Plastics Industry Silo Problems

Plastic granules and powder have properties that make silo storage challenging. Static electricity is a pervasive problem – plastic particles generate significant electrostatic charges during pneumatic transport and discharge, causing particles to stick to silo walls and to each other. Many polymers are thermoplastic, meaning they soften at elevated temperatures. Solar heating of metal silos can raise wall temperature sufficiently for granules along the wall to soften and stick. This is particularly problematic for polyethylene powder and PVC compounds. Additives such as colour masterbatches, stabilisers and fillers often have very different flow properties from the main polymer. Segregation in the silo can lead to uneven dosing and quality problems in the final product.

Static electricity in plastic silos is not just a flow problem – it is a safety risk. Fine plastic powder can form explosive dust-air mixtures, and electrostatic discharges can serve as ignition sources. Grounding of silos and transport equipment is fundamental but not always sufficient. Ionisation systems can neutralise static charges in the material flow. Anti-static additives in the plastic material can also reduce the problem. ATEX classification of plastic silos is required where explosive dust concentrations can occur. This affects choice of equipment, installation methods and maintenance procedures.

Plastic materials such as PVC, PE and PP can form stubborn wall deposits. The mechanisms vary: PE and PP stick through thermal softening, PVC can degrade and form hard coatings, and powder materials can compact under pressure. Colour masterbatches are particularly problematic because they often contain waxes and binders with low melting points. These can melt on warm silo walls and form a sticky layer that captures other particles. Cleaning of plastic silos requires care to avoid static discharges and to prevent contamination between different polymer types. Material residues from one polymer can cause quality problems in the next batch with a different material.

Insulation of silos reduces solar heating and temperature variations that contribute to thermal deposits. Interior coating with smooth, anti-static materials such as PTFE or special polymers can reduce wall adhesion. Air cannons and vibrators can prevent deposits but must be carefully sized in explosive environments. All flow aids in ATEX-classified zones must be certified for use in explosive atmospheres. Regular emptying and stock rotation prevents material from standing too long. The "first in, first out" principle is important for avoiding degradation and lump formation.

Mechanical cleaning is the most effective method for removing hard deposits in plastic silos. PVC deposits in particular can become extremely hard and require mechanical force for removal. Cleaning tools must be selected with contamination in mind – tools used in technical plastics production cannot have residues of other materials. Separate tool sets for food-approved plastic types are often necessary. Dust management during cleaning is critical due to explosion risk. All operations must follow ATEX guidelines and include adequate ventilation and grounding.

Blue Power has experience cleaning plastic silos for injection moulders, extrusion producers and masterbatch suppliers. We understand the special requirements for contamination-free and ATEX-safe operations that the plastics industry demands. Our mechanical cleaning methods effectively remove all types of plastic deposits without risk of cross-contamination. We adapt tools and procedures to your specific materials and quality requirements. Contact us for a no-obligation assessment of your plastic silos.