Name the revolving grinding mill that is internally divided by perforated partitions into multiple sections so that preliminary grinding occurs in the feed-end compartment and finishing grinding occurs at the discharge end.

Introduction / Context:
Some tumbling mills are segmented internally to stage the grinding duty. The front section handles coarser breakage with larger media; the downstream section finishes the grind with smaller media. This configuration appears frequently in cement and mineral circuits.

Given Data / Assumptions:

• Mill is divided by perforated partitions/diaphragms.
• Coarse feed enters the first compartment; finer material progresses to the second.
• Perforations allow passage of sized material while retaining coarse load and media.

Concept / Approach:
The standard term for such a mill is “compartment mill.” Tube mill refers to long L/D geometry, rod and pebble refer to media type rather than internal partitioning.

Step-by-Step Solution:
Map the description (perforated partitions, staged grinding) to standard nomenclature.Identify “compartment mill” as the correct industry term.

Verification / Alternative check:
Process diagrams and OEM brochures describe two-compartment finish mills with diaphragms and intermediate scoops as compartment mills.

Why Other Options Are Wrong:
Tube mill: long shell but not necessarily partitioned.Rod/pebble mills: distinguished by media, not by compartments.

Common Pitfalls:
Assuming all long mills are “tube mills”; the defining feature here is the internal compartmentation, not just the L/D ratio.

Final Answer:
Compartment mill