Mechanical Operations MCQs

Question 1

Fluid energy mill comes in the category of

Accepted Answer

Ultrafine grinder

Answer

Grinder

Answer

Crusher

Answer

Cutter

Question 2

For efficient grinding, ball mills must be operated

Accepted Answer

At a speed less than the critical speed

Answer

At a speed more than the critical speed

Answer

At a speed equal to the critical speed

Answer

With minimum possible small balls

Question 3

Use of baffles in agitators help in minimising the __________ tendency.

Accepted Answer

Both A & B

Answer

Swirling

Answer

Vortexing

Answer

Neither A nor B

Question 4

Cyclones are used primarily for separating

Accepted Answer

Solids from fluids

Answer

Solids

Answer

Liquids

Answer

Solids from solids

Question 5

With increase in the capacity of screens, the screen effectiveness

Accepted Answer

Decreases

Answer

Remains unchanged

Answer

Increases

Answer

Decreases exponentially

Question 6

Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?

Accepted Answer

Rittinger's law

Answer

Bond's crushing law

Answer

Kick's law

Answer

None of these

Question 7

Bond crushing law

Accepted Answer

Calls for relatively less energy for the smaller product particles, than does the Rittinger law

Answer

Is less realistic in estimating the power requirements of commercial crushers

Answer

States that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product

Answer

States that the work required for the crushing is proportional to the new surface created

Question 8

Energy consumed for crushing one ton of material ranges from __________ kWh.

Accepted Answer

0.5 to 1.5

Answer

0.01 to 0.1

Answer

2 to 3.5

Answer

4 to 5

Question 9

The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)

Accepted Answer

Independent of ΔP

Answer

$$ \propto \Delta {	ext{P}}$$

Answer

$$ \propto \frac{1}{{\Delta {	ext{P}}}}$$

Answer

$$ \propto \sqrt {\Delta {	ext{P}}} $$