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  • Question
  • Pick out the wrong statement:


  • Options
  • A. Magnetic separation method can be employed to treat both dry & wet ores.
  • B. Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size.
  • C. Gyratory crusher is used for coarse crushing.
  • D. Screens are of stationary, moving and vibratory types.

  • Correct Answer
  • Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size. 


  • Mechanical Operations problems


    Search Results


    • 1. Pick out the correct statement.

    • Options
    • A. Angle of repose is always greater than the angle of slide.
    • B. A hopper is a small bin with a sloping bottom.
    • C. A silo is a short height vessel of very large diameter used for the storage of high volatile matter coal.
    • D. Pine oil is used as a 'modifying agent' (for activating or depressing the adsorption of filming agents) in froth floatation process.
    • Discuss
    • 2. The specific surface of sherical particles is proportional to (where, Dp = diameter of particle).

    • Options
    • A. D2p
    • B. Dp
    • C. 1/Dp
    • D. 1/D2p
    • Discuss
    • 3. A gravity decanter is meant for the separation of two __________ density.

    • Options
    • A. immiscible liquids of different
    • B. miscible liquids of different
    • C. immiscible liquids of same
    • D. miscible liquids of same
    • Discuss
    • 4. Filtration should be stopped in a filter press, if the

    • Options
    • A. cake becomes very dense.
    • B. liquor stops flowing out to the discharge.
    • C. filtration pressure rises suddenly.
    • D. both(b)&(c).
    • Discuss
    • 5. In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the __________ crushing.

    • Options
    • A. primary
    • B. secondary
    • C. fine
    • D. ultrafine
    • Discuss
    • 6. During agitation of liquids, the

    • Options
    • A. Froude number is independent for the curves between power number and Reynolds number in baffled system.
    • B. Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller.
    • C. Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number.
    • D. all (a), (b) and (c).
    • Discuss
    • 7. Pick out the wrong statement.

    • Options
    • A. For the compressible cake, voidage & the specific resistance of the cake can be assumed to be constant.
    • B. Cake resistance is independent of the pressure drop.
    • C. Crushing of explosive materials are done by employing drygrinding.
    • D. Gyratory crusher is a coarse crusher.
    • Discuss
    • 8. In closed circuit grinding as compared to open circuit grinding, the

    • Options
    • A. specific surface of product is more.
    • B. product has lesser size uniformity.
    • C. production rate at a given limiting size is lower.
    • D. operation is economical.
    • Discuss
    • 9. Pick out the wrong statement.

    • Options
    • A. More commonly used jaw crusher between Dodge jaw crusher and Blake jaw crusher is the later one.
    • B. There are only four methods namely compression, impact, attrition and cutting, which the size reduction equipments employ.
    • C. Cutting machines mainly employ 'attrition' for size reduction of solids.
    • D. Operating principles of Dodge and Blake jaw crushers are combined in the working of universal jaw crushers.
    • Discuss
    • 10. The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.

    • Options
    • A. vacuum
    • B. sand
    • C. plate & frame
    • D. rotary
    • Discuss


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