Engineering Questions with Answers - Multiple Choice Questions
Mechanical Operations MCQ’s – Ball Mill
1 - Question
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
View Answer
Answer: a
Explanation: The particle averaging 1 to 2 µm in size with substantially all particles through a standard 325 mesh screen.
2 - Question
Which of the following uses impact and attrition?
a) Ball mill
b) Tumbling mill
c) Ultra-fine grinders
d) Hammer mill
View Answer
Answer: c
Explanation: Grinding takes place due to impact and attrition, it consists set of swing hammers, rotor, classifier wheels and fan wheels.
3 - Question
What is the feed size for a Ultra-Fine grinder?
a) > 3⁄4 inches
b) < 3⁄4 inches
c) > 1⁄2 inches
d) < 1⁄2 inches
View Answer
Answer: b
Explanation: The feed size of ultra-fine grinder is less than 3⁄4 inches and the product sizes between 1 to 20 micro meter passing through 100 mesh.
4 - Question
The fluid energy mill involves __________
a) Pressure
b) Temperature
c) Fluid
d) Density
View Answer
Answer: a
Explanation: The fluid energy mill usually uses compressed air and super-heated steam admitted at a pressure of 7 atm through nozzles
5 - Question
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
View Answer
Answer: d
Explanation: In a stirred mill, a central paddle wheel or impellor armature stirs the media at speed from 100 to 1500 rpm.
6 - Question
What does colloid mill produces?
a) Emulsions and Solid dispersions
b) Wet and dry products
c) Coarse and fine particles
d) Broad particles
View Answer
Answer: a
Explanation: Colloidal suspensions, emulsions and solid dispersions are produced by means of colloid mills or dispersions mills.
7 - Question
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
View Answer
Answer: c
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 - Question
The power consumption of colloid mill is _______
a) Very low
b) Optimum
c) Critical
d) Very high
View Answer
Answer: d
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 - Question
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
View Answer
Answer: c
Explanation: A rotary knife cutter contains a horizontal rotor turning at 200 to 900 revolutions per minute, which is cylindrical chamber
10 - Question
______ indicates the impact of resistance.
a) Toughness
b) Rigidity
c) Brittleness
d) Fatigue
View Answer
Answer: a
Explanation: Toughness indicates the impact of resistance. It is the inverse of friability and brittleness, it is also a deciding factor for commutation.