Practice Test: Question Set - 26
1. Mixing of light fine powder such as insecticides is done by
- (A) Banbury mixer
- (B) Pug mill
- (C) Impact wheels
- (D) Kneader
2. Velocity of a small particle of diameter 'Dp' at a distance 'r' from the rotational axis of a cyclone rotating at an angular speed 'ω' is given by (the other symbols are as per standard notation).
- (A) [(DP/18). (ρs -
ρ/µ)] ω2r
- (B) [(DP2/18).
(ρs - ρ/µ)] ω2r
- (C) [(DP/18). (ρs -
ρ/µ)] ω2r2
- (D) [(DP2/18).
(ρs - ρ/µ)] ω2r
3. Energy consumption in a crusher decreases with increase in the
- (A) Size of the product (at constant feed size)
- (B) Capacity of the crushing machine
- (C) Size of feed (at constant reduction ratio)
- (D) All (a), (b) & (c)
4. Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm)?
- (A) Trough washer
- (B) Baum jig washer
- (C) Spiral separator
- (D) Froth floatation
5. 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
6. The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is
- (A) 1.5
- (B) 1
- (C) √2
- (D) None of these
7. Filter medium resistance is that offered by the
- (A) Filter cloth
- (B) Embedded particles in the septum
- (C) Filter cloth and the embedded particle collectively
- (D) None of these
8. Which of the following is not a cutting machine?
- (A) Dicers
- (B) Knife cutters
- (C) Slitters
- (D) Tube mills
9. Crushing of mineral particles is accomplished in a 'cage mill', when one or more alloy steel bars are revolved in opposite directions. It is a type of __________ mill.
- (A) Impact
- (B) Roll
- (C) Vibratory
- (D) None of these
10. The sphericity of a cylinder of 1 mm diameter and length 3 mm is
- (A) 0.9
- (B) 0.78
- (C) 0.6
- (D) 0.5
11. A compressible cake has the
- (A) Maximum porosity at the upstream side
- (B) Maximum porosity at the filter medium
- (C) Same porosity throughout the cake thickness
- (D) None of these
12. Separation of materials into products based on the difference of their sizes is called
- (A) Sizing
- (B) Sorting
- (C) Classification
- (D) Flocculation
13. 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
14. Ultra centrifuges are used for the separation of __________ solid particles.
- (A) Coarse
- (B) Fine
- (C) Colloidal
- (D) Dissolved
15. Filter medium resistance is important during the __________ of filtration.
- (A) Early stages
- (B) Final stages
- (C) Entire process
- (D) None of these
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