Discussion
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- Question
Use of 'grinding aids' is done in __________ grinding.
Options- A. dry
- B. wet
- C. ultrafine
- D. intermediate
- Correct Answer
- dry
- 1. Which of the following is the hardest material?
Options- A. Calcite
- B. Quartz
- C. Corundum
- D. Gypsum Discuss
- 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
- 3. Gizzlies are used for separating __________ solids.
Options- A. coarse
- B. fine
- C. any size
- D. none of these Discuss
- 4. In case of a revolving mill, wet grinding compared to dry grinding
Options- A. requires more energy.
- B. has less capacity.
- C. complicates handling & classification of the product.
- D. none of these. Discuss
- 5. Rittinger's crushing law states that
Options- A. work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product.
- B. work required to form a particle of a particular size is proportional to the square root of the surface to volume ratio of the product.
- C. work required in crushing is proportional to the new surface created.
- D. for a given machine and feed, crushing efficiency is dependent on the size of the feed & product. Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. Sphericity of pulverised coal is
Options- A. 1
- B. <1
- C. >1
- D. ? Discuss
- 10. 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
Mechanical Operations problems
Search Results
Correct Answer: Corundum
Correct Answer: froth floatation
Correct Answer: fine
Correct Answer: none of these.
Correct Answer: work required in crushing is proportional to the new surface created.
Correct Answer:
Correct Answer: Po ? Re0.0
Correct Answer: both (a) & (b)
Correct Answer: <1
Correct Answer: d2
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