Separation of solid particles primarily by density differences (at similar sizes) is carried out by which device?

Introduction / Context:
While many classifiers separate by size via settling velocity, some units exploit density differences to a greater extent, especially at overlapping sizes.

Concept / Approach:
Sorting or hydraulic classifiers stratify particles in a rising or falling fluid so that higher-density particles settle differently than lighter ones. Cyclones primarily classify by size (though density has an effect); filters and thickeners remove solids by phase separation or concentration, not by density discrimination at similar sizes.

Final Answer:
Sorting (hydraulic) classifier