Mechanical Operations problems
- 1. A fluid energy mill is used for
Options- A. cutting
- B. grinding
- C. ultra grinding
- D. crushing Discuss
Correct Answer: ultra grinding
- 2. Which of the following is the softest material?
Options- A. Talc
- B. Feldspar
- C. Corundum
- D. Calcite Discuss
Correct Answer: Talc
- 3. Filtration rate through a filter cake is proportional to (where, S = filtering surface R = specific cake resistance ? = viscosity of the filtrate)
Options- A. S
- B. 1/R
- C. 1/?
- D. all (a), (b) & (c) Discuss
Correct Answer: all (a), (b) & (c)
- 4. Optimum ratio of operating speed to critical speed of a trommel is
Options- A. 0.33-0.45
- B. 1.33-1.45
- C. 0.5-2
- D. 1.5-2.5 Discuss
Correct Answer: 0.33-0.45
- 5. Solid particles of different densities are separated by
Options- A. filters
- B. thickness
- C. cyclones
- D. sorting classifier Discuss
Correct Answer: sorting classifier
- 6. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ?L) located at a radial distance R from the axis of rotation. The thickness of the liquid film is ? and no cake is formed. The initial pressure drop during filtration is
Options- A. ½w2 . R2 . ?L
- B. ½w2 . ?2 . ?L
- C. ½w2 . ??L (2R + ?)
- D. ½w2 . R . ?L(R + 2?) Discuss
Correct Answer: ½w2 . ??L (2R + ?)
- 7. Dry powdery solid materials are transported by a __________ conveyor.
Options- A. belt
- B. bucket
- C. screw
- D. none of these Discuss
Correct Answer: screw
- 8. In a roll crusher, both the rolls
Options- A. have the same diameter.
- B. are rotated towards each other.
- C. run either at the same or different speeds.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
- 9. What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls?
Options- A. 0.5
- B. 1.0
- C. 2.76
- D. 0.66 Discuss
Correct Answer: 0.66
- 10. The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant __________ filtration.
Options- A. rate
- B. pressure
- C. both (a) & (b)
- D. neither (a) nor (b) Discuss
Correct Answer: both (a) & (b)
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