Mechanical Operations

311. The most common filter aid is

1. Diatomaceous earth
2. Calcium silicate
3. Sodium carbonate
4. Silica gel

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312. The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the

1. Venturi atomiser
2. Gravity settling chamber
3. Electro-static precipitator
4. Cyclone separator

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313. The most suitable equipment for removing the fine dust particle (< 1 micron dia.) from air below its dew point will be a/an

1. Bag filter
2. Electrostatic precipitator
3. Cyclone separator
4. Wet scrubber

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314. The most suitable equipment for the transportation of 200 mesh size particles is a

1. Bucket elevator
2. Pneumatic conveyor
3. Screw conveyor
4. Belt conveyor

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315. The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a

1. Boundary mixer
2. Propeller agitator
3. Sharpies centrifuge
4. None of these

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316. The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the _________ filter.

1. Vacuum
2. Sand
3. Plate & frame
4. Rotary

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317. The opening of a 200 mesh screen (Taylor series) is

1. 0.0074 cm
2. 0.0074 mm
3. 0.0047 cm
4. 74 milli-microns

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318. The operating speed of a ball mill should be _________ the critical speed.

1. Less than
2. Much more than
3. At least equal to
4. Slightly more than

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319. The optimum moisture content in solids to be crushed/ground ranges from _________ percent.

1. 3 to 4
2. 8 to 10
3. 10 to 15
4. 15 to 20

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320. The porosity of a compressible cake is

1. Minimum at the filter medium
2. Minimum at the upstream face
3. Maximum at the filter medium
4. Same throughout the thickness of cake

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