Screens and crushers: Identify the correct statement regarding mineral processing operations and equipment selection.

Introduction / Context:
Mineral processing involves crushing, screening, and separation steps. Equipment choice impacts product quality, energy use, and downstream performance. Understanding which assertions are accurate helps avoid common plant design mistakes.

Given Data / Assumptions:

• Typical ceramics require high whiteness and purity.
• Screens can be vibrating or shaking (reciprocating) with different costs and efficiencies.
• Crusher selection depends on material hardness, stickiness, and abrasiveness.

Concept / Approach:
Iron contamination (from tramp iron or iron-bearing minerals) causes ceramic discoloration upon firing. Magnetic separation removes iron-bearing particles, protecting product whiteness. Vibrating screens generally offer higher capacity and lower maintenance than shaking screens. Screen capacity is affected by bulk density/specific gravity. Toothed roll crushers are better for friable, moderately soft materials (e.g., coal, salt) rather than sticky asphalt.

Step-by-Step Solution:
Evaluate Option A: Correct—magnetic separation removes iron that would stain ceramics.Option B: Incorrect—shaking screens tend to have higher operating cost than vibrating screens.Option C: Incorrect—capacity depends on material properties including bulk density.Option D: Dubious—sticky asphalt tends to smear; toothed rolls are not ideal.

Verification / Alternative check:
Ceramics processing references specify magnetic removal to achieve white bodies. Screen manufacturer data show capacity and cost advantages of vibrating designs.

Why Other Options Are Wrong:

• B: Reverses the usual cost relation.
• C: Ignores role of bulk density on bed depth and screening rate.
• D & E: Mis-match crusher type to sticky feeds; asphalt requires specialized handling.

Common Pitfalls:
Assuming one crusher fits all; not accounting for stickiness leading to plugging and smearing.

Final Answer:
Removing iron from ceramic feed by magnetic separation prevents discoloration of ceramic products