Mechanical Operations

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

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.

A. Specific gravities
B. Wettability
C. Shape
D. None of these

A. Swirling
B. Vortexing
C. Both A. & B.
D. Neither A. nor B.

A. Wet grinding in low viscous suspension
B. Wet grinding in high viscous suspension
C. Dry grinding of large particles (upto 1.25 cms)
D. Dry grinding of large particles in un-baffed mills

A. Has a higher length/diameter ratio
B. Produces a coarser product
C. Has a higher diameter/length ratio
D. Uses much larger balls

A. Coarse
B. Fine
C. Any size
D. None of these

A. Specific surface of product is more
B. Product has lesser size uniformity
C. Production rate at a given limiting size is lower
D. Operation is economical

A. Metallic wire woven mesh
B. Polyester fibres
C. Cotton fibres
D. Nylon fibres

A. The new surface created
B. The size reduction ratio
C. The change in volume due to crushing
D. None of these