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.Management Sciences
Category: Mechanical Operations
____________ mills fall in the category of tumbling mills ?
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A. Ball and pebble
B. Rod and tube
C. Compartment
D. All A., B. & C.
Pick out the wrong statement ?
A. Hammer crushers operate by impact action
B. Standard screens have circular opening
C. With increase in mesh number of screens, their diameter in microns decreases
D. 200 mesh screen has 200 openings per linear cm
Reduction ratio of crushers is the___________________?
A. Ratio of feed opening to discharge opening
B. Ratio of discharge opening to feed opening
C. Determining factor for minimum dia of the feed and the product
D. None of these
Grinding efficiency of a ball mill is of the order of _______________ percent?
A. 1-5
B. 40-50
C. 75-80
D. 90-95
To produce talcum powder, use_____________________?
A. Ball mill
B. Hammer mill
C. Jet mill
D. Pin mill
What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?
A. 16°
B. 32°
C. 40°
D. 46°
Pine oil used in froth floatation technique acts as a/an_____________________?
A. Collector
B. Modifier
C. Frother
D. Activator
Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are________________?
A. Carbonates
B. Sulphates
C. Silicates & phosphates
D. Bi-carbonates
For spheres, the specific surface shape factor is given by___________________?
A. AD/V
B. D/V
C. A/V
D. √(AD/V)
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