Theoretical capacity of crushing rolls in tons/hr is given by (where, V = peripheral velocity, m/sec. W = width of rolls, m Dr = distance between rolls ρ = density of material to be crushed, kg/m3 here, V =πND where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m) ?

Related Mcqs:

1. Critical speed of rotation, N (in rps – rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec2 and, r = radius of trammel, metre.) ?

   A. (1/2π). √(g/r)
   B. (1/π). √(g/r)
   C. ½ √(g/r)
   D. 2π. √(g/r)

2. Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ρ = bulk density of material, kg/m3) ?

   A. 3.6 W.D.V.ρ
   B. 3.6 W.D.V
   C. 3.6 W.V.ρ
   D. 3.6 D.V.ρ

3. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is ___________________?

   A. ½w2 . R2 . ρL
   B. ½w2 . δ2 . ρL
   C. ½w2 . δρL (2R + δ)
   D. ½w2 . R . ρL(R + 2δ)

4. The capacity of a classifier in ‘tons of solid/hr’ is given by (where, A = cross-sectional area in m2, V = rising velocity of fluid in m/sec, S = percentage of solids in the suspension by volume, ρ = density of solids in kg/m3)_________________?

   A. 3.6 AVS.ρ
   B. 3.6 A.V.ρ
   C. 3.6 A.S. ρ
   D. 3.6 AVS/ρ
   Answer: Option

5. Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively) ?

   A. cos α = (dr + dp)/(dr + df)
   B. cos α = (dr + df)/(dr + dp)
   C. tan α = (dr + dp)/(dr + df)
   D. sin α = (dr + dp)/(dr + df)

6. 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

7. What is the critical rotation speed in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm dia balls ?

   A. 0.5
   B. 1.0
   C. 2.76
   D. 0.66

8. Velocity of a small particle of diameter ‘Dp’ at a distance ‘r’ from the rotational axis of a cyclone rotating at an angular speed ‘ω’ is given by (the other symbols are as per standard notation) ?

   A. [(DP/18). (ρs – ρ/μ)] ω2r
   B. [(DP2/18). (ρs – ρ/μ)] ω2r
   C. [(DP/18). (ρs – ρ/μ)] ω2r2
   D. [(DP2/18). (ρs – ρ/μ)] ω2r

9. 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.

10. 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