In mineral processing and metallurgical operations, which unit operation is referred to as “comminution” (i.e., the deliberate size reduction of ore into finer particles prior to separation)?

Introduction:
“Comminution” is the fundamental first step in most mineral dressing flowsheets. It refers to reducing run-of-mine rock to smaller, more liberatable sizes so that valuable minerals can be economically separated from gangue in later stages. This question checks whether you can distinguish comminution from downstream concentration methods such as panning, spiralling, and tabling.

Given Data / Assumptions:

• Context is mineral dressing (mineral processing).
• Comminution means mechanical size reduction.
• Panning, spiralling, and tabling are gravity separation methods, not size reduction steps.

Concept / Approach:
Comminution is carried out by crushing (jaw, gyratory, cone crushers) and grinding (rod, ball, SAG, and AG mills). Its goals include liberation of valuable minerals, preparing feed for classification, and controlling surface area for subsequent leaching or flotation. Gravity devices (pans, spirals, tables) classify or separate particles by density/shape after comminution and classification, not before.

Step-by-Step Solution:
Identify what comminution means: deliberate size reduction.List examples: crushing and grinding equipment.Recognize each option: panning, spiralling, tabling are gravity concentration methods.Therefore none of the listed devices performs comminution.

Verification / Alternative check:
Standard flowsheets show crushing and grinding before gravity concentration or flotation. No reputable text classifies panning/spiralling/tabling as comminution operations.

Why Other Options Are Wrong:

• Panning: density-based gold recovery; no size reduction.
• Spiralling: separates by density and hydrodynamics; no breakage.
• Tabling: uses differential motion on a riffled deck; again, separation not size reduction.

Common Pitfalls:
Assuming any early-stage unit is “comminution.” Only machines that break particles (crushers, mills) qualify. Gravity tools handle already ground material.

Final Answer:
None of these