Mechanical Operations

211. Moore filter is a _________ filter.

1. Leaf
2. Press
3. Rotary
4. Sand

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212. Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, V_p = volume of one particle, ρ= density of particles)

1. m/ρ . V_p
2. m . ρ/V_p
3. m . V_p/ρ
4. V_p/m . ρ

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213. Optimum ratio of operating speed to critical speed of a trommel is

1. 0.33-0.45
2. 1.33-1.45
3. 0.5-2
4. 1.5-2.5

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214. Ore concentration by jigging is based on the difference in the _________ of the particles.

1. Specific gravities
2. Wettability
3. Shape
4. None of these

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215. Out of the following size reduction equipments, the maximum feed size can be accepted by the

1. Tube mill
2. Ball mill
3. Jaw crusher
4. Jet pulveriser

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216. PaD⁵le agitator

1. Is suitable for mixing low viscosity liquids
2. Produces axial flow
3. Moves at very high speed
4. None of these

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217. Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is _________ microns.

1. < 5
2. 10 to 25
3. < 74
4. > 1000

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218. 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

1. Bronze
2. Stainless steel
3. Flint or porcelain
4. Concrete

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219. Percentage of drum submerged in the slurry in case of rotary drum filter is

1. 3
2. 30
3. 85
4. 25

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220. Pick out the correct statement.

1. The capacity and the effectiveness of a screen are the same
2. The capacity and the effectiveness of screen are opposing factors
3. The screening surface of a 'reel' (a revolving screen used in flour mills) is made of silk bolting cloth supported by wire mesh
4. Both (B) and (C)

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