Question

Major force of action in case of Rietz mill is

• A. Crushing
• B. Impact
• C. Shear
• D. Cutting

Hint:

Mechanisms of size reduction:
Hammer mill Rietz mill $\rightarrow$ Impact
Roller mill $\rightarrow$ Compression Crushing
Burr mill Attrition mill $\rightarrow$ Shear Attrition
Rotary knife cutter $\rightarrow$ Cutting.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Size reduction mills apply mechanical forces including compression/crushing, impact, attrition/shear, and cutting to disintegrate solid foods and agricultural materials.

Step 2: Detailed Explanation:
A Rietz disintegrator Rietz mill is an industrial high-speed hammer-type disintegrator featuring a rotor with rotating heavy rigid hammers enclosed inside a 360-degree cylindrical screen.
Material entering the feed hopper is struck by high-velocity rotating hammer tips.
The primary mechanism of size reduction is Impact force (coupled with secondary attrition against the sizing screen).

Step 3: Final Answer:
Thus, the major force of action in a Rietz mill is Impact, matching option (B).