Description : The specific surface of spherical particles is proportional to (where, Dp = diameter of particle). (A) D2 p (B) Dp (C) 1/Dp (D) 1/D2p
Last Answer : (C) 1/Dp
Description : For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter). (A) 1/D (B) 1/D2 (C) 1/D5 (D) D
Last Answer : (C) 1/D5
Description : At low Reynold's number, the power (P) required for agitating a fluid in a stirred tank becomes independent of inertial forces. In this limit, indicate which of the following relations is satisfied: Po = ρ/ρN3 D5 : Power number Re = ρ N D2 ... Re -1.0 (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5 (D) Po ∝ Re 1.0
Last Answer : (B) Po ∝ Re 0.0 (C) Po ∝ Re 0.5
Description : A tube mill as compared to a ball mill (A) Employs smaller balls (B) Gives finer size reduction but consumes more power (C) Has larger length/diameter ratio (>2 as compared to 1 for ball mill) (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : 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
Last Answer : (D) 0.66
Description : Length/diameter ratio of a ball mill is (A) 1.5 (B) 1 (C) < 1 (D) > 1
Last Answer : (C) < 1
Description : Tube mill compared to ball mill (A) Produces finer products (B) Is long in comparison with its diameter (C) Uses smaller balls (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : In ball mill operation, the feed size (Df in meters) and the ball diameter (Db in metres) are related as (where, K = grindability constant (varying from 0.9 to 1.4 in increasing order of hardness)) (A) Db 2 = K.Df (B) Db = K.Df (C) Db 3 = K.Df (D) Db 2 = K.Df
Last Answer : (A) Db 2 = K.Df
Description : 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
Last Answer : (A) Length to diameter ratio
Description : A tube mill compared to a ball mill (A) Has a higher length/diameter ratio (B) Produces a coarser product (C) Has a higher diameter/length ratio (D) Uses much larger balls
Last Answer : (A) Has a higher length/diameter ratio
Description : According to the film theory of mass transfer, the mass transfer coefficient is proportional to (where, D = molecular diffusivity). (A) D (B) D2 (C) D0.5 (D) 1/D
Last Answer : (A) D
Description : The energy consumed by a ball mill depends on (A) Its speed (B) Its ball load (C) The density of the material being ground (D) All (A), (B) and (C)
Description : Which of the following gives the work required for size reduction of coal to -200 mesh in a ball mill most accurately? (A) Rittinger's law (B) Kick's law (C) Bond's law (D) None of these
Last Answer : (A) Rittinger's law
Description : Power required by a centrifugal pump is proportional to (where, D = diameter, N = r.p.m) (A) N2D3 (B) ND2 (C) N2D (D) N3D5
Last Answer : (D) N3D5
Description : In a fully turbulent flow (Re > 10 5 ) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is (A) d (B) d 2 (C) d 2.5 (D) d
Last Answer : (C) d 2.5
Description : The life of a ball bearing is inversely proportional to (A) (Load)1 (B) (Load)2 (C) (Load)3 (D) (Load)0.33
Last Answer : (C) (Load)3
Description : rpm of a trommel at critical speed is given by (where, D = Diameter of trommel in ft) (A) 76.65/D (B) 76.65/√D (C) 76.65/D2 (D) 76.75 √D
Last Answer : (B) 76.65/√D
Description : For spheres, the surface shape factor is given by (where, A = area, V = volume, and D = diameter) (A) π = (A/D2 ) (B) π/6 = (V/D3 ) (C) AD/V (D) None of these
Last Answer : (A) π = (A/D2 )
Description : Pick out the wrong statement. (A) The equivalent stiffness of two springs (of equal stiffness 'S') in series is S/2 while in parallel is 2S (B) For a helical spring, deflection is ... is less than the buckling load (D) Modulus of resilience is proportional to (stress at elastic limit)2
Last Answer : (C) Crushing load or columns is less than the buckling load
Description : Rittinger's crushing law states that (A) Work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product (B) Work required to form a ... ) For a given machine and feed, crushing efficiency is dependent on the size of the feed & product
Last Answer : (C) Work required in crushing is proportional to the new surface created
Description : In case of grinding in a ball mill (A) Wet grinding achieves a finer product size than dry grinding (B) Its capacity decreases with increasing fineness of the products (C) Grinding cost and power requirement increases with increasing fineness of the products (D) All (A), (B) and (C)
Description : A compound pipe of diameter d1, d2 and d3 having lengths l1, l2 and l3 is to be replaced by an equivalent pipe of uniform diameter d and of the same length (l) as that of the compound pipe. The size of the equivalent pipe is given by (A) l/d² = + + (B) l/d³ = + ) + (C) = + + (D)
Last Answer : Answer: Option D
Description : The torque transmitted by a hollow shaft of outer diameter (D) and inner diameter (d) (a)π/4fs(D2-d2)/D (b) π/4fs(D3-d3)/D (c) π/4fs(D4-d4)/D (d) π/4fs(D4-d4)/D
Last Answer : (c) π/4fs(D4-d4)/D
Description : When two concentric springs are made of same material, having same free length and compressed equally by axial load, then the load shared by each spring is proportional to (A) Spring index of each spring ... spring (C) Mean coil diameter of each spring (D) Square of wire diameter of each spring
Last Answer : (D) Square of wire diameter of each spring
Description : The external load per unit length of (A) A pipe laid on, or projecting above the undisturbed ground and covered with fills, is proportional to the square of the external diameter of the pipe ... fills, is proportional to the square of the width of the trench (D) All the above
Last Answer : (D) All the above
Description : Grinding efficiency of a ball mill is of the order of __________ percent. (A) 1-5 (B) 40-50 (C) 75-80 (D) 90-95
Last Answer : (A) 1-5
Description : Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases. (A) ... the pump (C) Head of the liquid pumped (D) All (A), (B) and (C)
Description : Run of mine (ROM) coal is crushed by a __________ for use in domestic ovens. (A) Jaw crusher (B) Hammer crusher (C) Ball mill (D) Tube mil
Last Answer : (B) Hammer crusher
Description : A pebble mill (A) Is a ball mill (B) Employs flints or ceramic pebbles as the grinding medium (C) Is a tube mill lined with ceramic or other non-metallic liner (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : 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
Last Answer : (C) 50
Description : Which of the following crushers can be considered as a combination of a jaw crusher and a roller crusher? (A) Rod mill (B) Fluid energy mill (C) Gyratory crusher (D) Ball mill
Last Answer : (C) Gyratory crusher
Description : Energy requirement (per unit mass of material crushed/ground) is highest for (A) Jaw crusher (B) Rod mill (C) Ball mill (D) Fluid energy mil
Last Answer : (D) Fluid energy mil
Description : For the preliminary breaking of hard rock, we use a (A) Gyratory crusher (B) Ball mill (C) Tube mill (D) Squirrel-cage disintegrator
Last Answer : (A) Gyratory crusher
Description : For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a (A) Buhrstone mill (B) Ball mill (C) Crushing rolls (D) Hammer mill
Last Answer : (A) Buhrstone mill
Description : Out of the following size reduction equipments, the maximum feed size can be accepted by the (A) Tube mill (B) Ball mill (C) Jaw crusher (D) Jet pulveriser
Last Answer : (C) Jaw crusher
Description : To get ultrafine particles, the equipment used is a (A) Ball mill (B) Rod mill (C) Hammer crusher (D) Fluid energy mill
Last Answer : (D) Fluid energy mill
Description : __________ balls capable of grinding the feed in a ball mill gives the maximum efficiency. (A) Cast iron (B) Minimum size (C) Maximum size (D) Elliptical
Last Answer : (B) Minimum size
Description : Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them. (A) Jaw crusher, Ball mill, Fluid energy mill (B) Ball mill, Jaw crusher, Fluid ... C) Fluid energy mill, Jaw crusher, Ball mill (D) Fluid energy mill, Ball mill, Jaw crusher
Last Answer : (A) Jaw crusher, Ball mill, Fluid energy mill
Description : . To produce talcum powder, use (A) Ball mill (B) Hammer mill (C) Jet mill (D) Pin mill
Last Answer : (A) Ball mill
Description : Limestone is normally crushed in a (A) Roll crusher (B) Hammer crusher (C) Ball mill (D) Tube mill
Description : Coal is finally pulverised to 200 mesh size for burning in boilers by a (A) Hammer crusher (B) Ball mill (C) Roll crusher (D) Gyratory crusher
Last Answer : (B) Ball mill
Description : Ball mill is used for (A) Crushing (B) Coarse grinding (C) Fine grinding (D) Attrition
Last Answer : (C) Fine grinding
Description : 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
Last Answer : (A) Less than
Description : Feed size of ≥ 25 cms can be accepted by (A) Ball mill (B) Rod mill (C) Fluid energy mill (D) Jaw crusher
Last Answer : (D) Jaw crusher
Description : A __________ mixer resembles a ball mill without balls. (A) Banbury (B) Pug mill (C) Tumbling (D) Pan
Last Answer : (C) Tumbling
Description : Fibrous material is broken by a (A) Roll-crusher (B) Squirrel-cage disintegrator (C) Ball mill (D) Tube mill
Last Answer : (B) Squirrel-cage disintegrator
Description : Close circuit grinding by a ball mill with air sweeping employs a (A) Classifier (B) Cyclone separator between mill & classifier (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : Maximum size reduction in a ball mill is done by the, __________ action. (A) Attrition (B) Compression (C) Impact (D) Cutting
Last Answer : (C) Impact
Description : 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) ... of large particles (upto 1.25 cms) (D) Dry grinding of large particles in un-baffed mills
Last Answer : (D) Dry grinding of large particles in un-baffed mills
Description : 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)
Last Answer : (B) Nc = (1/2π). √(g/R1 - R2 )