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  • Question
  • The reduction ratio for grinders is defined as(where, Df and Dp are average diameters of feed and product respectively).


  • Options
  • A. Df/Dp
  • B. Dp/Df
  • C. Df - Dp
  • D. none of these

  • Correct Answer
  • Df/Dp 


  • Mechanical Operations problems


    Search Results


    • 1. Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the __________ filtration.

    • Options
    • A. constant rate
    • B. varying pressure
    • C. varying rate
    • D. constant pressure
    • Discuss
    • 2. Filter medium resistance is that offered by the

    • Options
    • A. filter cloth.
    • B. embedded particles in the septum.
    • C. filter cloth and the embedded particle collectively.
    • D. none of these.
    • Discuss
    • 3. During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration

    • Options
    • A. at time zero.
    • B. at the end of filtration.
    • C. when half the filtrate has been obtained.
    • D. at the end of filtration, but decreases with time subsequently.
    • Discuss
    • 4. Tube mill compared to ball mill

    • Options
    • A. produces finer products.
    • B. is long in comparison with its diameter.
    • C. uses smaller balls.
    • D. all (a), (b) & (c).
    • Discuss
    • 5. For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter)

    • Options
    • A. ?(=A/D2)
    • B. ?/6(=V/D3)
    • C.
    • D. None of these.
    • Discuss
    • 6. Fluid energy mill comes in the category of

    • Options
    • A. grinder
    • B. crusher
    • C. cutter
    • D. ultrafine grinder
    • Discuss
    • 7. Pick out the wrong statement pertaining to the turbine agitator.

    • Options
    • A. Recommended peripheral speed for the turbine agitator is 200-250 metres/minute.
    • B. Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow.
    • C. Generally, the diameter of the agitator is kept between l/3rd to l/6th of the tank diameter while the blade length is l/4th of agitator diameter (with central disc, it is l/8th of the agitator diameter).
    • D. Turbine agitator should be located at a height not less than one agitator diameter length from the bottom. If the depth of liquid in the tank is more than twice the agitator diameter, two agitators should be used.
    • Discuss
    • 8. Rittinger number which designates the new surface prduced per unit of mechanical energy absorbed by the material being crushed, depends on the

    • Options
    • A. state or manner of application of the crushing force.
    • B. ultimate strength of the material.
    • C. elastic constant of the material.
    • D. all (a), (b) and (c).
    • Discuss
    • 9. Half the angle of nip, (?), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively).

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 10. Which one is a filter aid?

    • Options
    • A. Convas fabric
    • B. Diatomaceous earth
    • C. Calcined lime
    • D. None of these
    • Discuss


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