Discussion
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- Question
In ball mill operation, the feed size (Df in meters) and the ball diameter (Db in metres) are related as ( where, K = grindability constant (varying from 0.9 to 1.4 in increasing order of hard ness))
Options- A. Db2 = K.Df
- B. Db = K.Df
- C. Db3 = K.Df
- D. Db2 = K.Df2
- Correct Answer
- Db2 = K.Df
- 1. __________ baffles are provided in ball mills.
Options- A. Horizontal
- B. No
- C. Only two
- D. None of these Discuss
- 2. Handling of ashes and similar materials can be done best by a __________ conveyor.
Options- A. flight
- B. drag or slat
- C. belt
- D. ribbon. Discuss
- 3. Which of the following must be stored in silos and not in open yard?
Options- A. Coke breeze
- B. High V.M. bituminous coal
- C. Sand
- D. None of these Discuss
- 4. The mechanism of size reduction by a hammer mill is by impact and attrition between the
Options- A. grinding element & the housing.
- B. feed particles.
- C. both (a) and (b).
- D. neither (a) nor (b). Discuss
- 5. Which of the following is not a wet classifier?
Options- A. Sharpies supercentrifuge
- B. Hydrocyclones
- C. Dorr Oliver rake classifier
- D. None of these Discuss
- 6. Grinding characteristic of a material is given by its
Options- A. HGI
- B. angle of repose
- C. shatter index
- D. abrasion index. Discuss
- 7. A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 ?m/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is
Options- A. 0.90 ?m/s
- B. 1 ?m/s
- C. 22.1 ?m/s
- D. 0.02 ?m/s Discuss
- 8. In froth floatation, chemical agent added to cause air adherence is called
Options- A. collector
- B. frother
- C. modifier
- D. activator Discuss
- 9. Velocity of a small particle of diameter 'Dp' at a distance 'r' from the rotational axis of a cyclone rotating at an angular speed '?' is given by (the other symbols are as per standard notation)
Options- A.
- B.
- C.
- D.
Discuss
- 10. __________ mills are termed as disintegrators.
Options- A. Cage
- B. Compartment
- C. Pebble
- D. All tumbling Discuss
Mechanical Operations problems
Search Results
Correct Answer: Horizontal
Correct Answer: drag or slat
Correct Answer: High V.M. bituminous coal
Correct Answer: both (a) and (b).
Correct Answer: None of these
Correct Answer: HGI
Correct Answer: 1 ?m/s
Correct Answer: collector
Correct Answer:
Correct Answer: Cage
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