me op1 Flashcards
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
D
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.
A
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
A
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
C
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.
A
For sizing of fine materials, the most suitable equipment is a
A. trommel
B. grizzly
C. shaking screen
D. vibrating screen
D
Which of the following is not categorised as a “mechanical
operation”?
A. Agitation
B. Filtration
C. Size enlargement
D. Humidification
D
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.
B
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.
A
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
C
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’.
D
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.
C
Which of the following relationships between co-efficient 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
B
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.
C
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
C
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.
C
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
B
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.
C
__________ centrifuge is normally used in sugar mills.
A. Tubular bowl
B. Disc-bowl
C. Suspended batch basket
D. Perforated horizontal basket continuous
C
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
B
Diatomaceous earth is a/an
A. Explosive
B. filter aid
C. filter medium
D. catalyst
B
The distribution given by microscopic analysis of powder is
A. number
B. length
C. area
D. volume
A
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
A
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.
A
In washing type plate and frame filter press, the ratio of washing
rate to the final filtrate rate is
A. 4
B. ¼
C. 1
D. ½
B
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
C
Size reduction of __________ is accomplished in steam heated
rollers and roll crushers.
A. Resins
B. Gums
C. hard rubber
D. waxes
C
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
A
Which of the following is not a part of the Blake jaw crusher?
A. Hanger
B. Check plates
C. Toggles
D. Pitman
A
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
D
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.
C
Which of the following mineral dressing operations is termed as
‘comminution’?
A. Panning
B. Spiralling
C. Tabling
D. None of these
D
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).
D
Gravity settling process is not involved in the working of a
A. Hydrocyclone
B. Classifier
C. dorr-thickener
D. sedimentation tank
A
Froth floatation is the most suitable for treating
A. iron ores
B. sulphide ores
C. quartzite
D. none of these
B
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
C
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
D
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.
A
Range of compressibility co-efficient of the commercial
compressible cake obtained in filtration operation is
A. to 0.1
B. 0.1 to 0.3
C. 0.2 to 0.8
D. 0.2 to 0.4
C
Highly viscous liquids & pastes are agitated by
A. Propellers
B. turbine agitators
C. multiple blade paddles
D. none of these
C
The value of ‘angle of nip’ is generally about
A. 16°
B. 32°
C. 52°
D. 64°
B
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
A
Sulphuric acid mist is arrested by using a __________ scrubber.
A. packed wet
B. hollow wet
C. venturi
D. co-current
C
the main size reduction operation in ultrafine grinders is
A. cutting
B. attrition
C. compression
D. impact
B
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).
D
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.
A
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
A
Balls for ball mills are never made of
A. forged/cast steel
B. lead
C. cast iron
D. alloy steel
B
200 mesh screen means 200 openings per
A. cm2
B. cm
C. inch
D. inch2
C
________ is the most commonly used ‘filter aid’.
A. Diatomaceous earth
B. Fuller’s earth
C. Vermiculite
D. Semi-plastic clay
A
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
B
For transporting pasty material, one will use a/an
A. apron conveyor
B. belt conveyor
C. screw conveyor
D. bucket elevator
C
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
A
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
A
Trommels separate a mixture of particles depending on their
A. size
B. density
C. wettability
D. electrical and magnetic properties
A
Basic slag is not ground in
A. jaw crushers
B. ball mills
C. compartment mills
D. tube mills
A
Grindability of a material does not depend upon its
A. elasticity
B. hardness
C. toughness
D. size
D
Shape factor for a cylinder whose length equals its diameter is
A. 1.5
B. 0.5
C. 1.0
D. 2.0
A
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
D
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
A
Dust laden air can be purified using a
A. cyclone separator
B. bag filter
C. gravity settler
D. tubular centrifuge
A
Vacuum is applied in _____ zone, in case of a general type
continuous rotary drum vacuum filter.
A. filtering
B. washing
C. drying
D. all
D
Filtration of water in paper mill is done by a/an _______ filter.
A. open sand
B. plate and frame
C. vacuum leaf
D. sparkler
A
General crushing equation is given by d
Bond’s crushing law is obtained by solving this equation for n = _______
and feed of infinite size.
A. 1
B. 1.5
C. 2
D. 2.5
B
Which of the following mechanical conveyors does not come
under the division ‘scrapers’?
A. Ribbon conveyor
B. Flight conveyor
C. Bucket elevators
D. Drag conveyor
C
_______ mixer is used for devulcanizing of rubber scrap &
making water dispersion & rubber solution.
A. Tumbler
B. Banbury
C. Muller
D. Ribbon blender
B
Screen capacity is not a function of
A. its opening size
B. screening mechanism
C. screening surface
D. atmospheric humidity
D
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.
A
Which of the following is a vacuum filter?
A. Filter press
B. Rotary disc filter
C. Batch basket centrifuge
D. Tank filter (Nutsch filter)
B
Pine oil used in froth floatation technique acts as a/an
A. collector
B. modifier
C. frother
D. activator
C
Length/diameter ratio of ball mill is
A. 1.5
B. 1
C. < 1
D. >1
C
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
B
Feed size of ≥ 25 cms can be accepted by
A. ball mill
B. rod mill
C. fluid energy mill
D. jaw crusher
D
Which is the most suitable conveyor for transportation of sticky
material?
A. Apron conveyor
B. Belt conveyor
C. Screw conveyor
D. Pneumatic conveyor
C
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
C
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
B
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
B
Moore filter is a _______ filter.
A. leaf
B. press
C. rotary
D. sand
A
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
B
Crushing efficiency is the ratio of the
A. Surface energy created by using 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 the crushing.
D. Energy absorbed by the solid to the surface energy
created by the crushing.v
A
The power number of a stirred tank becomes constant at high
Reynolds number. In this limit, the variation of power in put with
impeller rotational speed (N) is proportional to
A. N0
B. N1
C. N2
D. N3
C
Ball miss is used for
A. crushing
B. coarse grinding
C. fine grinding
D. attrition
C
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
A
Maximum size reduction in a ball mill is done by the, ______
action.
A. attrition
B. compression
C. impact
D. cutting
C
Increasing the capacity of a screen _______ the screen
effectiveness.
A. decreases
B. increases
C. does not effect
D. none of these
A
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
A
The controlling resistance in a rotary drum vacuum filter is the
________ resistance.
A. piping
B. cake
C. filter medium
D. none of these
B
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
B
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
B
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
A
Cement clinker is reduced to fine size by a
A. roll crusher
B. ball mill
C. tube mill
D. hammer mill
C
The crushed material received for separation is called feed or
______
A. tailing
B. heading
C. concentrate
D. middling
B
For spheres, volume shape factor is given by
A. 𝜋(=𝐴/𝐷)
B. 2𝜋(=2𝐴/𝐷)
C. 𝜋/6(=𝑉/𝐷)
D. 𝐴𝐷/𝑉
C
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
B
_________ 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
B
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
A
Use of baffles in agitators in minimising the ______ tendency.
A. swirling
B. vortexing
C. both a & b
D. neither a nor b
C
_________ are used for the separation of coarse particles from
a slurry of fine particles.
A. Thickeners
B. Classifiers
C. Hydrocyclones
D. Decanters
B
According Bond crushing law, the work required to form particle
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)
B. Sqrt (𝑆/𝑉)
C. (𝑆/𝑉)
D. (𝑆/𝑉)
B
_________ is the most suitable for compounding rubber and
plastic solids.
A. Banbury mixer
B. Pan mixer
C. Pug mill
D. Charge can mixer
A
Fibrous material is broken by a
A. roll crusher
B. squirrel-cage disintegrator
C. ball mill
D. tube mill
B
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
B
The most common filter aid is
A. diatomaceous earth
B. calcium silicate
C. sodium carbonate
D. silica gel
A
For separation of sugar solution from settled out mud, we use a
___ filter.
A. sparkler
B. plate and frame
C. centrifugal
D. rotary vacuum drum
C
the sphericity of a cylinder of 1mm diameter and length 3 mm is
A. 0.9
B. 0.78
C. 0.6
D. 0.5
A
What is the selectivity index, if the grade of tailings & concentrate
is the same?
A. 0
B. ∞
C. 1
D. 0.5
C
Traces of solids are removed from, liquid in a
A. classifier
B. clarifier
C. sparkler filter
D. rotary vacuum filter
D
____ 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
D
The speed of a rotary drum vacuum filter may be about _______
rpm.
A. 1
B. 50
C. 100
D. 500
A
Colloid mills achieve size reduction mainly by
A. impact
B. attrition
C. cutting
D. compression
B
Mesh indicates the number of holes per
A. square inch
B. linear inch
C. square foot
D. linear foot
B
Out of the following size reduction equipment, the maximum
feed size can be accepted by the
A. tube mill
B. ball mill
C. jaw crusher
D. jet pulveriser
C
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 diameter of ______ mm.
A. 0.007
B. 0.30
C. 50
D. 0.014
B
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
C
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
A
