Question

Which mill is most suitable for grinding hard and abrasive materials?

• A. Hammer mill
• B. Ball mill
• C. Roller mill
• D. Cutter mill

Hint:

Ball mill reduces size by impact and attrition, making it suitable for hard and abrasive materials.

Answer 1

The Correct Option is B

Concept:
Milling is a size reduction process used to reduce large particles into smaller particles. Different mills are selected depending on the nature of the material.

Step 1: Understanding hard and abrasive materials.
Hard materials require strong grinding force. Abrasive materials may damage equipment surfaces, so the mill should be suitable for repeated impact and attrition.

Step 2: Working of ball mill.
A ball mill contains balls inside a rotating cylinder. As the cylinder rotates, the balls fall on the material and produce size reduction by:
• Impact
• Attrition

Step 3: Why ball mill is suitable.
Ball mills are commonly used for grinding hard and abrasive materials because the grinding media can apply strong mechanical force and produce fine powder.

Step 4: Checking other mills.
Hammer mill is useful for brittle materials but is not the best for hard abrasive materials.
Roller mill is more suitable for compression and soft to moderately hard materials.
Cutter mill is mainly used for fibrous and tough materials, not hard abrasive materials.

Step 5: Final answer.
Therefore, the most suitable mill for hard and abrasive materials is Ball mill. \[ \boxed{\text{Ball mill}} \]