Separations by inertia vs gravity In which of the following units is gravity settling <em>not</em> the operative separation mechanism?

Introduction / Context:
Particle–fluid separators rely on different forces: gravity, centrifugal, and sometimes interfacial forces. Correctly identifying the dominant mechanism helps select and size equipment for slurry classification and thickening.

Given Data / Assumptions:

• Hydrocyclone imposes strong swirling flow field.
• Classifiers and thickeners operate under Earth gravity.
• Feed is a solid–liquid slurry.

Concept / Approach:
Hydrocyclones separate based on centrifugal acceleration (often tens to hundreds of g), vastly exceeding normal gravity and enabling sharp classification at small sizes. Dorr-thickeners, sedimentation tanks, and many classifiers rely on gravitational settling and hindered settling behavior.

Step-by-Step Solution:

Verification / Alternative check:
Cut size correlations in hydrocyclones use swirl intensity and pressure drop (centrifugal field), unlike settling basin design using Stoke’s law under 1 g.

Why Other Options Are Wrong:

• Classifier, Dorr-thickener, Sedimentation tank: All depend on gravity-driven settling and clarification.

Common Pitfalls:
Assuming hydrocyclones can handle very high solids without roping; stable operation requires proper pressure and underflow/overflow control.

Final Answer:
hydrocyclone