Q.1

The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to

  • N°
  • N1
  • N2
  • N3
Q.2

Which is the most suitable conveyor for transportation of sticky material ?

  • Apron conveyor
  • Belt conveyor
  • Screw conveyor
  • Pneumatic conveyor
Q.3

Bond crushing law

  • calls for relatively less energy for the smaller product particles, than does the Rittinger law.
  • is less realistic in estimating the power requirements of commercial crushers.
  • states that the work required to form particle of any size from very large feed is proportional to the square root of the volume to surface ratio of the product.
  • states that the work required for the crushing is proportional to the new surface created.
Q.4

The most suitable equipment for removing the fine dust particle (< 1 micron dia.) from air below its dew point will be a/an

  • bag filter
  • electrostatic precipitator
  • cyclone separator
  • wet scrubber
Q.5

Flow of filtrate through the cake in a plate and frame filter press is best described by the __________ equation.

  • Kozney-Karman
  • Hagen-Poiseulle's
  • Fanning's
  • Kremser
Q.6

Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is

  • >10
  • <10
  • >100
  • <100
Q.7

Size reduction of __________ is accomplished in steam heated rollers and roll crushers.

  • resins
  • gums
  • hard rubber
  • waxes
Q.8

The capacity of a belt conveyor depends upon two factors. If one is the cross-section of the load, the other is the __________ of the belt.

  • speed
  • thickness
  • length
  • none of these
Q.9

Which of the following is not a part of the Blake jaw crusher?

  • Hanger
  • Check plates
  • Toggles
  • Pitman
Q.10

Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of

  • bronze
  • stainless steel
  • flint or porcelain
  • concrete
Q.11

The energy required per unit mass to grind limestone particles of very large size toμm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size toμrn is

  • 6.35 kWh/ton
  • 9.0 kWh/ton
  • 18 kWh/ton
  • 25.4 kWh/ton
Q.12

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

  • sedimentation
  • flocculation
  • dispersion
  • centrifugation
Q.13

Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is

  • added to the feed slurry.
  • precoated on the filter medium prior to filtration.
  • separated from the cake by dissolving solids or by burning it off.
  • all 'a', 'b'&'c'.
Q.14

Which of the following is the most suitable for cleaning of fine coal dust (<0.5 mm) ?

  • Trough washer
  • Baum jig washer
  • Spiral separator
  • Froth floatation
Q.15

Filter aid is used to

  • increase the rate of filtration.
  • decrease the pressure drop.
  • increase the porosity of the cake.
  • act as a support base for the septum.
Q.16

Two particles are called to be equal settling, if they are having the same.

  • size.
  • specific gravity.
  • terminal velocities in the same fluid & in the same field of force.
  • none of these.
Q.17

Which of the following relationships between co-efficinet of friction (μ) between rock & roll and a (half of the angle of nip) of the particle to be crushed is correct ?

  • μ > tan α
  • μ ≥ tan α
  • μ > tan 2α
  • μ ≤ tan α
Q.18

In continuous filtration (at a constant pressure drop), filtrate flow rate varies inversely as the

  • square root of the velocity.
  • square of the viscosity.
  • filtration time only.
  • washing time only.
Q.19

Pick out the correct statement:

  • Removal of iron from ceramic material is necessitated (by magnetic separation method) so as to avoid discolouration of ceramic products.
  • The operating cost of shaking screen is more than that of a vibrating screen.
  • Screen capacity does not depend upon the specific gravity of the minerals.
  • Asphalt is best crushed using toothed roll crusher.
Q.20

Jigging is a technique by which different particles can be

  • separated by particle size.
  • separated by particle density.
  • separated by particle shape.
  • mixed.
Q.21

Which of the following mineral dressing operations is termed as 'comminution'?

  • Panning
  • Spiralling
  • Tabling
  • None of these
Q.22

Which of the following is the most suitable for handling fibrous and dense slurries ?

  • Propeller agitator
  • Cone type agitator
  • Turbine agitator
  • Radial propeller agitator
Q.23

__________ centrifuge is normally used in sugar mills.

  • Tubular bowl
  • Disc-bowl
  • Suspended batch basket
  • Perforated horizontal basket continuous
Q.24

Pick out the wrong statement pertaining to the roll crushers.

  • Maximum feed size determines the required roll diameter.
  • For hard material's crushing, the reduction ratio should not exceed 4.
  • Both the rolls run necessarily at the same speed.
  • Reduction ratio and differential roll speed affect production rate & energy consumed per unit of surface produced.
Q.25

For sizing of fine materials, the most suitable equipment is a

  • trommel
  • grizzly
  • shaking screen
  • vibrating screen
Q.26

Range of compressibility co-efficient of the commercial compressible cake obtained in filtration operation is

  • 0.01 to 0.1
  • 0.1 to 0.3
  • 0.2 to 0.8
  • 0.2 to 0.4
Q.27

Highly viscous liquids & pastes are agitated by

  • propellers
  • turbine agitators
  • multiple blade paddles
  • none of these
Q.28

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.

  • impact
  • roll
  • vibratory
  • none of these
Q.29

The capacity of a pneumatic conveying system depends upon the

  • bulk density of materials.
  • pressure of the conveying air.
  • diameter of the conveying line.
  • all (a), (b) and (c).
Q.30

The value of 'angle of nip' is generally about

  • 16°
  • 32°
  • 52°
  • 64°
Q.31

The distribution given by microscopic analysis of powder is

  • number
  • length
  • area
  • volume
Q.32

Basic slag is not ground in

  • jaw crushers
  • ball mills
  • compartment mills
  • tube mills
Q.33

__________ mixer is used for devulcanisation of rubber scrap & making water dispersion & rubber solution.

  • Tumbler
  • Banbery
  • Muller
  • Rubbon blender
Q.34

Solid particles separation based on the difference in their flow velocities through fluids is termed as the

  • clarification
  • classification
  • elutriation
  • sedimentation
Q.35

Which of the following is not an ultrafine grinder (colloid mill)?

  • Micronizers
  • Agitated mills and fluid energy mills
  • Toothed roll crusher
  • Hammer mills with internal classification
Q.36

Which of the following is not categorised as a "mechanical operation" ?

  • Agitation
  • Filtration
  • Size enlargement
  • Humidification
Q.37

Which of the following is a pressure filter ?

  • Leaf filter (Moore filter).
  • Plate and flame filter.
  • Rotary drum filter.
  • Sand filter.
Q.38

The controlling resistance in a rotary drum vacuum filter is the __________ resistance.

  • piping
  • cake
  • filter medium
  • none of these
Q.39

The operating speed of a ball mill should be __________ the critical speed.

  • less than
  • much more than
  • at least equal to
  • slightly more than
Q.40

Filtration of water in a paper mill is done by a/an __________ filter.

  • open sand
  • plate and frame
  • vacuum leaf
  • sparkler
Q.41

Balls for ball mills are never made of

  • forged/cast steel
  • lead
  • cast iron
  • alloy steel
Q.42

Pick out the wrong statement.

  • Close circuit grinding is more economical than open circuit grinding.
  • Cod oil, beef tallow or aluminium stearates are used as grinding aids in cement 'industries'.
  • The equipment used for the removal of traces of solids from a liquid is called a classifier.
  • Size enlargement is a mechanical operation exemplified by medicinal tablet making.
Q.43

Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.

  • metalliferrous ores
  • non-metallic ores
  • basic slags
  • asbestos & mica
Q.44

Number of particles in a crushed solid sample is given by (where, m = mass of particles in a sample, Vp = volume of one particle, ρ= density of particles)

  • m/ρ . Vp
  • m . ρ/Vp
  • m . Vp/ρ
  • Vp/m . ρ
Q.45

Grindability of a material does not depend upon its

  • elasticity
  • hardness
  • toughness
  • size
Q.46

Which of the following mechanical conveyors does not come under the division 'carriers' ?

  • Belt conveyor
  • Bucket elevator
  • Screw conveyor
  • Apron conveyor.
Q.47

Diatomaceous earth is a/an

  • explosive
  • filter aid
  • filter medium
  • catalyst
Q.48

Tabular bowl centrifuges as compared to disk bowl centrifuges

  • operate at higher speed.
  • employ bowl of larger diameter.
  • can not be operated under pressure/vacuum.
  • can't be used for separation of fine suspended solids from a liquid.
Q.49

Which of the following is used for primary crushing of very hard lumpy materials ?

  • Toothed roll crusher
  • Gyratory crusher
  • Ball mill
  • Tube mill
Q.50

Use of baffles in agitators help in minimising the __________ tendency.

  • swirling
  • vortexing
  • both (a) & (b)
  • neither (a) nor (b)
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