Commercial-scale sedimentation equipment\nSedimentation of slurries on a commercial scale is most commonly carried out in which device?

Introduction / Context:
Solid–liquid separations may be performed by gravitational settling (sedimentation) or by filtration. Large-volume clarification and concentration of slurries usually rely on sedimentation before polishing steps. Correctly identifying the principal equipment is vital for flowsheet development and cost estimates.

Given Data / Assumptions:

• “Commercial scale” implies large throughputs and continuous operation.
• Feed is a slurry of solids in liquid, needing thickening/clarification.

Concept / Approach:
Thickeners (circular or rectangular) provide a large cross-sectional area for gravity settling, with rake mechanisms to move settled solids to a discharge cone and overflow launders to collect clarified liquid. They are the standard for concentrating slurries and recovering process water. Classifiers provide size-based separation with settling but are not primarily used for bulk thickening of mixed fines; cyclones impart centrifugal force and are not sedimentation devices per se; rotary drum vacuum filters are filtration devices, not settling tanks; decanters rely on centrifugal settling in a rotating bowl rather than gravity alone.

Step-by-Step Solution:

Verification / Alternative check:
Mineral processing and wastewater plants standardize on high-rate/high-density thickeners for this service; filters are placed downstream if needed.

Why Other Options Are Wrong:

• Classifiers: size separation rather than bulk thickening.
• Vacuum filters: filtration, not sedimentation.
• Cyclones: centrifugal separation, not gravitational settling tanks.

Common Pitfalls:
Confusing clarification by sedimentation with dewatering by filtration; the former targets overflow clarity and underflow concentration via gravity.

Final Answer:
Thickeners