Q.1

The ratio of the actual mesh dimension of Taylor series to that of the next smaller screen is

  • 2
  • 2
  • 1.5
  • 3
Q.2

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

  • 3.6 V.W.Dr
  • 3.6 V.W. ρ
  • 3.6 W.Dr
  • 3.6 V.W.Dr
Q.3

Percentage of drum submerged in the slurry in case of rotary drum filter is

  • 3
  • 30
  • 85
  • 25
Q.4

Trommels are revolving screens which normally operate in the range of __________ rpm.

  • 1 - 2
  • 15 - 20
  • 40 - 50
  • 60 - 75
Q.5

Which of the following screens has the maximum capacity ?

  • Grizzlies
  • Trommels
  • Shaking screen
  • Vibrating screen
Q.6

Rittinger number which designates the new surface prduced per unit of mechanical energy absorbed by the material being crushed, depends on the

  • state or manner of application of the crushing force.
  • ultimate strength of the material.
  • elastic constant of the material.
  • all (a), (b) and (c).
Q.7

The opening of amesh screen (Taylor series) is

  • 0.0074 cm
  • 0.0074 mm
  • 0.0047 cm
  • 74 mili-microns
Q.8

Ribbon blenders are exclusively meant for

  • blending miscible liquids.
  • non-flowing powder and thin pastes.
  • bath mixing.
  • continuous mixing.
Q.9

Mixing of plastic solids is generally facilitated by

  • dispersion
  • mastication
  • kneading
  • none of these
Q.10

For a cyclone of diameter 0.2 m with a tangential velocity ofm/s at the wall, the separation factor is

  • 2250
  • 1125
  • 460
  • 230
Q.11

Wet grinding in a revolving mill __________ as compared to dry grinding.

  • gives less wear on chamber walls
  • requires more energy
  • increases capacity
  • complicates handling of the product
Q.12

Filtration should be stopped in a filter press, if the

  • cake becomes very dense.
  • liquor stops flowing out to the discharge.
  • filtration pressure rises suddenly.
  • both(b)&(c).
Q.13

Which of the following clay mixing devices is vacuum operated for deairation of clay?

  • Banbery mixer
  • Pug mill
  • Muller-mixer
  • None of these
Q.14

Screen efficiency is

  • recovery/rejection
  • recovery
  • rejection
  • none of these
Q.15

Removal of activated carbon from glycerine is done by

  • plate and frame filter
  • rotary vacuum filter
  • batch basket centrifuge
  • none of these
Q.16

In case of a hammer crusher, the final product size depends on the

  • feed rate.
  • rotor speed.
  • clearance between hammer & grinding plates.
  • all (a), (b) and (c).
Q.17

__________ mill is normally used for grinding of talc.

  • Tube
  • Compartment
  • Ring-roll
  • Pebble
Q.18

Vacuum filter is most suitable for the

  • removal of fines from liquid.
  • liquids having high vapour pressure.
  • liquids of very high viscosity.
  • none of these.
Q.19

Which of the following is not accomplished by agitation of liquids in agitators?

  • Dispersing gas in liquid.
  • Blending of immiscible liquids.
  • Dispersing immiscible liquid in form of emulsion.
  • Suspending solid particles.
Q.20

The optimum moisture content in solids to be crushed/ground ranges from __________ percent.

  • 3 to 4
  • 8 to 10
  • 10 to 15
  • 15 to 20
Q.21

Raw materials are charged in the iron blast furnace using

  • bucket elevator
  • skip hoist
  • screw conveyor
  • none of these
Q.22

With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge

  • increases
  • decreases
  • remains constant
  • increases linearly
Q.23

Vibrating screens are used for handling large tonnages of materials. The vibrating motion is imparted to the screening surface by means of

  • electromagnets
  • cams or eccentric shafts
  • unblanced fly wheels
  • either (a), (b) or (c).
Q.24

Filter medium resistance is that offered by the

  • filter cloth.
  • embedded particles in the septum.
  • filter cloth and the embedded particle collectively.
  • none of these.
Q.25

The value of work index does not change materially from one equipment to another. If the value of work index determined for close circuit grinding is Wi, then the same for open circuit grinding will be

  • 0.5 Wi
  • Wi
  • 1.34 Wi
  • 3.34 Wi
Q.26

Maximum size reduction in a fluid energy mill is achieved by

  • compression
  • interparticle attrition
  • cutting
  • impact
Q.27

Dust collection efficiency of electrostatic precipitator can be as high as 99.9%. Maximum temperature and pressure of dust laden gas that can be cleaned in an electrostatic precipitator is respectively.

  • 200°C and 5 atm.
  • 1000°C and 10 atm.
  • 500°C and 50 atm.
  • 1000°C and 500 atm.
Q.28

A gravity decanter is meant for the separation of two __________ density.

  • immiscible liquids of different
  • miscible liquids of different
  • immiscible liquids of same
  • miscible liquids of same
Q.29

Which of the following minerals is not subjected to magnetic separation method?

  • Rutile
  • Galena
  • Chromite
  • Siderite
Q.30

In closed circuit grinding as compared to open circuit grinding, the

  • specific surface of product is more.
  • product has lesser size uniformity.
  • production rate at a given limiting size is lower.
  • operation is economical.
Q.31

The mechanism of size reduction by a hammer mill is by impact and attrition between the

  • grinding element & the housing.
  • feed particles.
  • both (a) and (b).
  • neither (a) nor (b).
Q.32

The grinding in a hammer crusher takes place due to the

  • attrition
  • impact
  • both (a) & (b)
  • neither (a) nor (b)
Q.33

A compressible cake has the

  • maximum porosity at the upstream side.
  • maximum porosity at the filter medium.
  • same porosity throughout the cake thickness.
  • none of these.
Q.34

For coarse reduction of hard solids, use

  • impact
  • attrition
  • compression
  • cutting
Q.35

In a size reduction crushing operation, feed size istomm. while the product size istomm. This is a case of the __________ crushing.

  • primary
  • secondary
  • fine
  • ultrafine
Q.36

In froth floatation, chemical agent added to cause air adherence is called

  • collector
  • frother
  • modifier
  • activator
Q.37

For grinding of cereals, grains, spices, pigments, saw dust, cork etc., the most extensively used size reduction equipment is a

  • Buhrstone mill
  • ball mill
  • crushing rolls
  • hammer mill
Q.38

Handling of ashes and similar materials can be done best by a __________ conveyor.

  • flight
  • drag or slat
  • belt
  • ribbon.
Q.39

Colloidal mills are used for __________ grinding.

  • coarse
  • intermediate
  • fine
  • ultrafine
Q.40

The porosity of a compressible cake is

  • minimum at the filter medium.
  • minimum at the upstream face.
  • maximum at the filter medium.
  • same throughout the thickness of cake.
Q.41

Which of the following parts of a jaw crusher is subjected to maximum wear and tear during its operation ?

  • Check plates
  • Jaw plates
  • Toggles
  • Crush shaft
Q.42

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

  • linear speed of the basket is doubled.
  • linear speed of the basket is halved.
  • centrifugal force is doubled.
  • capacity of centrifuge is increased.
Q.43

Pick out the wrong statement.

  • Hammer crushers operate by impact action.
  • Standard screens have circular opening.
  • With increase in mesh number of screens, their diameter in microns decreases.
  • 200 mesh screen has 200 openings per linear cm.
Q.44

For efficient grinding, ball mills must be operated

  • at a speed less than the critical speed.
  • at a speed more than the critical speed.
  • at a speed equal to the critical speed.
  • with minimum possible small balls.
Q.45

The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.

  • vacuum
  • sand
  • plate & frame
  • rotary
Q.46

Which of the following is not a revolving/tumbling mill used for size reduction?

  • Compartment mill
  • Pebble mill
  • Cage mill
  • Rod mill
Q.47

The inlet pressure in a constant rate filtration

  • increases continuously
  • decreases gradually
  • remains constant
  • none of these
Q.48

Pick out the correct statement.

  • Angle of repose is always greater than the angle of slide.
  • A hopper is a small bin with a sloping bottom.
  • A silo is a short height vessel of very large diameter used for the storage of high volatile matter coal.
  • Pine oil is used as a 'modifying agent' (for activating or depressing the adsorption of filming agents) in froth floatation process.
Q.49

A propeller agitator

  • produces mainly axial flow.
  • is used for mixing high viscosity pastes.
  • runs at very slow speed (2 rpm).
  • all (a), (b) and (c)
Q.50

Use of grinding aids results in the

  • enhanced production rate.
  • finer products.
  • both (a) & (b).
  • neither (a) nor (b).
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