Identify the mill that is NOT a revolving (tumbling) mill used for grinding by cascading media.

Introduction / Context:
Revolving or tumbling mills (ball, pebble, rod, tube, compartment) grind by cascading and cataracting media in a rotating cylindrical shell. Impact mills such as cage mills operate on a different principle.

Given Data / Assumptions:

• Pebble, tube, and compartment mills are ball/pebble variants.
• Cage mill consists of counter-rotating cages; the shell itself does not tumble media.

Concept / Approach:
Distinguish media-tumbling action from high-speed impact within stationary housings. Tumbling mills rotate a cylinder partially filled with media; cage mills accelerate particles through bars for impact and shattering, not tumbling.

Step-by-Step Solution:
Classify each option by grinding mechanism.Identify the outlier (impact-type, not tumbling): cage mill.

Final Answer:
Cage mill