Crushing efficiency of a machine ranges between __________________ percent?

Related Mcqs:

1. For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to __________________?

   A. The new surface created
   B. The size reduction ratio
   C. The change in volume due to crushing
   D. None of these

2. In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the ________________ crushing?

   A. Secondary
   B. Fine
   C. Primary
   D. Ultrafine

3. 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?

   A. Primary
   B. Secondary
   C. Fine
   D. Ultrafine

4. General crushing equation is given by d(P/m) = -K (dD̅ S/D̅ n S). Bond’s crushing law is obtained by solving this equation for n = _____________ and feed of infinite size?

   A. 1
   B. 1.5
   C. 2
   D. 2.5

5. In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of _______________ crushing?

   A. Primary
   B. Secondary
   C. Fine
   D. Ultrafine

6. What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?

   A. 16°
   B. 32°
   C. 40°
   D. 46°

7. 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

8. Which of the following equations is Rittinger’s crushing law? (Where P = power required by the machine, m = feed rate, k = a constant, D̅ sa & D̅ sb = volume surface mean diameter of feed & product respectively) ?

   A. P/m = K/ √Dp
   B. P/m = K . ln D̅ sa/D̅ sb
   C. P/m = K . (1/ D̅ sb – 1/D̅ sa)
   D. None of these

9. Crushing efficiency is the ratio of the ______________________ ?

   A. Surface energy created by crushing to the energy absorbed by the solid
   B. Energy absorbed by the solid to that fed to the machine
   C. Energy fed to the machine to the surface energy created by crushing
   D. Energy absorbed by the solid to the surface energy created by crushing

10. The optimum moisture content in solids to be crushed/ground ranges from _______________ percent?

    A. 3 to 4
    B. 8 to 10
    C. 10 to 15
    D. 15 to 20