Nasszerkleinerung vs. Trockenzerkleinerung in einer PE-Folienwaschanlage

Dry Crushing: The Basics

Dry crushing, as the name suggests, involves shredding or granulating PE film without introducing water. The film, frequently contaminated with dirt, labels, and other debris, is fed directly into the crusher.

Vorteile:
Lower initial water consumption is the principal benefit. It also avoids the immediate production of contaminated wastewater that would require subsequent treatment. Additionally, dry crushing may place less demand on certain equipment, potentially extending maintenance intervals.

Disadvantage:
A significant drawback I’ve consistently noted is the increased wear and tear on machinery due to higher friction and heat during operation.

Best Suited For:
Dry crushing is generally more suitable for facilities handling relatively clean film or those operating under stringent water restrictions. It can also be ideal for pre-shredding applications, where an initial rough size reduction is sufficient.

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Wet Crushing: A Closer Look

Wet crushing incorporates water into the size-reduction process, where it functions as a lubricant, coolant, and initial cleaning agent.

Vorteile:
This method significantly reduces friction and heat build-up within the crusher, greatly enhancing blade life and reducing downtime and replacement expenses. The presence of water initiates the washing process early by loosening dirt and contaminants, leading to cleaner materials entering subsequent washing stages. Importantly, wet crushing effectively controls dust, resulting in a safer and more compliant working environment.

Nachteile:
Clearly, wet crushing involves higher initial water consumption. It also demands a robust wastewater treatment system to manage the contaminated water generated, adding operational complexity and cost.

Best Suited For:
Wet crushing is generally the preferred approach for most PE film washing lines, particularly when processing highly contaminated material. From my experience, the advantages in terms of equipment durability, material quality, and overall cleaning efficiency often outweigh the additional costs associated with water usage and wastewater treatment.

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Making the Right Choice: Key Factors

There is no one-size-fits-all solution when choosing the optimal crushing method. Consider the following:

• Contamination Level: Highly contaminated film typically benefits greatly from wet crushing. Although cleaner film could potentially suit dry crushing, you must still factor in increased equipment wear and tear.
• Water Availability and Cost: Restrictions on water use or high water expenses can make dry crushing an appealing option. However, you must account for potential increases in maintenance costs and possibly reduced output quality.
• Wastewater Treatment Capacity: Without adequate wastewater treatment capabilities, dry crushing might initially appear to be the only feasible choice. Yet, investing in an appropriate treatment system often yields long-term gains through improved efficiency and higher-quality output achievable with wet crushing.
• Durchsatzanforderungen: High-throughput operations generally favour wet crushing, owing to its efficiency and capacity to handle larger volumes of material effectively.
• End-Product Quality Requirements: If your goal is high-purity recycled PE flakes, wet crushing is almost invariably the better option. Its pre-cleaning effect significantly enhances the quality of the final product.

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Das Fazit

For optimal washing and cleaning of material, wet crushing is undoubtedly superior. It simultaneously lubricates and cleans, significantly extending the lifespan of machinery. While the costs associated with wastewater treatment cannot be overlooked, wet crushing still emerges as the most effective overall method in terms of quality, efficiency, and equipment durability.