Primary function of cyclones:\nIndustrial cyclones are used primarily for the separation of which phases?

Introduction / Context:
Hydrocyclones and gas cyclones exploit centrifugal fields to effect density-based separation. Recognising what phases they best separate is foundational for selecting them in dust collection, product recovery, dewatering, and classification circuits.

Given Data / Assumptions:

• “Cyclone” includes gas cyclones (for dust) and hydrocyclones (for slurries).
• Operation involves swirling flow producing radial acceleration.

Concept / Approach:
In both gas and liquid service, cyclones separate dispersed solid particles from a continuous fluid phase by imparting centripetal acceleration, forcing denser solids to migrate outward for collection while clean fluid exits centrally. They are not commonly used to separate liquid–liquid pairs (though specialty designs exist), nor to sort gas species of nearly equal density. Solid–solid separation is indirect—via classification in a suspending fluid—not by directly processing two solid streams.

Step-by-Step Solution:

Verification / Alternative check:
Plant P&IDs show gas cyclones upstream of baghouses and hydrocyclones in grinding circuits to classify solids from slurry—both aligning with solids-from-fluids duty.

Why Other Options Are Wrong:

• “Solids” alone is incomplete.
• Liquids only/gases from gases: not typical cyclone duty.
• Solids from solids: requires a fluidising medium; the cyclone acts on a slurry or gas-solid stream, not two solid feeds.

Common Pitfalls:
Expecting submicron capture with gas cyclones; their efficiency drops for very fine particles without preconditioning or multicyclones.

Final Answer:
Solids from fluids (gas or liquid)