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- Question
Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed?
Options- A. Wet grinding in low viscous suspension.
- B. Wet grinding in high viscous suspension.
- C. Dry grinding of large particles (upto 1.25 cms).
- D. Dry grindng of large particles in un-baffed mills.
- Correct Answer
- Dry grindng of large particles in un-baffed mills.
- 1. During filtration operation, the filtrate encounters the resistance of the
Options- A. filter medium.
- B. cake.
- C. channel carrying the slurry to the upstream side of the cake and filtrate away from the filter medium.
- D. all (a), (b) and (c) Discuss
- 2. The filtrate flow rate in constant pressure filtration
Options- A. continuously increases.
- B. continuously decreases.
- C. remains constant throughout.
- D. may increase or decrease ; depends on the pressure. Discuss
- 3. Pick out the wrong statement.
Options- A. Hammer crushers operate by impact action.
- B. Standard screens have circular opening.
- C. With increase in mesh number of screens, their diameter in microns decreases.
- D. 200 mesh screen has 200 openings per linear cm. Discuss
- 4. Mixing mechanism employed in a pan mixer is by
Options- A. mulling
- B. kneading
- C. dispersion
- D. none of these Discuss
- 5. Stamp mills are generally used for crushing
Options- A. iron ores
- B. gold ores
- C. talc
- D. diamond Discuss
- 6. Sphericity of raschig ring (whose length and diameter are equal) is
Options- A. >1
- B. <1
- C. 1
- D. 2 Discuss
- 7. With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge
Options- A. increases
- B. decreases
- C. remains constant
- D. increases linearly Discuss
- 8. Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.
Options- A. < 5
- B. 10 to 25
- C. < 74
- D. > 1000 Discuss
- 9. The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the
Options- A. venturi atomiser
- B. gravity settling chamber
- C. electro-static precipitator
- D. cyclone separator Discuss
- 10. Xanthates are used in the froth floatation process as a/an
Options- A. conditioner
- B. frother
- C. collector
- D. activator Discuss
Mechanical Operations problems
Search Results
Correct Answer: all (a), (b) and (c)
Correct Answer: continuously decreases.
Correct Answer: 200 mesh screen has 200 openings per linear cm.
Correct Answer: mulling
Correct Answer: gold ores
Correct Answer: 1
Correct Answer: increases
Correct Answer: < 74
Correct Answer: electro-static precipitator
Correct Answer: collector
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