Mechanical Operations

21. _________ mills are termed as impactors.

1. Hammer
2. Cage
3. Rolling-compression
4. None of these

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22. _________ mills fall in the category of tumbling mills,

1. Ball and pebble
2. Rod and tube
3. Compartment
4. All (A), (B) & (C)

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23. _________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution.

1. Tumbler
2. Banbury
3. Muller
4. Ribbon blender

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24. 200 mesh screen means 200 openings per

1. cm₂
2. cm
3. inch
4. inch2

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25. 200 mesh sieve size corresponds to _________ microns.

1. 24
2. 74
3. 154
4. 200

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26. A _________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream.

1. Thickener
2. Classifier
3. Strainer
4. Clarifier

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27. A _________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end.

1. Compartment
2. Tube
3. Rod
4. Pebble

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28. A _________ mixer resembles a ball mill without balls.

1. Banbury
2. Pug mill
3. Tumbling
4. Pan

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29. A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 μm/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is

1. 0.90 μm/s
2. 1 μm/s
3. 22.1 μm/s
4. 0.02 μm/s

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30. A belt conveyor used for the transportation of materials can

1. Run upto 1 km
2. Travel at a speed upto 300 metres/minute
3. Handle materials upto 5000 tons/hr
4. All (A), (B) and (C)

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