Exp 3 (2)

Question 1

What is the importance of rotational speed in mill operation?

Answer 1

Proper and efficient mill operation

Rotational speed affects energy imparted on the product and media movement.

Question 2

What happens if the rotational speed is too low?

Answer 2

Little energy is imparted on the product

Low speed results in ineffective milling.

Question 3

What is cataracting in the context of mill operation?

Answer 3

Inefficient media movement generating high impact

Cataracting occurs when the speed is too fast.

Question 4

What is the consequence of a speed that is too fast in a mill?

Answer 4

Increased mill wear and media centrifuging

Centrifuging leads to virtually no milling or movement.

Question 5

What is the ideal mill speed as a percentage of critical speed?

Answer 5

55% to 75% of critical speed

This range optimizes milling efficiency.

Question 6

Fill in the blank: The ideal mill speed is usually between ______ and ______ of critical speed.

Answer 6

55%, 75%

This ensures effective milling without excessive wear.

Question 7

What is the relationship between rotational speed and milling effectiveness?

Answer 7

Rotational speed affects the energy imparted and media behavior

Optimal speed ensures effective milling while minimizing wear.

Question 8

What are the variables involved in calculating critical speed in a ball mill?

Answer 8

g (acceleration due to gravity), R (radius of ball mill), r (radius of ceramic ball)

g = 9.8 m/s², R in cm, r in mm.