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  • Question
  • Which of the following is not an ultrafine grinder (colloid mill)?


  • Options
  • A. Micronizers
  • B. Agitated mills and fluid energy mills
  • C. Toothed roll crusher
  • D. Hammer mills with internal classification

  • Correct Answer
  • Toothed roll crusher 


  • Mechanical Operations problems


    Search Results


    • 1. __________ centrifuge is normally used in sugar mills.

    • Options
    • A. Tubular bowl
    • B. Disc-bowl
    • C. Suspended batch basket
    • D. Perforated horizontal basket continuous
    • Discuss
    • 2. Filter aid is used to

    • Options
    • A. increase the rate of filtration.
    • B. decrease the pressure drop.
    • C. increase the porosity of the cake.
    • D. act as a support base for the septum.
    • Discuss
    • 3. Equivalent diameter of a particle is the diameter of the sphere having the same

    • Options
    • A. ratio of surface to volume as the actual volume.
    • B. ratio of volume to surface as the particle.
    • C. volume as the particle.
    • D. none of these.
    • Discuss
    • 4. Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.

    • Options
    • A. flight
    • B. slat or drag
    • C. ribbon
    • D. screw
    • Discuss
    • 5. The main size reduction operation in ultrafine grinders is

    • Options
    • A. cutting
    • B. attrition
    • C. compression
    • D. impact
    • Discuss
    • 6. Size reduction of __________ is accomplished in steam heated rollers and roll crushers.

    • Options
    • A. resins
    • B. gums
    • C. hard rubber
    • D. waxes
    • Discuss
    • 7. For a non-spherical particle, the sphericity

    • Options
    • A. is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
    • B. has the dimension of length.
    • C. is always less than 1.
    • D. is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle.
    • Discuss
    • 8. Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of

    • Options
    • A. bronze
    • B. stainless steel
    • C. flint or porcelain
    • D. concrete
    • Discuss
    • 9. In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the

    • Options
    • A. square root of the velocity.
    • B. square of the viscosity.
    • C. filtration time only.
    • D. washing time only.
    • Discuss
    • 10. Pick out the correct statement:

    • Options
    • 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.
    • Discuss


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