Engineering Questions with Answers - Multiple Choice Questions

# Mechanical Operations MCQ’s – Action of Tumbling Mill

1 - Question

Which of the following is a standard screen?
a) Treybal screen
b) Tyler screen
c) McCabe screen
d) Camp screen

Explanation: One of the most common set of screens is the Tyler screens, this is based on the 200 mesh screen with wire 0.021 inch.

2 - Question

Two successive screens have a ratio of
a) 1:2
b) 1: √2
c) 1: √3
d) 2:3

Explanation: The mesh is so adjusted that the size of opening in one screen is approximately twice the area of the opening i.e. that ratio of 1:√2.

3 - Question

The efficiency of the ideal screens are ___
a) Unity
b) Infinity
c) Zero
d) Can’t be determined

Explanation: The effectiveness of the ideal screen is unity, these screens are not found in practice as they are totally imaginary.

4 - Question

Efficiency of actual screens is always _____
a) > 1
b) < 1
c) = 1
d) = 0

Explanation: The effectiveness of the actual screen is always less than one, all screens available in the market are the actual screens.

5 - Question

Which of the following involves vibrations?
a) Ball mill
b) Roll mill
c) Grizzly screen
d) Hammer mill

Explanation: Vibrating grizzlies are simply mounted on eccentrics so that entire assembly is given a back and forth movement or a positive circle throw

6 - Question

What is the angle of inclination of a gyrating screen?
a) 16 to 30
b) 15 to 20
c) 45 to 60
d) 60 to 90

Explanation: The casing is inclined at an angle between 160 and 300 with the horizontal, the gyration while takes place vertical along the horizontal.

7 - Question

____ should be the motor power for a standard gyrator.
a) 5 to 10 hp
b) 1 to 3 hp
c) 6 to 8 hp
d) 10 to 20 hp

Explanation: One particular combination of feed generally gives maximum yield of the product that is 1 to 3 hp of motor power and 600 to 1800 r/min.

8 - Question

Which of the following operates on the slowest speed?
a) Gyrating screens
b) Tromells
c) Tumbler
d) Oscillating screen

Explanation: These are characterized by low speed i.e. 300 to 400 rpm oscillation in a plane essentially parallel to the screen cloth.

9 - Question

All wet classifiers depend upon the difference in settling velocity of particles.
a) True
b) False

Explanation: All wet classifiers depend upon settling rate between coarse and fine or heavy or light gravity particles in the pool confined or a tank.

10 - Question

The particles which passes through a particular mesh size is called as ____
a) Oversized
b) Undersized
c) Exact
d) By-pass