The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond’s law) of the energy to grind the particles from a very large size to 50 μm is________________?

Related Mcqs:

1. Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with ______________ to get the same for dry grinding?

   A. 1.0
   B. 0.5
   C. 1.34
   D. 4.34

2. Energy consumed for crushing one ton of material ranges from ______________ kWh?

   A. 0.01 to 0.1
   B. 0.5 to 1.5
   C. 2 to 3.5
   D. 4 to 5

3. Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, Vp = volume of one particle, ρ= density of particles) ?

   A. m/ρ . Vp
   B. m . ρ/Vp
   C. m . Vp/ρ
   D. Vp/m . ρ

4. Kick’s law assumes that the energy required for size reduction is proportional to the logarithm of the ratio between the initial and the final diameters. The unit of Kick’s constant is_________________?

   A. kW. sec/kg
   B. kWh/kg
   C. kWh/sec. kg
   D. kg/sec

5. Energy requirement (per unit mass of material crushed/ground) is highest for__________________?

   A. Jaw crusher
   B. Rod mill
   C. Ball mill
   D. Fluid energy mill

6. According to Bond crushing law, the work required to form particle of size ‘D’ from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively) ?

   A. (S/V)p
   B. √(S/V)p
   C. (S/V)2p
   D. (S/V)f

7. ______________ are used for the separation of coarse particles from a slurry of fine particles?

   A. Thickeners
   B. Classifiers
   C. Hydrocyclones
   D. Decanters

8. The constants (Kb, Kr and Kk) used in the laws of crushing (i.e., Bond’s law, Rittinger’s law and Kick’s law) depend upon the_________________?

   A. Feed material
   B. Type of crushing machine
   C. Both A. & B.
   D. Neither A. nor B.

9. Rittinger’s number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittinger’s number of a material indicates its________________?

   A. Easier grindability
   B. Poor grindability
   C. High power consumption in grinding
   D. None of these

10. Rittinger number which designates the new surface produced per unit of mechanical energy absorbed by the material being crushed, depends on the ______________________?

    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.