Mechanical Operations

161. Horsepower required for a roll crusher is directly proportional to its

1. Reduction ratio
2. Capacity
3. Both (A) & (B)
4. Neither (A) nor (B)

View answer

162. Hot, lumpy & abrasive materials are best transported by using a/an _________ conveyor.

1. Apron
2. Belt
3. Screw
4. Flight

View answer

163. If a force greater than that of gravity is used to separate solids & fluids of different densities, the process is termed as the

1. Sedimentation
2. Flocculation
3. Dispersion
4. Centrifugation

View answer

164. If dp is the equivalent diameter of a non-spherical particle, V_p its volume and sp its surface area, then its sphericity is φ_s is defined by

1. φ_s = 6 V_p/d_ps_p
2. φ_s = V_p/d_ps_p
3. φ_s = 6 d_pS_p/V_p
4. φ_s = d_pS_p/V_p

View answer

165. If radius of a batch basket centrifuge is halved & the r.p.m. is doubled, then the

1. Linear speed of the basket is doubled
2. Linear speed of the basket is halved
3. Centrifugal force is doubled
4. Capacity of centrifuge is increased

View answer

166. In a ball mill, the volume occupied by the balls (when the mill is stopped) is about _________ percent of the volume of the mill.

1. 35
2. 50
3. 70
4. 85

View answer

167. In a grinding operation, the limiting particle size is the size of the _________ particle in the sample.

1. Smallest
2. Largest
3. Either (A) or (B)
4. Neither (A) nor (B)

View answer

168. In a mixer, the quantity, (v. L/D) is termed as _________ number (where, v = longitudinal velocity of material, L = length of the mixer, D = diffusivity in axial mixing).

1. Weber
2. Peclet
3. Brinkman
4. Schmidt

View answer

169. In a roll crusher, both the rolls

1. Have the same diameter
2. Are rotated towards each other
3. Run either at the same or different speeds
4. All (A), (B) and (C)

View answer

170. In a roll crusher, the specific power consumption and the production rate is affected by the

1. Reduction ratio
2. Differential roll speed
3. Both (A) and (B)
4. Neither (A) nor (B)

View answer