Mechanical Operations

301. The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size to 50 μm is

1. 6.35 kWh/ton
2. 9.0 kWh/ton
3. 18 kWh/ton
4. 25.4 kWh/ton

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302. The equivalent diameter of channel of a constant non-circular cross-section of 3 cm by 6 cm will be _________ cms.

1. 20
2. 12
3. 8
4. 2

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303. The filtrate flow rate in constant pressure filtration

1. Continuously increases
2. Continuously decreases
3. Remain constant throughout
4. May increase or decrease; depends on the pressure

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304. The grinding in a hammer crusher takes place due to the

1. Attrition
2. Impact
3. Both (A) & (B)
4. Neither (A) nor (B)

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305. The inlet pressure in a constant rate filtration

1. Increases continuously
2. Decreases gradually
3. Remains constant
4. None of these

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306. The main differentiation factor between tube mill and ball mill is the

1. Length to diameter ratio
2. Size of the grinding media
3. Final product size
4. Operating speed

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307. The main size reduction operation in ultrafine grinders is

1. Cutting
2. Attrition
3. Compression
4. Impact

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308. The material is crushed in a gyratory crusher by the action of

1. Impact
2. Compression
3. Attrition
4. Cutting

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309. The maximum slope of a belt conveyor can be

1. 15°
2. 30°
3. 45°
4. 60°

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310. The mechanism of size reduction by a hammer mill is by impact and attrition between the

1. Grinding element & the housing
2. Feed particles
3. Both (A) and (B)
4. Neither (A) nor (B)

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