Drum Pulper Screen Plate Blockage by Plastics for Paper Mills

In a paper mill machine, the pulper screen plate is essential for separating fibers from contaminants. When plastic pieces like film, hot melt adhesive, or pressure‑sensitive labels enter the system, they often become the main cause of blockage. The customer reports an 8.0 mm round hole screen plate being plugged by plastic sheets. Several factors contribute to this problem.

First, waste paper with high plastic content introduces soft, deformable impurities that are not easily broken down during pulping. Second, an 8.0 mm round hole has limited clearance for soft plastics, allowing them to wedge into the openings. Third, low pulping consistency (4‑5 percent) or short residence time reduces fiber‑to‑fiber friction, so plastics remain as large flakes when they reach the screen. Fourth, an improper gap between the rotor and the screen plate – especially with a Helisoft rotor if the gap is too wide – fails to force plastics through the holes. Finally, a screen plate without self‑cleaning design, such as a reverse taper or groove on the back side, makes it easy for plastics to lodge permanently. These factors together reduce the efficiency of your paper production equipment and cause unplanned downtime.

For immediate relief without stopping the paper making machine, operators can raise pulping consistency to 6‑7 percent to increase abrasive action, which helps tear plastic agglomerates. Longer pulping time also allows more complete dispersion before screening. If the system permits, high‑pressure water above 20 bar can be injected from the outside of the screen to flush out stuck particles. Reducing the intake of high‑plastic waste paper through better sorting also helps. For long‑term improvement, consider replacing the screen plate with a larger aperture – 10‑12 mm round holes or slotted types such as 12×40 mm elliptical openings, which allow soft plastics to pass more easily. A screen plate with reverse‑tapered holes, where the exit side is slightly larger than the inlet, reduces jamming. Some suppliers offer screen plates with serrated edges that cut plastic strips as they pass. Adding a coarse screen with 12‑15 mm holes upstream of the pulper discharge can separate large plastics before they reach the fine screen. Also check that the Conic Drum plastic cleaner is working properly to prevent recirculation of contaminants. If plastic problems persist, evaluating a different pulp and paper machinery type such as a drum pulper is a wise move.

Our ZG series drum pulper is designed to handle high plastic content without clogging. It operates at 14‑18 percent high consistency, gently pulping fibers while keeping impurities intact. The drum design has large screening area and fewer quick‑wear parts, dramatically reducing plastic‑related blockages. With production capacities from 70 to 1800 t/d and drum diameters from 2500 to 4500 mm, our drum pulper integrates seamlessly into your complete paper mill line. Contact Leizhan to upgrade your paper making line and eliminate screen plugging for good: leizhanworld@gmail.com