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Mechanical Operations MCQ Questions & Answers

Mechanical Operations MCQs : This section focuses on the "Mechanical Operations". These Multiple Choice Questions (MCQs) should be practiced to improve the Mechanical Operations skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

Pine oil and cresylic acid are used as __________ in the froth floatation process.

A. Frother
B. Collector
C. Depressor
D. Conditioner

Question 2

During agitation of liquids, the

A. Froude number is independent for the curves between power number and Reynolds number in baffled system
B. Power number becomes independent of impellers Reynolds number at high Reynolds number, but is dependent on the geometry of the impeller
C. Froude number is used to account for the effect of surface (e.g., the centre vortex) on the power number
D. All of the above

Question 3

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

A. N°
B. N¹
C. N²
D. N³

Question 4

Sizing of very fine particles of the order of 5 to 10 microns is done by elutriation, which is a __________ operation.

A. Clarification
B. Sedimentation
C. Flocculation
D. Classification

Question 5

Fluid medium used in the classification technique of mineral beneficiation is

A. Air
B. Water
C. Both A & B
D. Neither A nor B

Question 6

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

A. Check plates
B. Jaw plates
C. Toggles
D. Crush shaft

Question 7

Screw conveyors are

A. Run at very high rpm
B. Suitable for sticky materials
C. Suitable for highly abrasive materials
D. All of the above

Question 8

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

A. Bag filter
B. Electrostatic precipitator
C. Cyclone separator
D. Wet scrubber

Question 9

Additives used for promoting the floccula-tion of particles is a/an

A. Electrolyte
B. Surface active agent
C. Both A & B
D. Neither A nor B

Question 10

Which of the following terminology is not used for size reduction of materials to fine sizes or powders?

A. Comminution
B. Dispersion
C. Pulverisation
D. Compression

Question 11

If dp is the equivalent diameter of a non-spherical particle, Vp its volume and sp its surface area, then its sphericity is Φs is defined by

A. Φs = 6 Vp/dp sp
B. Φs = Vp/dp sp
C. Φs = 6 dp Sp/Vp
D. Φs = dp Sp/Vp

Question 12

Shape factor for a cylinder whose length equals its diameter is

A. 1.5
B. 0.5
C. 1
D. 2

Question 13

Pick out the wrong statement.

A. For the compressible cake, voidage & the specific resistance of the cake can be assumed to be constant
B. Cake resistance is independent of the pressure drop
C. Crushing of explosive materials are done by employing drygrinding
D. Gyratory crusher is a coarse crusher

Question 14

During size reduction by a jaw crusher, the energy consumed decreases with the

A. Decreasing size of product at constant size of feed
B. Decreasing machine capacity
C. Increasing size of feed at constant reduction ratio
D. None of these

Question 15

For a non-spherical particle, the sphericity

A. is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle.
B. has the dimension of length.
C. is always less than 1.
D. is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle.

Question 16

A propeller agitator

A. Produces mainly axial flow
B. Is used for mixing high viscosity pastes
C. Runs at very slow speed (2 rpm)
D. All of the above

Question 17

Filtrate flow rate in case of a rotary drum vacuum filter (in which Rm < < Rc) is proportional to __________ and the cycle time (where, μ = filtrate viscosity Rm = filter medium resistance Rc = cake resistance ).

A. √μ
B. 1/√μ
C. 1/μ
D. 1/μ²

Question 18

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

A. Kozney-Karman
B. Hagen-Poiseulle's
C. Fanning's
D. Kremser

Question 19

Trommels employ __________ for screening of materials.

A. Fibrous cloth
B. Woven wire screen
C. Punched plate
D. None of these

Question 20

Pick out the wrong statement pertaining to the roll crushers.

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

Question 21

What is the usual value of angle of nip for crushing of ordinary rock in smooth steel crushing rolls?

A. 16°
B. 32°
C. 40°
D. 46°

Question 22

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

A. resins
B. gums
C. hard rubber
D. waxes

Question 23

Crushing efficiency is the ratio of the

A. Surface energy created by crushing to the energy absorbed by the solid
B. Energy absorbed by the solid to that fed to the machine
C. Energy fed to the machine to the surface energy created by crushing
D. Energy absorbed by the solid to the surface energy created by crushing

Question 24

Mechanical conveyors which push the material along an endless trough or tube are called scrappers. Which of the following conveying equipments comes under the category of 'scrappers'?

A. Bucket conveyor
B. Flight conveyor
C. Screw conveyor
D. Both B and C

Question 25

For a non-spherical particle, the sphericity

A. Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle
B. Has the dimension of length
C. Is always less than 1
D. Is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle

Question 26

All resistances during washing of cake

A. Increases
B. Decreases
C. Remain constant
D. None of these

Question 27

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 particle of a particular size is proportional to the square root of the surface to volume ratio of the product
C. Work required in crushing is proportional to the new surface created
D. For a given machine and feed, crushing efficiency is dependent on the size of the feed & product

Question 28

Filtration rate through a filter cake is proportional to (where, S = filtering surface R = specific cake resistance μ = viscosity of the filtrate)

A. S
B. 1/R
C. 1/μ
D. All of the above

Question 29

General mechanism of size reduction in intermediate and fine grinder is by

A. Cutting action
B. Compression
C. Compression and tearing
D. Impact and attrition

Question 30

In case of a hammer crusher, the

A. Feed may be highly abrasive (Moh's scale >5)
B. Minimum product size is 3 mm
C. Maximum feed size may be 50 mm
D. Rotor shaft carrying hammers can be vertical or horizontal

Question 31

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

A. Increases
B. Decreases
C. Remains constant
D. Increases linearly

Question 32

As per Taggart's formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where, L = Length of feed opening, cms S = Maximum width of discharge opening, cms )

A. LS
B. 93 LS
C. 250 LS
D. √LS

Question 33

The unit of filter medium resistance is

A. Cm⁻¹
B. Gm/cm⁻¹
C. Cm/gm⁻¹
D. Gm⁻¹

Question 34

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

A. Agitation
B. Filtration
C. Size enlargement
D. Humidification

Question 35

Colloid mills achieve size reduction mainly by

A. Impact
B. Attrition
C. Cutting
D. Compression

Question 36

Gelatinous solid (which plug the septum) can be filtered by a __________ filter.

A. Sparkler
B. Plate and frame
C. Vacuum leaf
D. Precoat

Question 37

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
C. 2.76
D. 0.66

Question 38

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

A. Agitation
B. Filtration
C. Size enlargement
D. Humidification

Question 39

Angle of nip of the crushing rolls does not depend upon the

A. Diameter of the rolls
B. Speed of the rolls
C. Product size
D. Feed size

Question 40

Reciprocal of sphericity is termed as the

A. Specific surface ratio
B. Shape factor
C. Sauter diameter
D. Surface area per unit mass

Question 41

Which of the following is a batch sedimentation equipment?

A. Dust catcher
B. Filter thickener
C. Dry cyclone separator
D. Rotary sprayer scrubber

Question 42

Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator?

A. Cresylic acid
B. Copper sulphate
C. Calcium carbonate
D. Sodium carbonate

Question 43

In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the __________ crushing.

A. Primary
B. Secondary
C. Fine
D. Ultrafine

Question 44

Gravity stamp mill is meant for the __________ crushing.

A. Primary
B. Intermediate
C. Fine
D. Ultrafine

Question 45

Pick out the wrong statement.

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

Question 46

200 mesh seive size corresponds to __________ microns.

A. 24
B. 74
C. 154
D. 200

Question 47

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

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

Question 48

In case of a hammer crusher,

A. Crushing takes place by impact breaking
B. Maximum acceptable feed size is 30 cms
C. Reduction ratio can be varied by adjusting the distance from cage to hammers
D. All of the above

Question 49

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

A. Compartment mill
B. Pebble mill
C. Cage mill
D. Rod mill

Question 50

For spheres, volume shape factor is given by

A. π(=A/D²)
B. 2π(=2A/D²)
C. π/6(=V/D³)
D. AD/V

Question 51

__________ are used for the separation of coarse particles from a slurry of fine particles.

A. Thickeners
B. Classifiers
C. Hydrocyclones
D. Decanters

Question 52

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

A. Specific surface of product is more
B. Product has lesser size uniformity
C. Production rate at a given limiting size is lower
D. Operation is economical

Question 53

The opening of a 200 mesh screen (Taylor series) is

A. 0.0074 cm
B. 0.0074 mm
C. 0.0047 cm
D. 74 mili-microns

Question 54

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

Question 55

What is the selectivity index, if the grade of tailings & concentrate is the same?

A. 0
B. ∞
C. 1
D. 0.5

Question 56

__________ centrifuge is normally used in sugar mills.

A. Tubular bowl
B. Disc-bowl
C. Suspended batch basket
D. Perforated horizontal basket continuous

Question 57

Ore concentration by jigging is based on the difference in the __________ of the particles.

A. Specific gravities
B. Wettability
C. Shape
D. None of these

Question 58

Pulverised coal passing through 200 mesh screen has a diameter of 0.074 mm (74 micron). The same passing through 50 mesh screen will have a dia of __________ mm.

A. 0.007
B. 0.3
C. 50
D. 0.014

Question 59

Paddle agitator

A. Is suitable for mixing low viscosity liquids
B. Produces axial flow
C. Moves at very high speed
D. None of these

Question 60

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

A. sedimentation
B. flocculation
C. dispersion
D. centrifugation

Question 61

Size reduction of fibrous materials like wood, asbestos, mica etc. is done by a disintegrator exemplified by the

A. Blake jaw crusher
B. Cage mill
C. Stamp mill
D. Bradford's breaker

Question 62

The work index in Bond's law for crushing of solids has the following dimensions

A. No units (dimensionless)
B. KWh/ton
C. KW/ton
D. KWh.m1/2/ton

Question 63

Pick out the correct statement.

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

Question 64

__________ is the most suitable for compounding rubber and plastic solids.

A. Banbery mixer
B. Pan mixer
C. Pug mill
D. Charge can mixer

Question 65

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)

A. m/ρ . Vp
B. m . ρ/Vp
C. m . Vp/ρ
D. Vp/m . ρ

Question 66

Energy consumed for crushing one ton of material ranges from __________ kWh.

A. 0.01 to 0.1
B. 0.5 to 1.5
C. 2 to 3.5
D. 4 to 5

Question 67

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

A. Dispersing gas in liquid
B. Blending of immiscible liquids
C. Dispersing immiscible liquid in form of emulsion
D. Suspending solid particles

Question 68

Separation of materials of the same density based on their sizes by using then-different rates of flow is called

A. Sorting
B. Sizing
C. Flocculation
D. Elutriation

Question 69

Sorting classifiers employing differential settling methods for separation of particles make use of the differences in their

A. Particle sizes
B. Densities
C. Terminal velocities
D. None of these

Question 70

Which of the following may prove unsuitable for filtering volatile liquids?

A. Pressure filter
B. Gravity filter
C. Centrifugal filter
D. Vacuum filter

Question 71

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

A. 2
B. √2
C. 1.5
D. √3

Question 72

Size reduction does not occur due to compression in case of

A. Rod mills
B. Gyratory crushers
C. Jaw crushers
D. Smooth roll crushers

Question 73

Which of the following grinding mills has the horizontally arranged rods as the grinding elements thereby delivering more uniform granular products with minimum fines?

A. Compartment mill
B. Rod mill
C. Pebble mill
D. Tube mill

Question 74

__________ conveyor is the most suitable for long distance transportation of cold, non-abrasive granular/irregular shape/fine materials.

A. Bucket
B. Belt
C. Screw
D. Apron

Question 75

Mass flow of granular solid (M) through a circular opening of dia, D follows

A. M ∝ √D
B. M ∝ D²
C. M ∝ D³
D. M ∝ D

Question 76

Separation of solid suspended in liquid into a supernatant clear liquid and a denser slurry employs a process termed as the

A. Coagulation
B. Flocculation
C. Sedimentation
D. Clarification

Question 77

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

A. Propeller agitator
B. Cone type agitator
C. Turbine agitator
D. Radial propeller agitator

Question 78

increasing the capacity of a screen __________ the screen effectiveness.

A. Decreases
B. Increases
C. Does not effect
D. None of these

Question 79

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

A. Trough washer
B. Baum jig washer
C. Spiral separator
D. Froth floatation

Question 80

Which of the following agitators having a large blade area, rotating at slow speed is used for mixing high viscosity liquids ( > 50000 centipoise)?

A. Propeller
B. Helical screw
C. Flat blade turbine
D. Curved blade turbine

Question 81

The value of 'angle of nip' is generally about

A. 16°
B. 32°
C. 52°
D. 64°

Question 82

__________ is used for producing a thick suspension from a thin slurry.

A. Cartridge filter
B. Rotary drum vacuum filter
C. Pressure filter thickener
D. Plate and frame filter press

Question 83

Equivalent diameter of a particle is the diameter of the sphere having the same

A. Ratio of surface to volume as the actual volume
B. Ratio of volume to surface as the particle
C. Volume as the particle
D. None of these

Question 84

Traces of liquid tar fog present in coke oven gas is separated using

A. Electrostatic precipitator
B. Cyclone separator
C. Strainer
D. None of these

Question 85

Size reduction of asbestos and mica is done by

A. Hammer mills
B. Rod mills
C. Gyratory crushers
D. Crushing rolls

Question 86

Specific surface area is the surface area of a unit __________ of materials.

A. Weight
B. Volume
C. Either A or B
D. Neither A nor B

Question 87

Highly viscous liquids & pastes are agitated by

A. propellers
B. turbine agitators
C. multiple blade paddles
D. none of these

Question 88

Filtration should be stopped in a filter press, if the

A. Cake becomes very dense
B. Liquor stops flowing out to the discharge
C. Filtration pressure rises suddenly
D. Both A & B

Question 89

To remove dirt from the flowing fluid, we use a

A. Coagulant
B. Gravity settler
C. Strains
D. Clarifier

Question 90

Which of the following achieves the least reduction ratio for a given feed size?

A. Jaw crusher
B. Roll crusher
C. Cone crusher
D. Gyratory crusher

Question 91

Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.

A. Viscosity
B. Thermal conductivity
C. Surface tension
D. Density

Question 92

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 of the above

Question 93

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

A. Feed rate
B. Rotor speed
C. Clearance between hammer & grinding plates
D. All of the above

Question 94

Screen efficiency is

A. Recovery/rejection
B. Recovery
C. Rejection
D. None of these

Question 95

The capacity of a gyratory crusher is __________ that of a jaw crusher with the same gape, handling the same feed & for the same product size range.

A. Same as
B. 2.5 times
C. 5 times
D. 10 times

Question 96

The most common filter aid is

A. Diatomaceous earth
B. Calcium silicate
C. Sodium carbonate
D. Silica gel

Question 97

Sphericity is the ratio of the surface area of a spherical particle having the same volume as the particle to the surface area of the particle. Which of the following has the maximum value of sphericity?

A. Sphere
B. Cube
C. Cylinder (L/D = 1)
D. Raschig rings

Question 98

__________ centrifuge is the most suitable for separation of non-friable crystals.

A. Tubular bowl
B. Disc-bowl
C. Perforated horizontal basket continuous
D. Suspended batch basket

Question 99

The capacity of a pneumatic conveying system depends upon the

A. Bulk density of materials
B. Pressure of the conveying air
C. Diameter of the conveying line
D. All of the above

Question 100

Pick out the correct statement:

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

Question 101

Ball mills and tube mills with flint or porcelain balls are used for size reduction of

A. asbestos
B. rubber
C. non-metallic ores
D. limestone

Question 102

Chance process is used for the

A. Cleaning of coal
B. Concentration of iron ore
C. Concentration of pyrites
D. Water treatment

Question 103

Pick out the correct statement.

A. Plastic chips are called non-cohesive solids
B. Kick's crushing law is, P/m = K . ln #####
C. Communition is a generic term for size enlargement operation
D. Energy required in kwh per ton of product, such that 80% of it passes through a 200 mesh screen, is called 'Work index'

Question 104

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

A. Gives less wear on chamber walls
B. Requires more energy
C. Increases capacity
D. Complicates handling of the product

Question 105

__________ mill is not a revolving mill.

A. Pebble
B. Compartment
C. Cage
D. Tube

Question 106

Which of the following is not a wet classifier?

A. Sharpies supercentrifuge
B. Hydrocyclones
C. Dorr Oliver rake classifier
D. None of these

Question 107

__________ baffles are provided in ball mills.

A. Horizontal
B. No
C. Only two
D. None of these

Question 108

Vacuum filter is most suitable for the

A. Removal of fines from liquid
B. Liquids having high vapour pressure
C. Liquids of very high viscosity
D. None of these

Question 109

In filtration, the use of 'filter aid' helps in

A. Reducing the filtration pressure
B. Accelerating the rate of filtration
C. Deplugging the filter medium
D. Enhancing the cake porosity in case of a dense impermeable cake

Question 110

Vertical transportation of materials can be done by a/an

A. Apron conveyor
B. Pneumatic conveyor
C. Bucket elevator
D. Both B & C

Question 111

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 of the above

Question 112

The equivalent diameter of channel of a constant non-circular cross-section of 3 cm by 6 cm will be __________ cms.

A. 20
B. 12
C. 8
D. 2

Question 113

The cake resistance increases steadily with the time of filtration in a plate and frame filter employing constant __________ filtration.

A. Rate
B. Pressure
C. Both A & B
D. Neither A nor B

Question 114

Which of the following is a continuous filter?

A. Plate and frame filter
B. Cartridge filter
C. Shell and leaf filter
D. None of these

Question 115

Gravity settling process is not involved in the working of a

A. hydrocyclone
B. classifier
C. dorr-thickener
D. sedimentation tank

Question 116

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

A. Immiscible liquids of different
B. Miscible liquids of different
C. Immiscible liquids of same
D. Miscible liquids of same

Question 117

The crushed material received for separation is called feed or

A. Tailing
B. Heading
C. Concentrate
D. Middling

Question 118

__________ is a cohesive solid.

A. Wheat
B. Sand
C. Wet clay
D. None of these

Question 119

The most efficient equipment for the removal of sub-micronic dust particles from blast furnace gas is the

A. Venturi atomiser
B. Gravity settling chamber
C. Electro-static precipitator
D. Cyclone separator

Question 120

Capacity of flight conveyor in tons/hr is given by (where, W & D = width and depth of flight respectively in metre V = speed of the conveyor, metre/second ρ = bulk density of material, kg/m³)

A. 3.6 W.D.V.ρ
B. 3.6 W.D.V.
C. 3.6 W.V.ρ
D. 3.6 D.V.ρ

Question 121

The material is crushed in a gyratory crusher by the action of

A. Impact
B. Compression
C. Attrition
D. Cutting

Question 122

For crushing of solids, the Rittinger's law states that the work required for crushing is proportional to

A. The new surface created
B. The size reduction ratio
C. The change in volume due to crushing
D. None of these

Question 123

Reciprocating screens are normally inclined at an angle of 5° with the horizontal and employ gyratory motion at feed end & reciprocating motion at the discharge end. They are not suitable for the screening of the

A. Light metal powder down upto 4 meshsize
B. Dry chemicals
C. Heavy tonnages of rocks or gravel
D. Powdered food & granular materials

Question 124

Size reduction mechanism used in Jaw crushers is

A. Attrition
B. Compression
C. Cutting
D. Impact

Question 125

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

A. Trough washer
B. Baum jig washer
C. Spiral separator
D. Froth floatation

Question 126

Balls for ball mills are never made of

A. forged/cast steel
B. lead
C. cast iron
D. alloy steel

Question 127

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.

A. speed
B. thickness
C. length
D. none of these

Question 128

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

Question 129

__________ mill is not used for grinding wheat into flour and for milling of cereals & other vegetable products.

A. Buhrstone
B. Roller
C. Attrition
D. Pebble

Question 130

Separation of isotopes is generally done using a/an __________ centrifuge.

A. Ultra
B. Disk-bowl
C. Both A & B
D. Neither A nor B

Question 131

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/μ: Reynold's number N is the impeller rotational speed, and D is the impeller diameter.

A. Po ∝ Re-1.0
B. Po ∝ Re0.0
C. Po ∝ Re0.5
D. Po ∝ Re1.0

Question 132

Which of the following is a fine crusher?

A. Blake jaw crusher
B. Gyratory crusher
C. Toothed roll crusher
D. Dodge jaw crusher

Question 133

Dispersion of a gas through liquid is done by using a

A. Sparger
B. Kneader
C. Masticator
D. None of these

Question 134

The process by which fine solids is removed from liquids is termed as

A. Decantation
B. Flocculation
C. Sedimentation
D. Classification

Question 135

For classification of potable (drinking) water, we use a __________ filter.

A. Gravity sand
B. Plate and frame
C. Vacuum leaf
D. Rotary vacuum

Question 136

Feed size of ≥ 25 cms can be accepted by

A. Ball mill
B. Rod mill
C. Fluid energy mill
D. Jaw crusher

Question 137

Equivalent diameter of a particle is the diameter of the sphere having the same

A. ratio of surface to volume as the actual volume.
B. ratio of volume to surface as the particle.
C. volume as the particle.
D. none of these.

Question 138

Ball mill is used for

A. Crushing
B. Coarse grinding
C. Fine grinding
D. Attrition

Question 139

Grinding efficiency of a ball mill is of the order of __________ percent.

A. 1-5
B. 40-50
C. 75-80
D. 90-95

Question 140

Pick out the wrong statement.

A. More commonly used jaw crusher between Dodge jaw crusher and Blake jaw crusher is the later one
B. There are only four methods namely compression, impact, attrition and cutting, which the size reduction equipments employ
C. Cutting machines mainly employ 'attrition' for size reduction of solids
D. Operating principles of Dodge and Blake jaw crushers are combined in the working of universal jaw crushers

Question 141

Size reduction of moulding powders, waxes, resins & gums are done in a __________ mill.

A. Cage
B. Hammer
C. Both A & B
D. Neither A nor B

Question 142

Pick out the wrong statement pertaining to the turbine agitator.

A. Recommended peripheral speed for the turbine agitator is 200-250 metres/minute
B. Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow
C. Generally, the diameter of the agitator is kept between l/3rd to l/6th of the tank diameter while the blade length is l/4th of agitator diameter (with central disc, it is l/8th of the agitator diamete
D. Turbine agitator should be located at a height not less than one agitator diameter length from the bottom. If the depth of liquid in the tank is more than twice the agitator diameter, two agitators sh

Question 143

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)

Question 144

Cake resistance is

A. Important in the beginning of filtration
B. Decreased with the time of filtration
C. Independent of pressure drop
D. None of these

Question 145

The inlet pressure in a constant rate filtration

A. Increases continuously
B. Decreases gradually
C. Remains constant
D. None of these

Question 146

Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for

A. British standard screens
B. German standard screens (DIN 1171) etc
C. American standard screens (ASTM and Tyler standard screens)
D. All of the above

Question 147

Dust laden air can be purified using a

A. Cyclone separator
B. Bag filter
C. Gravity settler
D. Tubular centrifuge

Question 148

Separation of materials into products based on the difference of their sizes is called

A. Sizing
B. Sorting
C. Classification
D. Flocculation

Question 149

Filter medium resistance is important during the __________ of filtration.

A. Early stages
B. Final stages
C. Entire process
D. None of these

Question 150

Which of the following is not used as a filter medium in case of corrosive liquids?

A. Nylon
B. Glass cloth
C. Metal cloth of monel or stainless steel
D. Cotton fabric

Question 151

__________ is defined as the geometric mean of the relative rejections and the relative recoveries of two minerals.

A. Separation efficiency
B. Selectivity index
C. Concentration ratio
D. None of these

Question 152

Which of the following can be most effectively used for clarification of lube oil and printing ink?

A. Sparkler filter
B. Precoat filter
C. Disc-bowl centrifuge
D. Sharpies supercentrifuge

Question 153

Weber number is significant and is concerned with the

A. Solid-liquid mixing
B. Liquid-liquid mixing
C. Dispersion of liquid in liquid
D. Suspension of solid in liquid

Question 154

The most suitable equipment for the transportation of 200 mesh size particles is a

A. Bucket elevator
B. Pneumatic conveyor
C. Screw conveyor
D. Belt conveyor

Question 155

In a roll crusher, both the rolls

A. Have the same diameter
B. Are rotated towards each other
C. Run either at the same or different speeds
D. All of the above

Question 156

Raw materials are charged in the iron blast furnace using

A. Bucket elevator
B. Skip hoist
C. Screw conveyor
D. None of these

Question 157

Removal of activated carbon from glycerine is done by

A. Plate and frame filter
B. Rotary vacuum filter
C. Batch basket centrifuge
D. None of these

Question 158

Carbon black is pulverised in a

A. Hammer crusher
B. Ball mill
C. Roll crusher
D. Gyratory crusher

Question 159

For transporting pasty material, one will use a/an

A. Apron conveyor
B. Belt conveyor
C. Screw colaveyor
D. Bucket elevator

Question 160

A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is

A. 0.1
B. 0.4
C. 0.6
D. None of these

Question 161

For the preliminary breaking of hard rock, we use a

A. Gyratory crusher
B. Ball mill
C. Tube mill
D. Squirrel-cage disintegrator

Question 162

Sulphuric acid mist is arrested by using a __________ scrubber.

A. packed wet
B. hollow wet
C. venturi
D. co-current

Question 163

Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )

A. D
B. 1/D
C. D2.5
D. 1/D2.5

Question 164

In screen analysis, the notation +5 mm/-10 mm means particles passing through

A. 10 mm screen and retained on 5 mm screen
B. 5 mm screen and retained on 10 mm screen
C. Both 5 mm and 10 mm screens
D. Neither 5 mm nor 10 mm screen

Question 165

For coarse reduction of hard solids, use

A. Impact
B. Attrition
C. Compression
D. Cutting

Question 166

For Indian standard (IS) screens, the mesh number is equal to its aperture size expressed to the nearest deca-micron (0.01 mm). Aperture width of IS screen of mesh number 50 will be approximately __________ microns.

A. 5
B. 50
C. 500
D. 5000

Question 167

Pick out the wrong statement.

A. Cummulative analysis for determining surface area is preferred over differential analysis, because of the assumption that "all particles in a simple fraction equal in size" is not needed for
B. A gate diagram is a plot of cummulative percent by weight undersize vs. the reciprocal of diameter, in which the area beneath the curve represents the surface
C. Capacity of crusher in choke feeding is increased
D. Rolling of pebbles/balls from top to bottom of the heap in tumbling mills is called 'cascading and throwing of the balls through the air to the toe of the heap is called 'cataracting'

Question 168

A straight line is obtained on plotting reciprocal of filtration rate vs. the volume of filtrate for __________ flow of filtrate.

A. Compressible cakes and laminar
B. Incompressible cake and laminar
C. Compressible cake and turbulent
D. Incompressible cake and turbulent

Question 169

__________ mills are termed as impactors.

A. Hammer
B. Cage
C. Rolling-compression
D. None of these

Question 170

In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow.

A. Plug
B. Turbulent
C. Laminar
D. None of these

Question 171

Pick out the wrong statement.

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

Question 172

In case of a ball mill,

A. Coarse feed requires a larger ball
B. Fine feed requires a larger ball
C. Operating speed should be more than the critical speed
D. None of these

Question 173

Helical screw agitator is used for

A. Mixing highly viscous pastes
B. Blending immiscible liquids
C. Mixing liquids at very high temperature (> 250 °C)
D. None of these

Question 174

Ultracentrifuges running at speeds upto 100000 rpm is normally used for the

A. Separation of isotopes based on their density or molecular weights difference
B. Concentration of rubber latex
C. Separation of cream from milk
D. Dewaxing of lubricating oil

Question 175

Cartridge filters are termed as 'edge' filters, because of the fact that the

A. Disks have very sharp edge
B. Solids are not deposited at the edge of the disk
C. Bulk of the solids are removed at the periphery of the disks
D. None of these

Question 176

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

Question 177

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

A. Micronizers
B. Agitated mills and fluid energy mills
C. Toothed roll crusher
D. Hammer mills with internal classification

Question 178

During the washing of cake

A. All the resistances are constant
B. Filter medium resistance increases
C. Filter medium resistance decreases
D. Cake resistance decreases

Question 179

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

A. 3
B. 30
C. 85
D. 25

Question 180

To get a fine talc powder from its granules, the equipment used is

A. Roller crusher
B. Ball mill
C. Jaw crusher
D. Gyratory crusher

Question 181

For separation of sugar solution from settled out mud, we use a __________ filter.

A. Sparkler
B. Plate and frame
C. Centrifugal
D. Rotary drum vaccum

Question 182

The constants (Kb, Kr and Kk) used in the laws of crushing (i.e., Bond's law, Rittinger's law and Kick's law) depend upon the

A. Feed material
B. Type of crushing machine
C. Both A & B
D. Neither A nor B

Question 183

The reduction ratio for grinders is defined as(where, Df and Dp are average diameters of feed and product respectively).

A. Df/Dp
B. Dp/Df
C. Df - Dp
D. None of these

Question 184

The speed of a rotary drum vacuum filter may be about __________ rpm.

A. 1
B. 50
C. 100
D. 500

Question 185

Sphericity of a cubical particle, when its equivalent diameter is taken as the height of the cube, is

A. 0.5
B. 1
C. √2
D. √3

Question 186

Fluid energy mill comes in the category of

A. Grinder
B. Crusher
C. Cutter
D. Ultrafine grinder

Question 187

Froth floatation is the most suitable for treating

A. iron ores
B. sulphide ores
C. quartzite
D. none of these

Question 188

Which of the following is the softest material?

A. Talc
B. Feldspar
C. Corundum
D. Calcite

Question 189

Which of the following is the most suitable filter for separation of abrasive solids suspended in a corrosive liquid?

A. Sand bed filter
B. Plate and frame filter press
C. Vacuum filter
D. Batch basket centrifuge

Question 190

The reduction ratio for fine grinders is

A. 5-10
B. 10-20
C. 20-40
D. As high as 100

Question 191

Rod mills employed for grinding

A. Employ a steel shell having L/D ratio of 1.5 to 3.0
B. Is useful for handling sticky materials
C. Employ steel rods of 2-12 cms diameter extending over full length of the mill
D. All of the above

Question 192

Which of the following conveyors cannot be recommended for transportation of abrasive materials?

A. Belt conveyor
B. Apron conveyor
C. Flight conveyor
D. Chain conveyor

Question 193

The specific surface of sherical particles is proportional to (where, Dp = diameter of particle).

A. D²p
B. Dp
C. 1/Dp
D. 1/D²p

Question 194

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

A. Size
B. Specific gravity
C. Terminal velocities in the same fluid & in the same field of force
D. None of these

Question 195

Optimum ratio of operating speed to critical speed of a trommel is

A. 0.33-0.45
B. 1.33-1.45
C. 0.5-2
D. 1.5-2.5

Question 196

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

A. Apron
B. Belt
C. Screw
D. Flight

Question 197

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

A. size.
B. specific gravity.
C. terminal velocities in the same fluid & in the same field of force.
D. none of these.

Question 198

For the transportation of ultrafine particles, the equipment used is a........conveyor.

A. Belt
B. Pneumatic
C. Screw
D. None of these

Question 199

Filtration capacity of a rotary drum vacuum filter depends upon the

A. Cake thickness
B. Characteristics of the feed slurry
C. Both A & B
D. Neither A nor B

Question 200

Colloidal mills are used for __________ grinding.

A. Coarse
B. Intermediate
C. Fine
D. Ultrafine

Question 201

In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.

A. Secondary
B. Fine
C. Primary
D. Ultrafine

Question 202

Which of the following is not used as filter aid?

A. Asbestos
B. Diatomaceous earth
C. Purified wood cellulose
D. Rice husk

Question 203

Short distance transportation of grain, gravel, sand, ash, asphalt etc. is done by using a __________ conveyor.

A. flight
B. slat or drag
C. ribbon
D. screw

Question 204

Ultrafine grinders operate principally by

A. Slow compression
B. Impact
C. Attrition
D. Cutting action

Question 205

Where the density difference of the two liquid phase to be separated is very small (as in milk cream separator), the most suitable separator is a

A. Disc bowl centrifuge
B. Sharpies supercentrifuge
C. Batch basket centrifuge
D. Sparkler filter

Question 206

Fick's law relates to

A. Energy consumption
B. Final particle size
C. Feed size
D. None of these

Question 207

Grindability of a material does not depend upon its

A. Elasticity
B. Hardness
C. Toughness
D. Size

Question 208

The distribution given by microscopic analysis of powder is

A. number
B. length
C. area
D. volume

Question 209

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

A. Flight
B. Drag or slat
C. Belt
D. Ribbon

Question 210

A cottrel precipitator makes use of the __________ for dusty air cleaning.

A. Electric spark
B. Corrona discharge
C. Alternating current
D. None of these

Question 211

Moisture can be removed from lubricating oil using

A. Tubular centrifuge
B. Clarifier
C. Sparkler filter
D. Vacuum leaf filter

Question 212

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 mill

Question 213

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

A. Toothed roll crusher
B. Gyratory crusher
C. Ball mill
D. Tube mill

Question 214

Sphericity of pulverised coal is

A. 1
B. <1
C. >1
D. ∞

Question 215

Sphericity of raschig ring (whose length and diameter are equal) is

A. >1
B. <1
C. 1
D. 2

Question 216

For a cyclone of diameter 0.2 m with a tangential velocity of 15 m/s at the wall, the separation factor is

A. 2250
B. 1125
C. 460
D. 230

Question 217

Pick out the wrong statement.

A. Recycled coarse material to the grinder by a classifier is termed as circulating load
B. Wear and tear in wet crushing is more than that in dry crushing of materials
C. Size enlargement (opposite of size reduction) is not a mechanical operation
D. A 'dust catcher' is simply an enlargement in a pipeline which permits the solids to settle down due to reduction in velocity of the dust laden gas

Question 218

Which of the following is a coarse crusher?

A. Smooth roll crusher
B. Toothed roll crusher
C. Gyratory crusher
D. Tube mill

Question 219

__________ conveyors are also called scrapers.

A. Apron
B. Screw
C. Helical flight
D. Both B & C

Question 220

Wet seiving is employed, when the product contains __________ materials.

A. Abrasive
B. Large quantity of very fine
C. Coarse
D. Non-sticky

Question 221

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

A. Vacuum
B. Sand
C. Plate & frame
D. Rotary

Question 222

Basic slag is not ground in

A. Jaw crushers
B. Ball mills
C. Compartment mills
D. Tube mills

Question 223

Sedimentation on commercial scale occurs in

A. Classifiers
B. Thickeners
C. Rotary drum filters
D. Cyclones

Question 224

Gummy & sticky materials like molasses, sugar etc. are best transported/handled by using a __________ conveyor.

A. Drag
B. Ribbon
C. Screw
D. Slat

Question 225

Apron conveyors are used for

A. Heavy loads & short runs
B. Small loads & long runs
C. Heavy loads & long runs
D. None of these

Question 226

Dry powdery solid materials are transported by a __________ conveyor.

A. Belt
B. Bucket
C. Screw
D. None of these

Question 227

Toothed roll crushers achieve size reduction by

A. Tearing (shear) and compression
B. Impact and attrition
C. Both A & B
D. Neither A nor B

Question 228

Which of the following size reduction equipments employs mainly attrition for ultrafine grinding?

A. Jet mills
B. Fluid energy mill
C. Micronizer
D. All of the above

Question 229

In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is

A. 4
B. 1-4
C. 1
D. 1-2

Question 230

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

Question 231

Sauter mean diameter is the same as the __________ mean diameter.

A. Mass
B. Arithmetic
C. Volume-surface
D. Geometric

Question 232

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

A. 35
B. 50
C. 70
D. 85

Question 233

Pick out the wrong statement.

A. Recycled coarse material to the grinder by a classifier is termed as circulating load.
B. Wear and tear in wet crushing is more than that in dry crushing of materials.
C. Size enlargement (opposite of size reduction) is not a mechanical operation.
D. A 'dust catcher' is simply an enlargement in a pipeline which permits the solids to settle down due to reduction in velocity of the dust laden gas.

Question 234

Ultra centrifuges are used for the separation of __________ solid particles.

A. Coarse
B. Fine
C. Colloidal
D. Dissolved

Question 235

For efficient grinding, ball mills must be operated

A. At a speed less than the critical speed
B. At a speed more than the critical speed
C. At a speed equal to the critical speed
D. With minimum possible small balls

Question 236

Filter medium resistance is that offered by the

A. Filter cloth
B. Embedded particles in the septum
C. Filter cloth and the embedded particle collectively
D. None of these

Question 237

Vibrating screens have capacity in the range of __________ tons/ft² .mm mesh size.

A. 0.2 to 0.8
B. 5 to 25
C. 50 to 100
D. 100 to 250

Question 238

The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle).

A. 6/D.p
B. 2/D.p
C. 4/D.p
D. 12/D.p

Question 239

Which of the following crushing laws is most accurately applicable to the fine grinding of materials ?

A. Bond's crushing law
B. Kick's law
C. Rittinger's law
D. None of these

Question 240

Tube mill compared to ball mill

A. Produces finer products
B. Is long in comparison with its diameter
C. Uses smaller balls
D. All of the above

Question 241

Ribbon blenders are exclusively meant for

A. Blending miscible liquids
B. Non-flowing powder and thin pastes
C. Bath mixing
D. Continuous mixing

Question 242

Which of the following is a pressure filter?

A. Leaf filter (Moore filter)
B. Plate and flame filter
C. Rotary drum filter
D. Sand filter

Question 243

A sand mixture was screened through a standard 10-mesh screen. The mass fraction of the oversize material in feed, overflow and underflow were found to be 0.38, 0.79 and 0.22 respectively. The screen effectiveness based on the oversize is

A. 0.5
B. 0.58
C. 0.68
D. 0.62

Question 244

The most suitable equipment used to devulcanise rubber scrap and to make water dispersion & rubber solution is a

A. Boundary mixer
B. Propeller agitator
C. Sharpies centrifuge
D. None of these

Question 245

For raschig rings, the sphericity is

A. 0.5
B. 1
C. <1
D. √3

Question 246

Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the __________ filtration.

A. Constant rate
B. Varying pressure
C. Varying rate
D. Constant pressure

Question 247

Wheat is ground into flour in a

A. Hammer crusher
B. Roller crusher
C. Impact mill
D. Fluid energy mill

Question 248

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 of the above

Question 249

Bucket elevators are not suitable for the vertical lifting of __________ materials.

A. Fine (e.g. - 200 mesh size coal)
B. Sticky (e.g. clay paste)
C. Small lumpy (e.g. grains and sand)
D. Free flowing

Question 250

Which of the follwoing mechanical conveyors does not come under the division 'scrapers'?

A. Ribbon conveyor
B. Flight conveyor
C. Bucket elevators
D. Drag conveyor

Question 251

Shell and leaf filter as compared to plate and frame filter

A. Entails less labor cost
B. Facilitates filtration under higher pressure
C. Provides more effective washing
D. All of the above

Question 252

For a sphere falling in the constant drag co-efficient regime, its terminal velocity depends on its diameter (d) as

A. D
B. √d
C. D²
D. 1/d

Question 253

__________ mills fall in the category of tumbling mills,

A. Ball and pebble
B. Rod and tube
C. Compartment
D. All of the above

Question 254

Cement clinker is reduced to fine size by a

A. Roll crusher
B. Ball mill
C. Tube mill
D. Hammer mill

Question 255

The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)

A. ∝ ΔP
B. ∝ 1/ ΔP
C. ∝ √ΔP
D. Independent of ΔP

Question 256

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 energy mill
C. Fluid energy mill, Jaw crusher, Ball mill
D. Fluid energy mill, Ball mill, Jaw crusher

Question 257

The process opposite to 'dispersion' is termed as the

A. Flocculation
B. Sedimentation
C. Filtration
D. None of these

Question 258

200 mesh screen means 200 openings per

A. Cm²
B. Cm
C. Inch
D. Inch²

Question 259

Introduction of slurry in a plate and frame filter press is done through a plate in each frame. The plate of this filter has a __________ surface.

A. Plane
B. Curved
C. Ribbed
D. Either A or B

Question 260

Energy requirement (per unit mass of material crushed/ground) is highest for

A. Jaw crusher
B. Rod mill
C. Ball mill
D. Fluid energy mill

Question 261

During washing of filter at the end of constant pressure filtration, the rate of washing equals the rate of filtration

A. At time zero
B. At the end of filtration
C. When half the filtrate has been obtained
D. At the end of filtration, but decreases with time subsequently

Question 262

The maximum slope of a belt conveyor can be

A. 15°
B. 30°
C. 45°
D. 60°

Question 263

A __________ employs a set of screen across a flow channel for the separation of dirt/rust from a flowing liquid stream.

A. Thickener
B. Classifier
C. Strainer
D. Clarifier

Question 264

Supporting legs of a plate and frame filter is normally made of

A. Stainless steel
B. Cast iron
C. High speed steel
D. Wooden plank

Question 265

Pick out the material having minimum Rittinger's number.

A. Calcite
B. Pyrite
C. Quartz
D. Galena

Question 266

In the cyclone separator used for separation of dust from dust laden gas, the gas

A. Enters the cyclone from the top
B. Is admitted tangentially at high velocity
C. Develops a helical motion inside the chamber
D. Both B and C

Question 267

Which of the following is a pressure filter ?

A. Leaf filter (Moore filter).
B. Plate and flame filter.
C. Rotary drum filter.
D. Sand filter.

Question 268

Which of the following gives the crushing energy required to create new surface ?

A. Taggarts rule
B. Fick's law
C. Rittinger's law
D. None of these

Question 269

Particle size range in which dust catcher (gravity settling chamber) works most effectively and efficiently is __________ microns.

A. < 5
B. 10 to 25
C. < 74
D. > 1000

Question 270

A compressible cake has the

A. Maximum porosity at the upstream side
B. Maximum porosity at the filter medium
C. Same porosity throughout the cake thickness
D. None of these

Question 271

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

Question 272

To get ultrafine particles, the equipment used is a

A. Ball mill
B. Rod mill
C. Hammer crusher
D. Fluid energy mill

Question 273

In paint industries, blending of light paste is done by using a

A. Masticator
B. Charge can mixer
C. Kneader
D. None of these

Question 274

The porosity of a compressible cake is

A. Minimum at the filter medium
B. Minimum at the upstream face
C. Maximum at the filter medium
D. Same throughout the thickness of cake

Question 275

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 ?

A. μ > tan α
B. μ ≥ tan α
C. μ > tan 2α
D. μ ≤ tan α

Question 276

The ratio of the area of openings in one screen (Taylor series) to that of the openings in the next smaller screen is

A. 1.5
B. 1
C. ?2
D. None of these

Question 277

Which of the following is not an industrial screening equipment?

A. Sharpies centrifuge
B. Vibrating screen
C. Grizzly
D. Trommel

Question 278

Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)

A. 0.5 D
B. D
C. 1.5 D
D. 2 D

Question 279

Electrical energy consumed by a jaw crusher is not a function of the

A. Average feed size
B. Average product size
C. Machine capacity
D. None of these

Question 280

Pick out the wrong statement:

A. Magnetic separation method can be employed to treat both dry & wet ores
B. Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size
C. Gyratory crusher is used for coarse crushing
D. Screens are of stationary, moving and vibratory types

Question 281

Gold ore concentration is mostly done using

A. Jigging
B. Tabling
C. Froth floatation
D. Elutriation

Question 282

Which of the following must be stored in silos and not in open yard?

A. Coke breeze
B. High V.M. bituminous coal
C. Sand
D. None of these

Question 283

Cyclones are used primarily for separating

A. Solids
B. Solids from fluids
C. Liquids
D. Solids from solids

Question 284

Molten ammonium nitrate is mixed with ground limestone in fertilizer plant in a

A. Pug mill
B. Mixer-extruder
C. Banbury mixer
D. Muller mixer

Question 285

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

Question 286

Which of the following is not used as a surface active agent in a flocculation operation?

A. Sodium silicate
B. Quartz
C. Lime
D. Alumina

Question 287

Fibrous material is broken by a

A. Rollcrusher
B. Squirrel-cage disintegrator
C. Ball mill
D. Tube mill

Question 288

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

Question 289

Use of 'grinding aids' is done in __________ grinding.

A. Dry
B. Wet
C. Ultrafine
D. Intermediate

Question 290

Choke crushing (in case of a Jaw crusher) compared to free crushing

A. Results in increased capacity
B. Consumes less power
C. Consumes more power
D. Both A and C

Question 291

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

A. Grinding element & the housing
B. Feed particles
C. Both A & B
D. Neither A nor B

Question 292

For spheres, the specific surface shape factor is given by

A. AD/V
B. D/V
C. A/V
D. √(AD/V)

Question 293

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

A. Hanger
B. Check plates
C. Toggles
D. Pitman

Question 294

The energy required per unit mass to grind limestone particles of very large size to 100 μm is 12.7 kWh/ton. An estimate (using Bond's law) of the energy to grind the particles from a very large size to 50 μrn is

A. 6.35 kWh/ton
B. 9.0 kWh/ton
C. 18 kWh/ton
D. 25.4 kWh/ton

Question 295

The unit of specific cake resistance is

A. Gm/cm²
B. Cm/gm
C. Cm/gm²
D. Gm/gm

Question 296

For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid?

A. Kozney-Karman equation
B. Leva
C. Blake-Plummer equation
D. None of these

Question 297

For benefication of iron ore, the most commonly used method is

A. Flocculation
B. Froth floatation
C. Jigging & tabling
D. None of these

Question 298

__________ mill is normally used for grinding of talc.

A. Tube
B. Compartment
C. Ring-roll
D. Pebble

Question 299

Xanthates are used in the froth floatation process as a/an

A. Conditioner
B. Frother
C. Collector
D. Activator

Question 300

Screen capacity is not a function of

A. Its openings size
B. Screening mechanism
C. Screening surface
D. Atmospheric humidity

Question 301

Addition of filter aid to the slurry before filtration is done to ...... of the cake.

A. Increase the porosity
B. Increase the compressibility co-efficient
C. Decrease the porosity
D. Decrease the compressibility co-efficient

Question 302

__________ mills are termed as disintegrators.

A. Cage
B. Compartment
C. Pebble
D. All of the above

Question 303

Maximum size reduction in a fluid energy mill is achieved by

A. Compression
B. Interparticle attrition
C. Cutting
D. Impact

Question 304

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

A. Propeller agitator
B. Cone type agitator
C. Turbine agitator
D. Radial propeller agitator

Question 305

200 mesh screen means 200 openings per

A. cm2
B. cm
C. inch
D. inch2

Question 306

With increase in the capacity of screens, the screen effectiveness

A. Remains unchanged
B. Increases
C. Decreases
D. Decreases exponentially

Question 307

Vacuum is applied in __________ zone, in case of a general type continuous rotary drum vacuum filter.

A. Filtering
B. Washing
C. Drying
D. All of the above

Question 308

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

A. clarification
B. classification
C. elutriation
D. sedimentation

Question 309

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, V =πN.D where, N = speed of the rolls in rotation per second (rps) D = diameter of rolls, m)

A. 3.6 V.W.Dr.ρ
B. 3.6 V.W. ρ
C. 3.6 W.Dr.ρ
D. 3.6 V.W.Dr/ρ

Question 310

In constant pressure filtration,

A. Resistance decreases with time
B. Rate of filtration is constant
C. Rate of filtration increases with time
D. Rate of filtration decreases with time

Question 311

According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively).

A. (S/V)p
B. √(S/V)p
C. (S/V)²p
D. (S/V)f

Question 312

Screen capacity is expressed in terms of

A. Tons/hr
B. Tons/ft²
C. Both A & B
D. Tons/hr-ft²

Question 313

Size reduction of ice and gypsum can be accomplished suitably by a __________ crusher.

A. Blake jaw
B. Toothed roll
C. Gyratory
D. None of these

Question 314

Which of the following is the hardest material?

A. Calcite
B. Quartz
C. Corundum
D. Gypsum

Question 315

Which of the following screens has the maximum capacity?

A. Grizzlies
B. Trommels
C. Shaking screen
D. Vibrating screen

Question 316

Length/diameter ratio of a ball mill is

A. 1.5
B. 1
C. < 1
D. > 1

Question 317

A filter press is

A. A batch filter
B. Not suitable, if the liquid is the main product
C. Having prohibitively high maintenance cost
D. Not suitable for wide range of materials under varying operating conditions of cake thickness and pressure

Question 318

The study on washability of coal is done by using the __________ technique.

A. Tabling
B. Elutriation
C. Heavy media separation
D. None of these

Question 319

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

Question 320

Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called

A. Classification
B. Froth floatation
C. Thickening
D. Clarification

Question 321

Mixing of light fine powder such as insecticides is done by

A. Banbery mixer
B. Pug mill
C. Impact wheels
D. Kneader

Question 322

A. __________ mill is a revolving mill divided into two or more sections by perforated partitions in which preliminary grinding takes place at one end and the finishing grinding at the discharge end.

A. Compartment
B. Tube
C. Rod
D. Pebble

Question 323

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

A. Swirling
B. Vortexing
C. Both A & B
D. Neither A nor B

Question 324

Float and sink test determines the possibility of cleaning of coal by a process based on the

A. Gravity separation
B. Wettability
C. Particle shape
D. None of these

Question 325

Maximum size reduction in a ball mill is done by the, __________ action.

A. Attrition
B. Compression
C. Impact
D. Cutting

Question 326

Width and speed of a conveyor belt depends upon the __________ of the material.

A. Lump size
B. Bulk density
C. Both A & B
D. Neither A nor B

Question 327

__________ 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

Question 328

In bag filters, filter fabrics are never made of

A. Metallic wire woven mesh
B. Polyester fibres
C. Cotton fibres
D. Nylon fibres

Question 329

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

Question 330

Solid particles of different densities are separated by

A. Filters
B. Thickness
C. Cyclones
D. Sorting classifier

Question 331

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

A. Panning
B. Spiralling
C. Tabling
D. None of these

Question 332

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

Question 333

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

Question 334

Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?

A. Parabola
B. Straight line
C. Hyperbola
D. Exponential curve

Question 335

Driving force in case of filtration by a centrifuge is the

A. Speed of the centrifuge
B. Centrifugal pressure exerted by the liquid
C. Narrow diameter of the vessel
D. Formation of highly porous cake

Question 336

The specific cake resistance for compressible sludges is a function of the pressure drop

A. Over cake
B. Over medium
C. Overall
D. None of these

Question 337

Traces of solids are removed from, liquid in a

A. Classifier
B. Clarifier
C. Sparkler filter
D. Rotary vacuum filter

Question 338

Tabling process used for separating two materials of different densities by passing the dilute pulp over a table/deck, which is inclined from the horizontal surface at an angle of about

A. 1 to 2°
B. 2 to 5°
C. 5 to 10°
D. 10 to 15°

Question 339

The term 'angle of nip' is concerned with the operation of the __________ crushers.

A. Jaw
B. Roll
C. Gyratory
D. None of these

Question 340

Grinding characteristic of a material is given by its

A. HGI
B. Angle of repose
C. Shatter index
D. Abrasion index

Question 341

Separation of a suspension or slurry into a supernatant clear liquid (free from particles) and a thick sludge containing a high concentration of solid is called

A. Classification
B. Sedimentation
C. Clarification
D. Decantation

Question 342

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

A. Open sand
B. Plate and frame
C. Vacuum leaf
D. Sparkler

Question 343

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

A. Apron conveyor
B. Belt conveyor
C. Screw conveyor
D. Pneumatic conveyor

Question 344

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

A. Linear speed of the basket is doubled
B. Linear speed of the basket is halved
C. Centrifugal force is doubled
D. Capacity of centrifuge is increased

Question 345

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

A. bronze
B. stainless steel
C. flint or porcelain
D. concrete

Question 346

Rittinger's number designates the new surface created per unit mechanical energy absorbed by the material being crushed. Larger value of Rittinger's number of a material indicates its

A. Easier grindability
B. Poor grindability
C. High power consumption in grinding
D. None of these

Question 347

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

A. Electromagnets
B. Cams or eccentric shafts
C. Unblanced fly wheels
D. Either A, B or C

Question 348

The sphericity of a solid particle of cubical shape is

A. π
B. (π/6)1/3
C. (π/6)1/2
D. π/3

Question 349

For a turbine agitated and baffled tank, operating at low Reynold's number (based on impeller diameter), the power number (Np) varies with NRe as

A. Np ∝ NRe
B. Np ∝ √NRe
C. Np → constant
D. Np ∝ 1/NRe

Question 350

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

A. Added to the feed slurry
B. Precoated on the filter medium prior to filtration
C. Separated from the cake by dissolving solids or by burning it off
D. All of the above

Question 351

Trommels separate a mixture of particles depending on their

A. Size
B. Density
C. Wettability
D. Electrical & magnetic properties

Question 352

In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of __________ crushing.

A. Primary
B. Secondary
C. Fine
D. Ultrafine

Question 353

Energy consumption in a crusher decreases with increase in the

A. Size of the product (at constant feed size)
B. Capacity of the crushing machine
C. Size of feed (at constant reduction ratio)
D. All of the above

Question 354

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

A. State or manner of application of the crushing force
B. Ultimate strength of the material
C. Elastic constant of the material
D. All of the above

Question 355

The filter medium resistance is controlled by

A. Pressure drop alone
B. Flow rate alone
C. Both pressure drop and flow rate
D. Cake thickness

Question 356

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 grindng of large particles in un-baffed mills

Question 357

Tabular bowl centrifuges as compared to disk bowl centrifuges

A. Operate at higher speed
B. Employ bowl of larger diameter
C. Can not be operated under pressure/vacuum
D. Can't be used for separation of fine suspended solids from a liquid

Question 358

Which of the following is not a cutting machine?

A. Dicers
B. Knife cutters
C. Slitters
D. Tube mills

Question 359

For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the __________ filter.

A. Plate & frame
B. Shell & leaf
C. Sand
D. Rotary vacuum

Question 360

Filtration rate does not depend upon the

A. Pressure drop & area of filtering surface
B. Resistance of the cake & the septum
C. Properties of the cake & the filtrate
D. None of these

Question 361

Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the

A. Density separation
B. Differential wettability
C. Size
D. Volatile matter content

Question 362

Separation of solid particles based on their densities is called

A. Sizing
B. Sorting
C. Clarification
D. Dispersion

Question 363

Compressibility co-efficient for an absolutely compressible cake is

A. 0
B. 1
C. 0 to 1
D. ∞

Question 364

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

A. Collector
B. Frother
C. Modifier
D. Activator

Question 365

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

A. 1 - 2
B. 15 - 20
C. 40 - 50
D. 60 - 75

Question 366

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.

A. impact
B. roll
C. vibratory
D. none of these

Question 367

According to Taggart's rule for selecting between a gyratory crusher and a jaw crusher; the later should be used, if the hourly tonnage to be crushed divided by the square of the gape expressed in cm is less than

A. 0.00184
B. 0.0184
C. 0.184
D. 1.84

Question 368

Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.

A. 1
B. 0.5
C. 1.34
D. 4.34

Question 369

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

A. Smallest
B. Largest
C. Either A or B
D. Neither A nor B

Question 370

A screen is said to be blinded, when the

A. Oversizes are present in undersize fraction
B. Undersizes are retained in oversize fraction
C. Screen is plugged with solid particles
D. Screen capacity is abruptly increased

Question 371

As particle size is reduced

A. Screening becomes progressively more difficult
B. Screening becomes progressively easier
C. Capacity and effectiveness of the screen is increased
D. None of these

Question 372

Size measurement of ultrafine particles can be best expressed in terms of

A. Centimetre
B. Screen size
C. Micron
D. Surface area per unit mass

Question 373

Reduction ratio of crushers is the

A. Ratio of feed opening to discharge opening
B. Ratio of discharge opening to feed opening
C. Determining factor for minimum dia of the feed and the product
D. None of these

Question 374

Pick out the wrong statement pertaining to the roll crushers.

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

Question 375

In case of a hammer crusher,

A. crushing takes place by impact breaking.
B. maximum acceptable feed size is 30 cms.
C. reduction ratio can be varied by adjusting the distance from cage to hammers.
D. all (a), (b) and (c).

Question 376

Moore filter is a __________ filter.

A. Leaf
B. Press
C. Rotary
D. Sand

Question 377

The resistance offered by the filter used in a bag filter is proportional to (where, c = dust concentration, and s = particle size )

A. C/s
B. S/c
C. S . c
D. 1/s . c

Question 378

Filter aid is used to

A. increase the rate of filtration.
B. decrease the pressure drop.
C. increase the porosity of the cake.
D. act as a support base for the septum.

Question 379

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

A. Reduction ratio
B. Differential roll speed
C. Both A & B
D. Neither A nor B

Question 380

The main size reduction operation in ultrafine grinders is

A. cutting
B. attrition
C. compression
D. impact

Question 381

Bond crushing law

A. Calls for relatively less energy for the smaller product particles, than does the Rittinger law
B. Is less realistic in estimating the power requirements of commercial crushers
C. 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
D. States that the work required for the crushing is proportional to the new surface created

Question 382

Filter aid is used to

A. Increase the rate of filtration
B. Decrease the pressure drop
C. Increase the porosity of the cake
D. Act as a support base for the septum

Question 383

Limestone is normally crushed in a

A. Roll crusher
B. Hammer crusher
C. Ball mill
D. Tube mill

Question 384

Stamp mills are generally used for crushing

A. Iron ores
B. Gold ores
C. Talc
D. Diamond

Question 385

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

Question 386

Which one is a filter aid?

A. Convas fabric
B. Diatomaceous earth
C. Calcined lime
D. None of these

Question 387

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

A. Banbery mixer
B. Pug mill
C. Muller-mixer
D. None of these

Question 388

During filtration operation, the filtrate encounters the resistance of the

A. Filter medium
B. Cake
C. Channel carrying the slurry to the upstream side of the cake and filtrate away from the filter medium
D. All of the above

Question 389

Screen capacity is proportional to (where, S = screen aperture)

A. S
B. 1/S
C. S²
D. √S

Question 390

To remove very small amount of tiny solid impurities from liquid, we use a

A. Pressure filter
B. Vacuum filter
C. Centrifugal filter
D. Coagulant

Question 391

Capacity (in tons/hr) of jaw/gyratory crusher is equal to (where, L = length of the receiving opening, cm S = greater width of the discharge opening, cm)

A. 0.01 L.S
B. 0.087 L.S
C. L.S
D. L.S/0.087

Question 392

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

A. Square root of the velocity
B. Square of the viscosity
C. Filtration time only
D. Washing time only

Question 393

With increase in drum speed, in a rotary drum filter, the filtration rate

A. Increases
B. Increases linearly
C. Decreases
D. Is not affected

Question 394

Soft & non-abrasive materials can be made into fines by

A. Attrition
B. Compression
C. Cutting
D. None of these

Question 395

A widely used size reduction equipment for __________ is Bradford breaker.

A. Talc
B. Coal
C. Iron core
D. Wheat

Question 396

Mixer used for rubber compounding is

A. Mixer-extruder
B. Banbury internal mixer
C. Muller mixer
D. Pug mill

Question 397

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

A. square root of the velocity.
B. square of the viscosity.
C. filtration time only.
D. washing time only.

Question 398

The sphericity of a cylinder of 1 mm diameter and length 3 mm is

A. 0.9
B. 0.78
C. 0.6
D. 0.5

Question 399

A fluid energy mill is used for

A. Cutting
B. Grinding
C. Ultra grinding
D. Crushing

Question 400

Use of grinding aids results in the

A. Enhanced production rate
B. Finer products
C. Both A & B
D. Neither A nor B

Question 401

Which of the following comes in the category of primary crusher for hard and tough stone?

A. Jaw crusher
B. Cone crusher
C. Gyratory crusher
D. None of these

Question 402

A belt conveyor used for the transportation of materials can

A. Run upto 1 km
B. Travel at a speed upto 300 metres/minute
C. Handle materials upto 5000 tons/hr
D. All of the above

Question 403

The capacity of a pneumatic conveying system depends upon the

A. bulk density of materials.
B. pressure of the conveying air.
C. diameter of the conveying line.
D. all (a), (b) and (c).

Question 404

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

A. 0.5 Wi
B. Wi
C. 1.34 Wi
D. 3.34 Wi

Question 405

In classification, particles are said to be equal settling, if they have the same terminal velocities in the

A. Different fluids
B. Same fluid
C. Same field of force
D. Both B and C

Question 406

Tabular bowl centrifuges as compared to disk bowl centrifuges

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

Question 407

Work index is defined as the

A. Gross energy (kWh/ton of feed) needed to reduce very large feed to such a size that 80% of the product passes through a 100 micron screen
B. Energy needed to crush one tonne of feed to 200 microns
C. Energy (kWh/ton of feed) needed to crush small feed to such a size that 80% of the product passes a 200 mesh screen
D. Energy needed to crush one ton of feed to 100 microns

Question 408

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

A. Tumbler
B. Banbery
C. Muller
D. Rubbon blender

Question 409

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

Question 410

In coal washeries, three products namely the valuable product (i.e. clean/washed coal), discarded product (i.e. mineral matter) and an additional concentrated product called __________ is produced.

A. Concentrate
B. Tailing
C. Middling
D. None of these

Question 411

To produce talcum powder, use

A. Ball mill
B. Hammer mill
C. Jet mill
D. Pin mill

Question 412

Which of the following is not a non-metalliferous mineral?

A. Calcite
B. Fluorspar
C. Quartz
D. Cassiterrite

Question 413

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

A. trommel
B. grizzly
C. shaking screen
D. vibrating screen

Question 414

Which is a secondary crusher for a hard & tough stone?

A. Jaw crusher
B. Cone crusher
C. Impact crusher
D. Toothed roll crusher

Question 415

In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is

A. 4
B. 01-Apr
C. 1
D. 01-Feb

Question 416

__________ are mixed using ribbon blenders.

A. Lumpy solids and low viscosity liquids
B. Dry powders
C. High viscosity liquids
D. Thick pastes

Question 417

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.

A. 200°C and 5 atm
B. 1000°C and 10 atm
C. 500°C and 50 atm
D. 1000°C and 500 atm

Question 418

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

A. Belt conveyor
B. Bucket elevator
C. Screw conveyor
D. Apron conveyor

Question 419

Diatomaceous earth is a/an

A. explosive
B. filter aid
C. filter medium
D. catalyst

Question 420

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

Question 421

Cumulative analysis for determining surface is more precise than differential analysis, because of the

A. Assumption that all particles in a single fraction are equal in size
B. Fact that screening is more effective
C. Assumption that all particles in a single fraction are equal in size, is not needed
D. None of these

Question 422

Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are

A. Carbonates
B. Sulphates
C. Silicates & phosphates
D. Bi-carbonates

Question 423

Kick's law assumes that the energy required for size reduction is proportional to the logarithm of the ratio between the initial and the final diameters. The unit of Kick's constant is

A. KW. sec/kg
B. KWh/kg
C. KWh/sec. kg
D. Kg/sec

Question 424

The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area, m² V = rising velocity of fluid, m/sec.S = percentage of solids in the suspension by volume.ρ = density of solids, kg/m³)

A. 3.6 AVS.ρ
B. 3.6 A.V.ρ
C. 3.6 A.S. ρ
D. 3.6 AVS/ρ

Question 425

Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle).

A. 6.V/D.S
B. V/6D.S
C. D.S/V
D. V/D.S

Question 426

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

A. Rutile
B. Galena
C. Chromite
D. Siderite

Question 427

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

A. >10
B. <10
C. >100
D. <100

Question 428

During agitation of liquids, power consumption during laminar flow is not proportional to the

A. Density of the liquid
B. Viscosity of the liquid
C. Cube of impeller diameters
D. Square of rotational speed

Question 429

Metallic wire mesh is used as a filtering medium for the separation of dust from dust laden gas in case of a/an

A. Air filter
B. Bag filter
C. Venturi scrubber
D. Hydrocyclones

Question 430

Gizzlies are used for separating __________ solids.

A. Coarse
B. Fine
C. Any size
D. None of these

Question 431

Pick out the wrong statement.

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

Question 432

Mesh indicates the number of holes per

A. Square inch
B. Linear inch
C. Square foot
D. Linear foot

Question 433

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

A. Piping
B. Cake
C. Filter medium
D. None of these

Question 434

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

A. metalliferrous ores
B. non-metallic ores
C. basic slags
D. asbestos & mica

Question 435

The grinding in a hammer crusher takes place due to the

A. Attrition
B. Impact
C. Both A & B
D. Neither A nor B

Question 436

Jigging is a technique by which different particles can be

A. separated by particle size.
B. separated by particle density.
C. separated by particle shape.
D. mixed.

Question 437

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

Question 438

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).

A. Weber
B. Peclet
C. Brinkman
D. Schmidt

Question 439

There is practically no alternative/competitor to __________ in the beneficiation treatment of sulphide ores.

A. Classification
B. Tabling
C. Jigging
D. Froth floatation

Question 440

Horsepower required for a roll crusher is directly proportional to its

A. Reduction ratio
B. Capacity
C. Both A & B
D. Neither A nor B

Question 441

Pine oil used in froth floatation technique acts as a/an

A. Collector
B. Modifier
C. Frother
D. Activator

Question 442

Crushing efficiency of a machine ranges between __________ percent.

A. 0.1 to 2
B. 5 to 10
C. 20 to 25
D. 50 to 70

Question 443

Jigging is a technique by which different particles can be

A. Separated by particle size
B. Separated by particle density
C. Separated by particle shape
D. Mixed

Question 444

Which of the following oxides is not present in hematite iron ore?

A. Titanium oxide
B. Calcium oxide
C. Cobalt oxide
D. Manganese oxide

Question 445

Pick out the correct statement.

A. The capacity and the effectiveness of a screen are the same
B. The capacity and the effectiveness of screen are opposing factors
C. The screening surface of a
D. Both B and C

Question 446

Tank filter (e.g., Nutsch filter) is

A. A high pressure filter
B. A continuous filter
C. Used for small scale filtration work
D. A leaf filter

Question 447

Pick out the correct statement:

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

Question 448

A 30% (by volume) suspension of spherical sand particles in a viscous oil has a hindered settling velocity of 4.44 μm/s. If the Richardson Zaki hindered settling index is 4.5, then the terminal velocity of a sand grain is

A. 0.90 μm/s
B. 1 μm/s
C. 22.1 μm/s
D. 0.02 μm/s

Question 449

In case of a revolving mill, wet grinding compared to dry grinding

A. Requires more energy
B. Has less capacity
C. Complicates handling & classification of the product
D. None of these

Question 450

__________ is the most commonly used 'filter aid'.

A. Diatomaceous earth
B. Fuller's earth
C. Vermiculite
D. Semi-plastic clay

Question 451

Which of the following is a vacuum filter?

A. Filter press
B. Rotary disc filter
C. Batch basket centrifuge
D. Tank filter (Nutsch filter)

Question 452

Mixing of plastic solids is generally facilitated by

A. Dispersion
B. Mastication
C. Kneading
D. None of these

Question 453

Mixing mechanism employed in a pan mixer is by

A. Mulling
B. Kneading
C. Dispersion
D. None of these

View Answer