Ghidul complet pentru liniile de spălare a foliei de plastic: de la baloți murdari la fulgi puri

Bales of used plastic film—like LDPE agricultural film or post-consumer PP woven bags—hold significant value, but only if they can be transformed into a clean, pure raw material. This is where a Linie de spălare cu folie de plastic becomes essential. It’s a sophisticated system of machines working in concert to shred, scrub, separate, and dry dirty plastic, preparing it for its new life in pellet form.

A well-designed washing line is the heart of any successful film recycling operation. It’s the critical step that turns contaminated waste into high-quality, marketable plastic flakes ready for pelletizing and manufacturing.

Step 1: Size Reduction — The Critical First Cut

Before you can wash the film, you must break it down into smaller, manageable pieces. This initial step is crucial for several reasons:

• Prevents Clogs: It stops whole plastic bags from tangling around rotors and shafts, which would cripple output and pose a safety risk.
• Increases Surface Area: Smaller pieces have more surface area exposed for a more effective and thorough cleaning.
• Ensures Smooth Transport: Uniformly sized fragments flow easily between different machines in the line.

For this task, you have two primary options: an industrial shredder or a wet crusher (granulator).

Option A: The Heavy-Duty Shredder

A shredder is a low-speed, high-torque beast. Its powerful blades, mounted on slow-rotating shafts, can tear through entire bales of compressed film, breaking them down into palm-sized or larger pieces (typically 1-5 inches). Because it operates at low speeds, it generates minimal noise and dust.

Key Advantage: A shredder’s ability to process entire, unsplit bales of film is its main selling point. For high-volume recycling centers looking to maximize automation and reduce manual labor, a shredder is indispensable.

Option B: The High-Speed Crusher (Granulator)

In contrast, a crusher (or granulator) operates at much higher speeds (200-800 RPM). As rotor knives spin past stationary bed knives inside a cutting chamber, they shear the plastic into smaller, more uniform flakes. The material can only exit once it’s small enough to pass through a screen at the bottom.

For washing lines, a granulator umed is highly recommended. It continuously sprays water into the cutting chamber, achieving two goals at once: it size-reduces the material and performs an initial pre-wash on the dirty film. The water also lubricates the blades, reducing heat and wear.

Shredder vs. Crusher: Which is Right for You?

The best choice depends on your raw material and operational goals. Many high-performance lines use both: a shredder for primary breakdown of bales, followed by a wet crusher for finer grinding and pre-washing.

Caracteristică	Tocător	Concasor (Granulator)
Material de intrare	Whole bales of film	Loose film (bales must be broken first)
Operation	Low-speed, high-torque	High-speed, lower-torque
Dimensiune de ieșire	Larger, less uniform pieces	Smaller, more uniform flakes
Noise & Dust	Minimal noise and dust	Higher noise and dust (mitigated by enclosures)
Contaminant Tolerance	Excellent. Handles dirt, sand, and some hard objects well.	Poor. Easily damaged by hard contaminants like rocks or metal.
Întreţinere	More complex, blade changes are time-consuming.	Simpler, blades are easier and faster to change.
Best For…	High-volume, automated lines or processing highly contaminated film.	Lower volume lines or as a secondary grinder for uniform output.

Step 2: High-Intensity Washing & Scrubbing

Șaibă cu frecare de mare viteză

After the initial size reduction, the real cleaning begins. A high-speed friction washer is designed to vigorously scrub the plastic flakes. Its core is a long, angled shaft with paddles rotating at over 1,000 RPM.

As material enters the lower end, the high-speed paddles create intense friction between the plastic flakes, scrubbing off stubborn dirt, grime, and paper labels. Water is continuously sprayed inside, and forța centrifugă flings the dirty water and contaminants out through a surrounding screen. The clean material is pushed up the angled chamber and discharged from the top.

This machine is especially effective at removing paper and cardboard contamination, which is broken down into a pulp and easily expelled.

Step 3: Separation & Purification

Rezervor de separare chiuvetă-plutitor

The sink-float tank is a master of separation, serving two functions:

1. Further Cleaning: It allows the plastic flakes to soak, loosening any remaining dirt.
2. Density Separation: It separates the desired plastic from heavier contaminants.

The principle is simple: plastic film (like PE and PP) is less dense than water (density < 1.0 g/cm³), so it floats. Heavier contaminants like sand, rocks, glass, and metal sink to the bottom.

Slowly rotating paddle drums skim the clean, floating plastic flakes off the surface of the water and move them to the next stage. The contaminants that collect at the conical bottom of the tank are periodically removed by a screw conveyor or pneumatic valve.

Alternative: Separator ciclonic

While more common in Reciclarea sticlelor PET, hydrocyclone separators can also be used for film. They use high-pressure water flow to create a centrifugal vortex that separates materials by density with even greater efficiency than a standard float tank.

Step 4: Drying & Dewatering

The Final, Crucial Drying Stage

Drying is the last and one of the most critical steps. To avoid issues like air bubbles and imperfections during extrusion pelletizing, the moisture content of the final film flakes must be reduced significantly, ideally to under 15%. There are two primary methods to achieve this.

Method 1: Centrifugal Dewatering + Hot Air Drying

This two-stage process is highly effective.

1. Dewatering Machine: The wet flakes first enter a centrifugal dewatering machine (structurally similar to a friction washer). It spins at high speeds, using centrifugal force to sling the majority of the water off the flakes, typically reducing moisture to the 20-30% range.
2. Hot Air Drying: The dewatered flakes are then conveyed through a series of tubes where they are mixed with hot air. This evaporates the remaining moisture before the flakes are collected in a cyclone separator.

Method 2: Screw Press Dryer

A screw press offers a more economical, single-step drying solution. It uses immense physical pressure to literally squeeze water out of the plastic flakes.

The core of the machine is a large, tapered screw. As wet material is fed in, the decreasing space within the screw flight compresses the plastic, forcing water out through small holes in a surrounding screen. This mechanical squeezing can effectively reduce moisture content to the target level without the energy costs of hot air dryers.

How to Customize Your Perfect Film Washing Line

There is no “one-size-fits-all” solution. The ideal configuration of your washing line depends entirely on two factors:

• The type of plastic film you are processing.
• The level and type of contamination.

For example, a basic line for relatively clean LDPE 98/2 film might consist of a wet crusher, a float tank, and a screw press dryer.

However, if you’re processing heavily soiled agricultural film, you’ll need a more robust system. You might add a tocător before the crusher to protect the blades and handle baled material. You would likely incorporate one or even two high-speed friction washers to ensure a deep clean.

Conclusion: Your Partner in Clean Plastic
A plastic film washing line is a dynamic system where each component plays a vital role in the journey from waste to value. Understanding the function of each machine—from shredders and friction washers to separation tanks and dryers—is the first step toward building a line that is efficient, effective, and profitable. Because the performance of equipment can vary significantly, the best course of action is to consult with an expert to configure a system that is perfectly tailored to your specific raw materials and end-product goals.