The mechanism of size reduction by a hammer mill is by impact and attrition between the________________?

Related Mcqs:

1. In a ball mill, the volume occupied by the balls (when the mill is stopped) is about _______________ percent of the volume of the mill?

   A. 35
   B. 50
   C. 70
   D. 85

2. Which of the following size reduction equipments employs mainly attrition for ultrafine grinding ?

   A. Jet mills
   B. Fluid energy mill
   C. Micronizer
   D. All A., B. and C.

3. The main differentiation factor between tube mill and ball mill is the ___________________?

   A. Length to diameter ratio
   B. Size of the grinding media
   C. Final product size
   D. Operating speed

4. Critical Speed (Nc) of a ball mill is given by (where R1 and R2 are radii of ball mill and the ball respectively) ?

   A. Nc = (1/4π). √(g/R1 – R2)
   B. Nc = (1/2π). √(g/R1 – R2)
   C. Nc = (1/π). √(g/R1 – R2)
   D. Nc = (1/2π). √(R1 – R2/g)

5. ______________ mill is not a revolving mill ?

   A. Pebble
   B. Compartment
   C. Cage
   D. Tube

6. For achieving maximum capacity of the ball mill, the ball charge should be equal to about ______________ percent of the ball mill volume?

   A. 10
   B. 25
   C. 50
   D. 75

7. Crushing of mineral particles is accomplished in a ‘cage mill’, when one or more alloy steel bars are revolved in opposite directions. It is a type of ______________ mill?

   A. Impact
   B. Roll
   C. Vibratory
   D. None of these

8. Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill.) ?

   A. D
   B. 1/D
   C. D2.5
   D. 1/D2.5

9. A _____________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end?

   A. Compartment
   B. Tube
   C. Rod
   D. Pebble

10. Actual operating speed of a ball mill may vary from 65 to 80% of the critical speed. Which of the following duties would require the ball mill to be operated at maximum percentage of critical speed ?

    A. Wet grinding in low viscous suspension
    B. Wet grinding in high viscous suspension
    C. Dry grinding of large particles (upto 1.25 cms)
    D. Dry grinding of large particles in un-baffed mills