Question: For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to __________________?

• 1. The new surface created
• 2. The size reduction ratio
• 3. The change in volume due to crushing
• 4. None of these

Question: In bag filters, filter fabrics are never made of__________________?

• 1. Metallic wire woven mesh
• 2. Polyester fibres
• 3. Cotton fibres
• 4. Nylon fibres

Question: In closed circuit grinding as compared to open circuit grinding, the_________________?

• 1. Specific surface of product is more
• 2. Product has lesser size uniformity
• 3. Production rate at a given limiting size is lower
• 4. Operation is economical

Question: Grizzlies are used for separating _____________ solids?

• 1. Coarse
• 2. Fine
• 3. Any size
• 4. None of these

Question: A tube mill compared to a ball mill__________________?

• 1. Has a higher length/diameter ratio
• 2. Produces a coarser product
• 3. Has a higher diameter/length ratio
• 4. Uses much larger balls

Question: Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ?

• 1. Wet grinding in low viscous suspension
• 2. Wet grinding in high viscous suspension
• 3. Dry grinding of large particles (upto 1.25 cms)
• 4. Dry grinding of large particles in un-baffed mills

Question: Use of baffles in agitators help in minimising the ______________ tendency?

• 1. Swirling
• 2. Vortexing
• 3. Both A & B
• 4. Neither A nor B

Question: Ore concentration by jigging is based on the difference in the ______________ of the particles?

• 1. Specific gravities
• 2. Wettability
• 3. Shape
• 4. None of these

Question: Pick out the wrong statement ?

• 1. Hammer crushers operate by impact action
• 2. Standard screens have circular opening
• 3. With increase in mesh number of screens, their diameter in microns decreases
• 4. 200 mesh screen has 200 openings per linear cm

Question: Pick out the correct statement ?

• 1. Removal of iron from ceramic material is necessitated (by magnetic separation method) so asto avoid discolouration of ceramic products
• 2. The operating cost of shaking screen is more than that of a vibrating screen
• 3. Screen capacity does not depend upon the specific gravity of the minerals
• 4. Asphalt is best crushed using toothed roll crusher