Mechanical Operations problems
- 1. Size reduction of __________ is accomplished in steam heated rollers and roll crushers.
Options- A. resins
- B. gums
- C. hard rubber
- D. waxes Discuss
Correct Answer: hard rubber
- 2. For a non-spherical particle, the sphericity
Options- A. is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
- B. has the dimension of length.
- C. is always less than 1.
- D. is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle. Discuss
Correct Answer: is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
- 3. Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of
Options- A. bronze
- B. stainless steel
- C. flint or porcelain
- D. concrete Discuss
Correct Answer: flint or porcelain
- 4. In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the
Options- A. square root of the velocity.
- B. square of the viscosity.
- C. filtration time only.
- D. washing time only. Discuss
Correct Answer: square root of the velocity.
- 5. Pick out the correct statement:
Options- A. Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products.
- B. The operating cost of shaking screen is more than that of a vibrating screen.
- C. Screen capacity does not depend upon the specific gravity of the minerals.
- D. Asphalt is best crushed using toothed roll crusher. Discuss
Correct Answer: Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products.
- 6. Froth floatation is the most suitable for treating
Options- A. iron ores
- B. sulphide ores
- C. quartzite
- D. none of these Discuss
Correct Answer: sulphide ores
- 7. Balls for ball mills are never made of
Options- A. forged/cast steel
- B. lead
- C. cast iron
- D. alloy steel Discuss
Correct Answer: lead
- 8. Which of the following is not categorised as a "mechanical operation"?
Options- A. Agitation
- B. Filtration
- C. Size enlargement
- D. Humidification Discuss
Correct Answer: Humidification
- 9. In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
Options- A. 4
- B. 1/4
- C. 1
- D. 1/2 Discuss
Correct Answer: 1/4
- 10. In case of a hammer crusher,
Options- A. crushing takes place by impact breaking.
- B. maximum acceptable feed size is 30 cms.
- C. reduction ratio can be varied by adjusting the distance from cage to hammers.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
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