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.Management Sciences
Category: Mechanical Operations
Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for__________________?
A. British standard screens
B. German standard screens (DIN 1171) etc
C. American standard screens (ASTM and Tyler standard screens)
D. All A., B. and C.
In a roll crusher, both the rolls_________________?
A. Have the same diameter
B. Are rotated towards each other
C. Run either at the same or different speeds
D. All A., B. and C.
Rittinger number which designates the new surface produced per unit of mechanical energy absorbed by the material being crushed, depends on the ______________________?
A. State or manner of application of the crushing force
B. Ultimate strength of the material
C. Elastic constant of the material
D. All A., B. and C.
Sedimentation on commercial scale occurs in____________________?
A. Classifiers
B. Thickeners
C. Rotary drum filters
D. Cyclones
Rod mills employed for grinding_________________?
A. Employ a steel shell having L/D ratio of 1.5 to 3.0
B. Is useful for handling sticky materials
C. Employ steel rods of 2-12 cms diameter extending over full length of the mill
D. All A , B & C
Which of the following oxides is not present in hematite iron ore ?
A. Titanium oxide
B. Calcium oxide
C. Cobalt oxide
D. Manganese oxide
The main size reduction operation in ultrafine grinders is_____________?
A. Cutting
B. Attrition
C. Compression
D. Impact
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