rPET output.
- Separates PET from PP, PE, and label residues by density.
- Provides extra soaking and washing time during purification.
- Available in custom lengths and widths for different throughput targets.
Working Principle for PET Flake Purification
Water acts as the separation medium: heavier PET sinks while lighter caps and label fragments float to the surface for removal.
PET Flakes Sink
Because PET is denser than water, the valuable flakes settle to the bottom and are collected by the discharge conveyor.
Contaminants Float
PP and PE bottle caps, label pieces, and other light contaminants remain on the surface for removal.
From Common Separation Problems to Stable PET Purification
The tank configuration should address the contamination, residence-time, material-flow, and maintenance issues that affect PET flake purity.
PP and PE Contamination
Caps, rings, and label fragments can remain mixed with PET flakes after crushing and initial washing.
Water-density separation allows heavier PET to sink while lighter PP and PE fractions float for controlled removal.
Insufficient Residence Time
A short separation path may discharge material before PET flakes settle and floating contamination is removed effectively.
Tank lengths from 4 to 6 meters provide more soaking and settling time for a more stable separation process.
Unstable Material Flow
Uneven feeding or discharge can create material accumulation and inconsistent purification results.
Screw conveyors and rotating drums maintain continuous movement of sinking PET and floating contaminants.
Corrosion and Difficult Cleaning
Continuous water exposure and trapped residues can increase maintenance work and shorten equipment life.
Type 304 stainless steel on key wetted sections supports corrosion resistance and practical routine cleaning.
Key Advantages
A critical separation stage for improving rPET flake quality before drying, storage, or pelletizing.
High PET Purity
Removes a significant amount of PP and PE contamination from bottle caps and label fractions.
Dual-Function Process
The system separates by density while also providing an additional wet cleaning stage.
Optimized Soaking Time
Tank lengths from 4 to 6 meters allow more complete settling and more stable separation.
Durable Construction
Type 304 stainless steel is used on key internal sections for corrosion resistance and long service life.
Typical PET Recycling Applications
This tank is used where heavier PET flakes must be separated from floating PP, PE, cap, ring, and label contamination before final purification.
Post-Consumer PET Bottle Flakes
PET flakes sink while PP and PE bottle caps, rings, and light label fragments float for removal.
Before Hot Washing
Removing floating polyolefin contamination first reduces the impurity load entering the hot washer.
Before Drying & Sorting
Cleaner PET flakes provide more stable feed for dewatering, thermal drying, and optical sorting equipment.
High-Purity rPET Feedstock
Supports PET flake preparation for fiber, strapping, sheet, pelletizing, and suitable high-purity recycling projects.
What to Compare When Selecting a PET Sink-Float Tank
Compare measurable equipment and process details against your feedstock, throughput, workshop layout, and downstream quality target.
| Selection Factor | What to Confirm | Why It Matters |
|---|---|---|
| Tank Length | Available residence time and settling distance under the planned feed rate. | Insufficient length can reduce separation stability at higher throughput. |
| Interior Width | Usable tank width relative to material volume and required kg/h. | Affects material distribution, water flow, and production capacity. |
| Wetted-Part Material | Stainless-steel grade used for sections continuously exposed to water. | Influences corrosion resistance, cleaning effort, and service life. |
| Discharge Design | Separate removal systems for sinking PET and floating PP/PE contamination. | Stable discharge helps prevent remixing and material accumulation. |
| Drive Configuration | Motor power, screw conveyor arrangement, and rotating drum control. | Must match material load without creating unstable flow or unnecessary energy use. |
| Maintenance Access | Access for sediment removal, cleaning, inspection, and conveyor service. | Practical access reduces cleaning time and unplanned shutdowns. |
| Line Integration | Connection with upstream washing and downstream dewatering, drying, or sorting equipment. | Correct elevations and feed rates support continuous PET recycling operation. |
Technical Specifications for PET Recycling
| Specification | Details |
|---|---|
| Interior Width | 1500 mm to 2000 mm |
| Total Length | 4 to 6 meters |
| Interior Material | Type 304 stainless steel |
| Exterior Frame | Carbon steel |
| Screw Conveyor Motors | 5.5 kW + 3.7 kW |
| Rotating Drum Motors | 0.37 kW + 2.2 kW |
Warranty & Installation
1-Year Warranty
Includes core equipment coverage with spare-parts support and technical follow-up.
Installation Support
Engineers can assist with site layout, setup, and commissioning to optimize separation performance.
Frequently Asked Questions
The primary contaminants are plastic bottle caps and label fragments made from PP or PE. These float while the heavier PET flakes sink.
A longer tank provides a longer residence time in water, allowing PET flakes to settle more completely and improving separation efficiency.
Yes. Tank dimensions and motor configurations can be adjusted to match throughput requirements and facility layout.
Inquire Now
Send your throughput target and facility requirements to receive pricing, lead time, and a recommended tank configuration.
