Mechanical Operations problems
- 1. Gizzlies are used for separating __________ solids.
Options- A. coarse
- B. fine
- C. any size
- D. none of these Discuss
Correct Answer: fine
- 2. There is practically no alternative/competitor to __________ in the beneficiation treatment of sulphide ores.
Options- A. classification
- B. tabling
- C. jigging
- D. froth floatation Discuss
Correct Answer: froth floatation
- 3. Which of the following is the hardest material?
Options- A. Calcite
- B. Quartz
- C. Corundum
- D. Gypsum Discuss
Correct Answer: Corundum
- 4. Use of 'grinding aids' is done in __________ grinding.
Options- A. dry
- B. wet
- C. ultrafine
- D. intermediate Discuss
Correct Answer: dry
- 5. Critical Speed (Nc) of a ball mill is given by(where R1 and R2 are radii of ball mill and the ball respectively).
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 6. At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied:
Po = ?/?N3 D5 : Power number
Re = ? N D2/?: Reynold's number
N is the impeller rotational speed, and D is the impeller diameter.
Options- A. Po ? Re-1.0
- B. Po ? Re0.0
- C. Po ? Re0.5
- D. Po ? Re1.0 Discuss
Correct Answer: Po ? Re0.0
- 7. The important dimensional group involved in the power requirement calculation in mixing operation is the __________ number.
Options- A. Reynold's
- B. Froude
- C. both (a) & (b)
- D. neither (a) nor (b) Discuss
Correct Answer: both (a) & (b)
- 8. Sphericity of pulverised coal is
Options- A. 1
- B. <1
- C. >1
- D. ? Discuss
Correct Answer: <1
- 9. For a sphere falling in the constant drag co-efficient regime, its terminal velocity depends on its diameter (d) as
Options- A. d
- B. d
- C. d2
- D. 1/d Discuss
Correct Answer: d2
- 10. For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is
Options- A. 2250
- B. 1125
- C. 460
- D. 230 Discuss
Correct Answer: 230
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