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  • Question
  • Coal is finally pulverised to 200 mesh size for burning in boilers by a


  • Options
  • A. hammer crusher
  • B. ball mill
  • C. roll crusher
  • D. gyratory crusher

  • Correct Answer
  • ball mill 


  • Mechanical Operations problems


    Search Results


    • 1. Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids ( > 50000 centipoise)?

    • Options
    • A. Propeller
    • B. Helical screw
    • C. Flat blade turbine
    • D. Curved blade turbine
    • Discuss
    • 2. The controlling resistance in a rotary drum vacuum filter is the __________ resistance.

    • Options
    • A. piping
    • B. cake
    • C. filter medium
    • D. none of these
    • Discuss
    • 3. Which is the most suitable conveyor for transportation of sticky material?

    • Options
    • A. Apron conveyor
    • B. Belt conveyor
    • C. Screw conveyor
    • D. Pneumatic conveyor
    • Discuss
    • 4. Screen capacity is not a function of

    • Options
    • A. its openings size.
    • B. screening mechanism.
    • C. screening surface.
    • D. atmospheric humidity.
    • Discuss
    • 5. A tube mill compared to a ball mill

    • Options
    • A. has a higher length/diameter ratio.
    • B. produces a coarser product.
    • C. has a higher diameter/length ratio.
    • D. uses much larger balls.
    • Discuss
    • 6. For spheres, volume shape factor is given by

    • Options
    • A. ?(=A/D2)
    • B. 2?(=2A/D2)
    • C. ?/6(=V/D3)
    • D. AD/V
    • Discuss
    • 7. Basic slag is not ground in

    • Options
    • A. jaw crushers
    • B. ball mills
    • C. compartment mills
    • D. tube mills
    • Discuss
    • 8. Length/diameter ratio of a ball mill is

    • Options
    • A. 1.5
    • B. 1
    • C. < 1
    • D. > 1
    • Discuss
    • 9. A tube mill as compared to a ball mill

    • Options
    • A. employs smaller balls.
    • B. gives finer size reduction but consumes more power.
    • C. has larger length/diameter ratio (>2 as compared to 1 for ball mill).
    • D. all (a), (b) and (c).
    • Discuss
    • 10. Bucket elevators are not suitable for the vertical lifting of __________ materials.

    • Options
    • A. fine (e.g. - 200 mesh size coal)
    • B. sticky (e.g. clay paste)
    • C. small lumpy (e.g. grains and sand)
    • D. free flowing
    • Discuss


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