Chemical Engineering - Mechanical Operations

36. 

The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size to 50 μrn is

A. 6.35 kWh/ton
B. 9.0 kWh/ton
C. 18 kWh/ton
D. 25.4 kWh/ton

Answer: Option C

Explanation:

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37. 

Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?

A. Trough washer
B. Baum jig washer
C. Spiral separator
D. Froth floatation

Answer: Option D

Explanation:

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38. 

Pick out the correct statement:

A. Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products.
B. The operating cost of shaking screen is more than that of a vibrating screen.
C. Screen capacity does not depend upon the specific gravity of the minerals.
D. Asphalt is best crushed using toothed roll crusher.

Answer: Option A

Explanation:

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39. 

Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is

A. 0.01 to 0.1
B. 0.1 to 0.3
C. 0.2 to 0.8
D. 0.2 to 0.4

Answer: Option C

Explanation:

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40. 

Highly viscous liquids & pastes are agitated by

A. propellers
B. turbine agitators
C. multiple blade paddles
D. none of these

Answer: Option C

Explanation:

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