me op 4 Flashcards
_____ mills fall in the category of tumbling mills,
A. Ball and pebble
B. Rod and tube
C. Compartment
D. All
D
Which of the following is not a cutting machine?
A. Dicers
B. Knife cutters
C. Slitters
D. Tube mills
D
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
C
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
D
Screen efficiency is
A. recovery/rejection
B. recovery
C. rejection
D. none of these
D
Handling of ashes and similar materials can be done best by a
______ conveyor.
A. flight
B. drag or slat
C. belt
D. ribbon
B
200 mesh sieve size corresponds to ____ microns.
A. 24
B. 74
C. 154
D. 200
B
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
B
Apron conveyors are used for
A. heavy loads & short runs
B. small loads & long runs
C. heavy loads & long runs
D. none of these
A
Sedimentation on commercial scale occurs in
A. classifiers
B. thickeners
C. rotary drum filters
D. cyclones
C
With increase in drum speed, in a rotary drum filter, the filtration
rate
A. increases
B. increases linearly
C. decreases
D. is not affected
A
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
A
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, meter/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
A
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°
B
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
A
For a turbine agitated and baffled tank, operating at low
Reynold’s number (based on impeller diameter), the power
number (𝑁) varies with 𝑁 as
A. 𝑁p ∝𝑁re
B. 𝑁p ∝ sqrt(𝑁re)
C. 𝑁p→𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
D. Np ∝1/Nre
D
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 liquids in form of emulsion.
D. Suspending solid particles.
B
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
B
A 30% (by volume) suspension of spherical sand particles in a
viscous oil has a hindered settling velocity of 4.44 um/s. if the
Richardson Zaki hindered settling index is 4.5, then the terminal
velocity of a sand grain is
A. 0.90 um/s
B. 1 um/s
C. 22.1 um/s
D. 0.02 um/s
B
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
A
Velocity of a small particle of diameter ‘DP’ at a distance ‘r’ from
the rotational axis of a cyclone rotating at an angular speed ‘𝜔’
is given by (the other symbols are as per standard notation)
A. (Dp/18 - ps-p/u) 𝜔^2𝑟
B. (Dp^2/18 - ps-p/u)𝜔𝑟^2
C. (Dp/18 - ps-p/u) 𝜔^2𝑟^2
D. (Dp^2/18 - ps-p/u)𝜔^2𝑟
D
In froth flotation, chemical agent added to cause air adherence
is called
A. collector
B. frother
C. modifier
D. activator
A
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
B
Vertical transportation of materials can be done by a/an
A. apron conveyor
B. pneumatic conveyor
C. bucket elevator
D. both b & c
D
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 and b
D. neither a nor b
C
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
C
A Cottrell precipitator makes use of the __ for dusty air cleaning.
A. electric spark
B. corona discharge
C. alternating current
D. none of these
B
Pick out the correct statement.
A. Plastic chips are called non-cohesive solids.
B. Kick’s crushing law is, 𝑃/𝑚=𝐾∙ln(Dsa/Dsb)
C. Comminution 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’.
B
If radius of a batch basket centrifuge is halved & the rpm 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.
C
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
D
Compressibility coeff. for an absolutely compressible cake is
A. 0
B. 1
C. 0 to 1
D. ∞
B
Mixing of plastic solids is generally facilitated by
A. dispersion
B. mastication
C. kneading
D. none of these
C
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 and b
D. neither a nor b
C
Which of the following is not an industrial screening equipment?
A. Sharpies centrifuge
B. Vibrating screen
C. Grizzly
D. Trommel
A
Which of the following is not a wet classifier?
A. Sharpies supercentrifuge
B. Hydrocyclones
C. Dorr Oliver rake classifier
D. None of these
D
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
A
For Raschig rings, the sphericity is
A. 0.5
B. 1
C. <1
D. √3
C
_______ mills are termed as disintegrators.
A. Cage
B. Compartment
C. Pebble
D. All tumbling
A
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
B
The cumulative mass fraction of particles smaller than size dj for
a collection of Ni particles of diameter di and mass mi (i = 1, 2, 3,
….. ∞) is given by
A. ∑ 𝑁𝑑^3 /∑ 𝑁𝑑^3
B. ∑ 𝑁𝑚𝑑^3 /∑ 𝑁𝑚𝑑^3
C. ∑ 𝑁𝑚𝑑^2 /∑ 𝑁𝑚𝑑^2
D. ∑ 𝑁𝑚𝑑/∑ 𝑁𝑚𝑑
B
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
C
The grinding in a hammer crusher takes place due to the
A. attrition
B. impact
C. both a & b
D. neither a nor b
C
A compressible cake has the
A. maximum porosity at the upstream side.
B. maximum porosity at the filter medium.
C. same porosity through the cake thickness.
D. none of these
A
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
D
In ball mill operation, the feed size (Df in meters) and the ball
diameter (Db in meters) are related as (where, K = grindability
constant (varying from 0.9 to 1.4 in increasing order of
hardness)).
A. 𝐷^2 =𝐾.𝐷
B. 𝐷=𝐾.𝐷
C. 𝐷^3 =𝐾.𝐷
D. 𝐷^2=𝐾.𝐷^2
A
Pine oil cresylic acid are used as ______ in the froth floatation
process.
A. frother
B. collector
C. depressor
D. conditioner
A
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. unbalanced fly wheels
D. either a, b or c
D
Grinding characteristic of a material is given by its
A. HGI
B. angle of repose
C. shatter index
D. abrasion
A
Which of the following is not a non-metalliferous mineral?
A. Calcite
B. Fluorspar
C. Quartz
D. Cassiterite
D
Filter medium resistance is important during the _______ of
filtration.
A. early stages
B. final stages
C. entire process
D. none of these
A
Float and sink test determine the possibility of cleaning of coal
by a process based on the
A. gravity separation
B. wettability
C. particle shape
D. none of these
A
______ baffles are provided in ball mills.
A. Horizontal
B. No
C. Only two
D. None of these
A
Mixer used for rubber compounding is
A. mixer-extruder
B. banbury internal mixer
C. muller mixer
D. pug mill
B
For spheres, the specific surface shape factor is given by
A. AD/V
B. D/V
C. A/V
D. SQRT(𝐴𝐷/𝑉)
A
______ 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
D
In case of hammer crusher, the final product size depends on
the
A. feed rate
B. rotor speed
C. clearance between hammer & grinding plates
D. all
D
Sphericity of Raschig ring (whose length and diameter are
equal) is
A. >1
B. <1
C. 1
D. 2
C
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
C
Mixing mechanism employed in a pan mixer is by
A. mulling
B. kneading
C. dispersion
D. none of these
A
Chance process is used for the
A. cleaning of coal
B. concentration of iron ore
C. concentration of pyrites
D. water treatment
A
Which of the following screens has the maximum capacity?
A. Grizzlies
B. Trommels
C. Shaking screen
D. Vibrating screen
D
Stamp mills are generally used for crushing
A. iron ores
B. gold ores
C. talc
D. diamond
B
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
C
Which of the following is a batch sedimentation equipment?
A. Dust catcher
B. Filter thickener
C. Dry cyclone separator
D. Rotary sprayer scrubber
B
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
B
Which of the following is not used as filter aid?
A. Asbestos
B. Diatomaceous earth
C. Purified wood cellulose
D. Rice husk
D
Raw materials are charged in the iron blast furnace using
A. bucket elevator
B. skip hoist
C. screw conveyor
D. none of these
B
Carbon black is pulverised in a
A. hammer crusher
B. ball mill
C. roll crusher
D. gyratory crusher
B
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
C
The most efficient equipment for the removal of sub-micronic
dust particles from blast furnace gas is the
A. venturi atomiser
B. gravity fettling chamber
C. electro-static precipitator
D. cyclone separator
C
The filtrate flow rate in constant pressure filtration
A. continuously increases.
B. continuously decreases.
C. remains constant throughout.
D. may increase or decrease; depends on the pressure.
B
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
A
The inlet pressure in a constant rate filtration
A. increases continuously
B. decreases gradually
C. remains constant
D. none of these
A
Size reduction of moulding powders, waxes, resins & gums are
done in a ______ mill.
A. cage
B. hammer
C. both a and b
D. neither a nor b
C
________ 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
C
For beneficiation of iron ore, most commonly used method is
A. flocculation
B. froth flotation
C. jigging & tabbing
D. none of these
C
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
A
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
D
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 6V/DS
B. V/6DS
C. DS/V
D. V/DS
A
Screen capacity is proportional to (where, S = screen aperture)
A. S
B. 1/S
C. S^2
D. √S
A
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 (up to 1.25 cm).
D. Dry grinding of large particles in un-baffled mills.
D
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
C
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
B
Reciprocal of sphericity is termed as the
A. specific surface ratio
B. shape factor
C. Sauter diameter
D. surface are per unit mas
B
With increases 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
A
Pick out the wrong statement.
A. Hammer crushers operate by impact action.
B. Standard screens have circular opening.
C. With increases in mesh number of screens, their
diameter in microns decreases.
D. 200 mesh screen has 200 openings per linear cm.
D
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
B
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.
A
The capacity of a gyratory crusher is ______ that of a jaw
crusher with the same page, handling the same feed & for the
same product size range.
A. Same as
B. 2.5 times
C. 5 times
D. 10 times
B
Xanthates are used in the froth floatation process as a/an
A. conditioner
B. frother
C. collector
D. activator
C
The ratio of the actual mesh dimension of Taylor series to that
next smaller screen is
A. 2
B. √2
C. 1.5
D. √3
B
Limestone is normally crushed in a
A. roll crusher
B. hammer crusher
C. ball mill
D. tube mill
B
Filtrate flow rate in case of a rotary drum vacuum filter (in which
Rm «_space;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
D
Pick out the correct statement.
A. The capacity and the effectiveness of a screen are the
same.
B. The capacity and the effectiveness pf screen are
opposing factors.
C. The screening surface of a ‘reel’ (a revolving screen
used in flour mills) is made of silk bolting cloth
supported by wire mesh.
D. Both b and c
D
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
A
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
C
Use of grinding aids results in the
A. enhanced production rate
B. finer products
C. both a & b
D. neither a nor b
D
A belt conveyor used for the transportation of materials can
A. run up to 1 km.
B. travel at a speed up to 300 metres/minute.
C. handle materials up to 5000 tons/hr.
D. all
D
_____ mill is not a revolving mill.
A. Pebble
B. Compartment
C. Cage
D. Tube
C
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
B
For the transportation of ultrafine particles, the equipment used
is a _______ conveyor.
A. Belt
B. Pneumatic
C. Screw
D. None of these
B
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
D
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
D
Which of the following is a fine crusher?
A. Blake jaw crusher
B. Gyratory crusher
C. Toothed roll crusher
D. Dodge jaw crusher
C
_______ is a cohesive solid.
A. Wheat
B. Sand
C. Wet clay
D. None of these
C
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
A
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
D
Dispersion of a gas through liquid is done by using
A. sparger
B. kneader
C. masticator
D. none of these
A
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
A
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
A
What is the reduction ratio in a fine crushing operation having
following feed and product sizes? (mm)
Parameters , Maximum, Minimum
Feed size 20 10
Product size 10 05
A. 0.5
B. 2
C. 5
D. 10
B
