How does screen effectiveness (separation efficiency) trend as screen capacity (throughput) is increased substantially?

Introduction / Context:
Screening efficiency balances throughput against probability of particle presentation to the apertures. Pushing higher capacity typically compromises the probability that near-size particles find and pass through openings.

Given Data / Assumptions:

• Same screen area and aperture.
• Higher feed rate increases bed depth and velocity.

Concept / Approach:
As loading rises, particle bed deepens and stratification worsens; near-size particles have fewer opportunities to contact openings, and blinding can increase. Thus, effectiveness (the sharpness/accuracy of separation) declines with increasing capacity at fixed area.

Step-by-Step Solution:
Increase feed → deeper bed, shorter residence.Lower probability of passage for near-size fractions.Efficiency decreases.

Verification / Alternative check:
Manufacturer capacity charts show trade-off between capacity and efficiency.

Why Other Options Are Wrong:
Unchanged/Increases: contradicts the fundamental capacity–efficiency trade-off.Exponential decrease: too specific; the trend is monotonic decrease, not necessarily exponential.

Common Pitfalls:
Confusing “capacity” with “area”; adding area can recover efficiency at higher total throughput.

Final Answer:
Decreases