Screen performance issue: when is a screen said to be “blinded”?

Introduction / Context:
Screen blinding is a common operational problem that lowers efficiency by blocking apertures. Recognising the correct definition helps troubleshoot capacity shortfalls and coarse carryover.

Given Data / Assumptions:

• Sizing screen with fixed apertures.
• Mixture containing near-size particles and possibly sticky fines.

Concept / Approach:
“Blinding” refers specifically to clogging of apertures by particles or agglomerates. With holes blocked, true open area falls, the probability of passage drops, and both capacity and separation sharpness deteriorate. Misplacement of sizes between fractions is a symptom—not the definition—of blinding or other faults.

Step-by-Step Solution:
Define blinding: plugging/bridging of apertures.Understand consequence: reduced open area and efficiency.Select the option that states “apertures plugged with solids.”

Verification / Alternative check:
Anti-blinding devices (ball decks, sliders, ultrasonics) and wet screening mitigate true blinding by restoring open area.

Why Other Options Are Wrong:
Presence of wrong-size material in streams is an effect, not the definition.Increased capacity is the opposite of what blinding causes.

Common Pitfalls:
Confusing blinding with pegging (individual near-size wedges); both reduce open area, but blinding is more general pore blockage.

Final Answer:
the screen apertures are plugged with solid particles.