Mechanical Operations Apr'2000
Part A

  1. Give the shape factor for a cylinder whose length equals its diameter.
  2. In screen analysis notation +5mm/-10mm means what?
  3. Define sphericity for a non-spherical particle
  4. Which is the most suitable equipment for removing the fine dust particle of less than one micron dia from air?
  5. Define crushing efficiency
  6. What is the advantage of wet grinding over dry grinding?
  7. Define work index
  8. What are the factors that affect energy consumption in a ball mill?
  9. Explain the term sedimentation
  10. Define hindered settling
  11. Explain the principle and application of centrifuge
  12. What is froth flotation? Discuss its applications
  13. The rate of filtration depends on what?
  14. What are the good qualities of a filter media?
  15. What are filter aids? Name few commonly used filter aids
  16. Differentiate between incompressible cake and compressible cake
  17. What are the purpose of agitation?
  18. Define flow number
  19. Name the agitator which is suitable for mixing low viscosity fluids
  20. What are the types of mixers suitable for pastes and plastic masses?
  21. Part B

  22. (a) Classify screening equipment and discuss any one with neat sketch

    (b) Explain the principle of magnetic separation methods

  23. Or
  24. (a) One tonne per hour of dolomite is produced by a ball mill operating in closed circuit with a 100 mesh screen. The screen analysis (weight %) is given below. Calculate the screen efficiency.

    Mesh

    Feed

    Oversize

    Undersize

    35

    7.07

    13.67

    0

    48

    16.60

    32.09

    0

    65

    14.02

    27.12

    0

    100

    11.82

    20.70

    2.32

    150

    9.07

    4.35

    14.32

    200

    7.62

    2.07

    13.34

    -200

    33.80

    0

    70.02

     

    100

    100

    100

    (b) Give the various methods for storage of solids. Discuss them briefly

  25. What are the various types of crushers? Give some type of crusher and explain any one of them with neat diagram.

    Or
  26. A material is crushed in a jaw crusher and the average size of the particle is reduced from 5 cm to 1.3 cm with consumption of energy at the rate of 37 Watt.hr/ton. What will be the consumption of energy necessary to crush the same material of average size 8 cm to an average size 3 cm. The mechanical efficiency remains same. (a) using Rittinger's law; (b) using Kick's law.

  27. (a) Explain the term "Terminal settling velocity" of a particle.

    (b) Derive an equation for the terminal settling velocity of a particle in the Stoke's law and Newton's law range.

  28. Or
  29. Discuss the basic principles involved in the beneficiation of ores by Froth flotation. With suitable examples explain the roll of collectors, frothers and modifiers in the operation.

  30. (a) With a neat sketch explain the working of a plate and frame filter press.

    (b) Discuss the basic principles of centrifugal filtration.

  31. Or
  32. (a) Derive an expression for determining the specific resistance of the cake during filtration.

    (b) A rotary filter operating at 2 rpm, filters 1000 lit/min. Operating under the same vacuum and neglecting the resistance of the filter cloth, at what speed must the filter be operated to give a filtration rate of 2000 lit/min.

  33. (a) Classify mixers for dry powders and state their specific application.

    (b) What are the preventive measures for reducing swirling in agitated tanks?

    (c) Explain any one type of mixers suitable for pastes and plastic masses.

  34. Or
  35. Derive an expression for calculating power consumption in agitating Newtonian fluid by using dimensional analysis and state physical significance of each dimensionless number obtained in above expression.