# Mechanical Operations Questions and Answers – Ball Mill

«
»

This set of Mechanical Operations Multiple Choice Questions & Answers (MCQs) focuses on “Ball Mill”.

1. What is the average particle size of ultra-fine grinders?
a) 1 to 20 µm
b) 4 to 10 µm
c) 5 to 200 µm
d) 50 to 100 µm

Explanation: The particle averaging 1 to 2 µm in size with substantially all particles through a standard 325 mesh screen.

2. Which of the following uses impact and attrition?
a) Ball mill
b) Tumbling mill
c) Ultra-fine grinders
d) Hammer mill

Explanation: Grinding takes place due to impact and attrition, it consists set of swing hammers, rotor, classifier wheels and fan wheels.

3. What is the feed size for a Ultra-Fine grinder?
a) > 34 inches
b) < 34 inches
c) > 12 inches
d) < 12 inches

Explanation: The feed size of ultra-fine grinder is less than 34 inches and the product sizes between 1 to 20 micro meter passing through 100 mesh.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

4. The fluid energy mill involves __________
a) Pressure
b) Temperature
c) Fluid
d) Density

Explanation: The fluid energy mill usually uses compressed air and super-heated steam admitted at a pressure of 7 atm through nozzles.

5. At what speed stirred mill operates?
a) 50 to 500 rpm
b) 5 to 10 rpm
c) 10 to 500 rpm
d) 100 to 1500 rpm

Explanation: In a stirred mill, a central paddle wheel or impellor armature stirs the media at speed from 100 to 1500 rpm.

6. What does colloid mill produces?
a) Emulsions and Solid dispersions
b) Wet and dry products
c) Coarse and fine particles

Explanation: Colloidal suspensions, emulsions and solid dispersions are produced by means of colloid mills or dispersions mills.

7. The clearance between rotor and stator is ______
a) 5 to 10 mm
b) 1 to 2.5 mm
c) 0 to 1.25 mm
d) 5 to 15 mm

Explanation: The mill consists of a flat rotor and stator, the clearance between the rotor and stator is generally 1 to 1.25 mm.

8. The power consumption of colloid mill is _______
a) Very low
b) Optimum
c) Critical
d) Very high

Explanation: The power consumption is very high and the material should therefore be ground as fine as possible before it is fed to mill.

9. The speed of a rotary knife cutter is ___
a) 100 to 500 rev/min
b) 200 to 900 rev/min
c) 400 to 600 rev/min
d) 50 to 60 rev/min

Explanation: A rotary knife cutter contains a horizontal rotor turning at 200 to 900 revolutions per minute, which is cylindrical chamber.

10. ______ indicates the impact of resistance.
a) Toughness
b) Rigidity
c) Brittleness
d) Fatigue

Explanation: Toughness indicates the impact of resistance. It is the inverse of friability and brittleness, it is also a deciding factor for commutation.

Sanfoundry Global Education & Learning Series – Mechanical Operations.

To practice all areas of Mechanical Operations, here is complete set of 1000+ Multiple Choice Questions and Answers.