Question 41 : The main size reduction operation in ultrafine grinders is
1. attrition
2. compression
3. cutting
4. impact
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Question 42 : Jigging is a technique by which different particles can be
1. separated by particle density.
2. separated by particle shape.
3. separated by particle size.
4. mixed
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Question 43 : Sulphuric acid mist is arrested by using a __________ scrubber.
1. packed wet
2. hollow wet
3. venturi
4. co-current
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Question 44 : Crushing of mineral particles is accomplished in a 'cage mill', when one or more alloy steel bars are revolved in opposite directions. It is a type of __________ mill.
1. impact
2. roll
3. none of these
4. vibratory
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Question 45 : Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
1. metalliferrous ores
2. non-metallic ores
3. asbestos & mica
4. basic slags
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Question 46 : The value of 'angle of nip' is generally about
1. 16°
2. 32°
3. 64°
4. 52°
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Question 47 : Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is
1. 0.1 to 0.3
2. 0.01 to 0.1
3. 0.2 to 0.4
4. 0.2 to 0.8
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Question 48 : Highly viscous liquids & pastes are agitated by
1. propellers
2. none of these
3. turbine agitators
4. multiple blade paddles
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Question 49 : Pick out the correct statement:
1. The operating cost of shaking screen is more than that of a vibrating screen.
2. Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products.
3. Screen capacity does not depend upon the specific gravity of the minerals.
4. Asphalt is best crushed using toothed roll crusher.
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Question 50 : Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?
1. Spiral separator
2. Trough washer
3. Froth floatation
4. Baum jig washer
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