Practice Test: Question Set - 23
1. Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.
- (A) Metalliferous ores
- (B) Non-metallic ores
- (C) Basic slags
- (D) Asbestos & mica
2. A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is
- (A) 0.1
- (B) 0.4
- (C) 0.6
- (D) None of these
3. Handling of ashes and similar materials can be done best by a __________ conveyor.
- (A) Flight
- (B) Drag or slat
- (C) Belt
- (D) Ribbon
4. Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.
- (A) Viscosity
- (B) Thermal conductivity
- (C) Surface tension
- (D) Density
5. Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher?
- (A) Rod mill
- (B) Fluid energy mill
- (C) Gyratory crusher
- (D) Ball mill
6. 200 mesh screen means 200 openings per
- (A) cm2
- (B) cm
- (C) inch
- (D) inch2
7. Which of the following terminology is not used for size reduction of materials to fine sizes or powders?
- (A) Comminution
- (B) Dispersion
- (C) Pulverization
- (D) Compression
8. A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 μm/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is
- (A) 0.90 μm/s
- (B) 1 μm/s
- (C) 22.1 μm/s
- (D) 0.02 μm/s
9. The porosity of a compressible cake is
- (A) Minimum at the filter medium
- (B) Minimum at the upstream face
- (C) Maximum at the filter medium
- (D) Same throughout the thickness of cake
10. If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is φs is defined by
- (A) φs = 6 Vp/dpsp
- (B) φs = Vp/dpsp
- (C) φs = 6 dpSp/Vp
- (D) φs = dpSp/Vp
11. The most common filter aid is
- (A) Diatomaceous earth
- (B) Calcium silicate
- (C) Sodium carbonate
- (D) Silica gel
12. Compressibility co-efficient for an absolutely compressible cake is
- (A) 0
- (B) 1
- (C) 0 to 1
- (D) ∞
13. __________ mill is normally used for grinding of talc.
- (A) Tube
- (B) Compartment
- (C) Ring-roll
- (D) Pebble
14. Which of the following is not an ultrafine grinder (colloid mill)?
- (A) Micronizers
- (B) Agitated mills and fluid energy mills
- (C) Toothed roll crusher
- (D) Hammer mills with internal classification
15. For achieving maximum capacity of the ball mill, the ball charge should be equal to about __________ percent of the ball mill volume.
- (A) 10
- (B) 25
- (C) 50
- (D) 75
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