Question

Which of the following mills is based on the mechanism of impact and attrition for size reduction:

• A. Roller mill
• B. Fluid energy mill
• C. Hammer mill
• D. Colloid mill

Answer 1

The Correct Option is B

The fluid energy mill (also known as a jet mill) operates on the principle of impact and attrition for size reduction. This type of mill uses high-velocity air or gas jets to cause particles to collide with one another at high speeds, resulting in the fragmentation of the particles. The primary mechanism involves both impact (particles striking each other at high velocity) and attrition (particles grinding against each other), making it effective for fine size reduction, especially for materials that require micronization.
The other mills listed have different operating mechanisms:
 - Roller mills typically rely on compression and shear forces to break down materials. 
- Hammer mills use impact forces primarily but often work with larger particle sizes and less fine grinding. 
- Colloid mills primarily use shearing and grinding forces for producing emulsions and suspensions, but not specifically impact and attrition. 
Thus, the correct answer is B, as the fluid energy mill is based on the mechanism of impact and attrition for size reduction.