Mechanical Operations problems
- 1. Production rate __________ with increased fineness, with a given energy input to the size reduction machine.
Options- A. decreases
- B. increases
- C. remains unchanged
- D. may increase or decrease; depends on the machine Discuss
Correct Answer: decreases
- 2. The unit of specific cake resistance is
Options- A. gm/cm2
- B. cm/gm
- C. cm/gm2
- D. gm/gm Discuss
Correct Answer: gm/cm2
- 3. Ultra centrifuges are used for the separation of __________ solid particles.
Options- A. coarse
- B. fine
- C. colloidal
- D. dissolved Discuss
Correct Answer: colloidal
- 4. According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively).
Options- A. (S/V)p
- B. (S/V)p
- C. (S/V)2p
- D. (S/V)f Discuss
Correct Answer: (S/V)p
- 5. Gold ore concentration is mostly done using
Options- A. jigging
- B. tabling
- C. froth floatation
- D. elutriation Discuss
Correct Answer: tabling
- 6. Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm.
Options- A. 0.007
- B. 0.30
- C. 50
- D. 0.014 Discuss
Correct Answer: 0.30
- 7. Out of the following size reduction equipments, the maximum feed size can be accepted by the
Options- A. tube mill
- B. ball mill
- C. jaw crusher
- D. jet pulveriser Discuss
Correct Answer: jaw crusher
- 8. Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity?
Options- A. Sphere
- B. Cube
- C. Cylinder (L/D = 1)
- D. Raschig rings Discuss
Correct Answer: Sphere
- 9. Electrical energy consumed by a jaw crusher is not a function of the
Options- A. average feed size
- B. average product size
- C. machine capacity
- D. none of these Discuss
Correct Answer: none of these
- 10. Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately?
Options- A. Rittinger's law
- B. Kick's law
- C. Bond's law
- D. none of these Discuss
Correct Answer: Rittinger's law
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