PolyLearning

16. Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle).
a. A
b. B
c. C
d. D
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Answer: (a).A

17. What is the reduction ratio in a fine crushing operation having following feed and product sizes?
a. 0.5
b. 2
c. 5
d. 10
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Answer: (b).2

18. The value of 'angle of nip' is generally about
a. 16°
b. 32°
c. 52°
d. 64°
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Answer: (b).32°

19. Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
a. metalliferrous ores
b. non-metallic ores
c. basic slags
d. asbestos & mica
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Answer: (a).metalliferrous ores

20. Sulphuric acid mist is arrested by using a __________ scrubber.
a. packed wet
b. hollow wet
c. venturi
d. co-current
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Answer: (c).venturi

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