A Stacks Sizer polyurethane mesh panel can blind during wet screening when fine particles, clay and near-size material stick to the panel or become trapped in its apertures. Contributing factors include high feed concentration, poor water distribution, unsuitable aperture geometry, excessive bed depth, incorrect vibration settings and worn panels. Blinding is not necessarily a sign that the PU material is defective — it is usually the interaction between feed characteristics, water conditions, aperture design and screen operation. Diagnose the blockage before changing the panel.

Key Takeaways

• Blinding and pegging are different mechanisms. Blinding is a film of adhered fines; pegging is discrete particles wedged in apertures. The corrective actions differ.

• Process causes usually come first. Clay content, spray distribution, feed rate and bed depth account for most Stack Sizer blinding.

• Blocked nozzles mimic panel failure. A localised blind zone under a blocked spray nozzle looks exactly like a defective panel.

• Upstream changes matter. A shift in GRINDING performance can increase the fines or near-size fraction reaching the deck.

• Panel design is the second lever. Aperture taper, slot orientation, hardness and thickness matter after process conditions are correct.

• Extra water is not a fix. Excess water changes slurry behaviour and affects downstream processing.

Summary Table

Definition

Blinding is the covering of screen apertures by adhered fines, clay or sticky deposits, reducing effective open area without necessarily filling individual openings.

Pegging is the wedging of individual near-size particles inside apertures, where they remain trapped despite vibration.

A Stack Sizer PU mesh panel is a polyurethane screening panel used in multi-deck high-frequency fine wet screening machines. It is typically compared against WIRED & STEEL SCREEN MESH and specialised POLYURETHANE FINE SCREEN PANEL configurations.

Working Principle

Stack Sizer blinding develops through several distinct mechanisms, and the diagnostic value lies in separating them.

Clay adhesion. Clay-bearing feed mixed with water forms sticky deposits on the polyurethane surface. Fines accumulate around apertures and gradually cover them. The blocking pattern is typically a continuous film rather than discrete plugs.

Near-size pegging. Particles close to the aperture dimension enter an opening but fail to pass through, wedging in place. The pattern is discrete blocked holes with particles protruding, while adjacent apertures remain open.

Wash water deficiency. Water disperses particles and carries fines through apertures. Insufficient pressure, blocked nozzles or uneven coverage creates localised zones where fines accumulate instead of passing.

Feed overload and thick bed. Stack Sizer performance depends on uniform, thin slurry layers. Excessive feed rate or uneven distribution produces a thick bed at the feed end, which prevents particles from contacting the screening surface.

Aperture mismatch. Straight-sided apertures retain near-size particles more readily than tapered or relieved profiles. Slot orientation also affects passage and drainage behaviour.

Panel stiffness mismatch. A panel that is too rigid does not move enough to release trapped particles. A panel that is too soft deflects under load, accelerating wear and reducing screening stability.

Effective open area during operation — not nominal open area on a drawing — determines whether the deck performs.

Benefits

• Higher effective open area when blinding is controlled rather than masked.

• Improved fine separation because undersize reports correctly to the undersize stream.

• Reduced carry-over into downstream classification and dewatering.

• Lower cleaning frequency and less unplanned downtime.

• Better panel life when aperture and hardness match the actual duty.

• Measurable cost benefit when assessed against downtime and cleaning labour.

Applications

• Fine classification ahead of CLASSIFICATION circuits.

• Desliming duties where clay and fines are present.

• Wet sizing in iron ore, copper ore, gold and base metal circuits.

• Industrial minerals processing where tight fine cuts are required.

• Tailings duty where fines content is high and moisture unavoidable.

• Coal preparation where wet screening and drainage occur together.

These duties sit downstream of GRINDING and upstream of classification, dewatering and flotation. A blinded fine screen propagates mis-sized feed into every subsequent stage.

Material Comparison

Application Comparison

Industry Application Matrix