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Chemical Engineering :: Mechanical Operations

  1. Which of the following mineral dressing operations is termed as 'comminution'?

  2. A.
    Panning
    B.
    Spiralling
    C.
    Tabling
    D.
    None of these

  3. The capacity of a pneumatic conveying system depends upon the

  4. A.
    bulk density of materials.
    B.
    pressure of the conveying air.
    C.
    diameter of the conveying line.
    D.
    all (a), (b) and (c).

  5. Pick out the wrong statement.

  6. A.
    Close circuit grinding is more economical than open circuit grinding.
    B.
    Cod oil, beef tallow or aluminium stearates are used as grinding aids in cement 'industries'.
    C.
    The equipment used for the removal of traces of solids from a liquid is called a classifier.
    D.
    Size enlargement is a mechanical operation exemplified by medicinal tablet making.

  7. Gravity settling process is not involved in the working of a

  8. A.
    hydrocyclone
    B.
    classifier
    C.
    dorr-thickener
    D.
    sedimentation tank

  9. Froth floatation is the most suitable for treating

  10. A.
    iron ores
    B.
    sulphide ores
    C.
    quartzite
    D.
    none of these

  11. The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size to 50 μrn is

  12. A.
    6.35 kWh/ton
    B.
    9.0 kWh/ton
    C.
    18 kWh/ton
    D.
    25.4 kWh/ton

  13. Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?

  14. A.
    Trough washer
    B.
    Baum jig washer
    C.
    Spiral separator
    D.
    Froth floatation

  15. Pick out the correct statement:

  16. 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.

  17. Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is

  18. A.
    0.01 to 0.1
    B.
    0.1 to 0.3
    C.
    0.2 to 0.8
    D.
    0.2 to 0.4

  19. Highly viscous liquids & pastes are agitated by

  20. A.
    propellers
    B.
    turbine agitators
    C.
    multiple blade paddles
    D.
    none of these