A. Plastic chips are called non-cohesive solids
B. Kick’s crushing law is, P/m = K . ln (D̅ sa/D̅ sb)
C. Communition is a generic term for size enlargement operation
D. Energy required in kwh per ton of product, such that 80% of it passes through a 200 mesh
screen, is called ‘Work index’
Related Mcqs:
- Pick out the correct statement?
A. Angle of repose is always greater than the angle of slide
B. A hopper is a small bin with a sloping bottom
C. A silo is a short height vessel of very large diameter used for the storage of high volatile
matter coal
D. Pine oil is used as a ‘modifying agent’ (for activating or depressing the adsorption of filming
agents) in froth floatation process - Pick out the correct statement ?
A. Removal of iron from ceramic material is necessitated (by magnetic separation method) so as
to avoid discolouration of ceramic products
B. The operating cost of shaking screen is more than that of a vibrating screen
C. Screen capacity does not depend upon the specific gravity of the minerals
D. Asphalt is best crushed using toothed roll crusher - Pick out the correct statement?
A. The capacity and the effectiveness of a screen are the same
B. The capacity and the effectiveness of screen are opposing factors
C. The screening surface of a ‘reel’ (a revolving screen used in flour mills) is made of silk bolting
cloth supported by wire mesh
D. Both B. and C. - Pick out the wrong statement ?
A. Magnetic separation method can be employed to treat both dry & wet ores
B. Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the
maximum product size
C. Gyratory crusher is used for coarse crushing
D. Screens are of stationary, moving and vibratory types - Pick out the wrong statement ?
A. For the compressible cake, voidage & the specific resistance of the cake can be assumed to be
constant
B. Cake resistance is independent of the pressure drop
C. Crushing of explosive materials are done by employing dry-grinding
D. Gyratory crusher is a coarse crusher - Pick out the wrong statement pertaining to the turbine agitator ?
A. Recommended peripheral speed for the turbine agitator is 200-250 metres/minute
B. Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow
C. Generally, the diameter of the agitator is kept between l/3rd to l/6th of the tank diameter while
the blade length is l/4th of agitator diameter (with central disc, it is l/8th of the agitator
diameter)
D. Turbine agitator should be located at a height not less than one agitator diameter length from
the bottom. If the depth of liquid in the tank is more than twice the agitator diameter, two
agitators should be used - Pick out the wrong statement pertaining to the roll crushers?
A. Maximum feed size determines the required roll diameter
B. For hard material’s crushing, the reduction ratio should not exceed 4
C. Both the rolls run necessarily at the same speed
D. Reduction ratio and differential roll speed affect production rate & energy consumed per unit
of surface produced - Pick out the wrong statement?
A. Recycled coarse material to the grinder by a classifier is termed as circulating load
B. Wear and tear in wet crushing is more than that in dry crushing of materials
C. Size enlargement (opposite of size reduction) is not a mechanical operation
D. A ‘dust catcher’ is simply an enlargement in a pipeline which permits the solids to settle down
due to reduction in velocity of the dust laden gas - Pick out the wrong statement ?
A. Gape is the greatest distance between the crushing surfaces or the jaws
B. The angle of nip (2α) is the angle between roll faces at the level where they will just take hold
of a particle and draw it in the crushing zone
C. Crushing efficiency is the ratio of the energy absorbed by the solid to the surfaces energy
created by crushing
D. Reduction ratio is the ratio of the maximum size of the particles in the feed to that in the
product - 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
