A. 0.33-0.45
B. 1.33-1.45
C. 0.5-2
D. 1.5-2.5
Related Mcqs:
- 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 - The critical speed of a trommel (N) is related to its dia D. as _____________________?
A. N ∝ 1/√D
B. N ∝ √D
C. N ∝ D
D. N ∝ 1/D - The operating speed of a ball mill should be ______________ the critical speed?
A. Less than
B. Much more than
C. At least equal to
D. Slightly more than - 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) - 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) - 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 - 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) - 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 - For raschig rings, the sphericity is_____________________?
A. 0.5
B. 1
C. < 1
D. √3 - Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is_____________________?
A. 0.01 to 0.1
B. 0.1 to 0.3
C. 0.2 to 0.8
D. 0.2 to 0.4