me op 3 Flashcards
Maximum size reduction in a fluid energy mill is achieved by
A. compression
B. interparticle attrition
C. cutting
D. impact
B
Filtration rate through a filter cake is proportional to (where, S =
filtering surface R = specific cake resistance Β΅ = viscosity of the
filtrate)
A. S
B. 1/R
C. 1/ Β΅
D. All
D
A centrifugal filtration unit operating at aa rotational speed of w
has inner surface of the liquid (density πL) located at a radial
distance R from the axis of rotation. The thickness of the liquid
film is πΏ and no cake is formed. The initial pressure drop during
filtration is
A. 1/2π€^2 βπ
^2 βππΏ
B. 1/2π€^2 βπΏ^2 βππΏ
C. 1/2π€^2 βπΏππΏβ(2π
+πΏ)
D. 1/2π€^2 βπ
βππΏ(π
+2πΏ)
D
Which one is a filter aid?
A. Canvas fabric
B. Diatomaceous earth
C. Calcined lime
D. None of these
B
To remove dirt from the flowing fluid, we use a
A. coagulant
B. gravity settler
C. strains
D. clarifier
C
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
C
Separation of solid suspended in liquid into a supernatant clear
liquid and a denser slurry employs a process termed
A. coagulation
B. flocculation
C. sedimentation
D. clarification
C
Ultrafine grinders operate principally by
A. slow compression
B. impact
C. attrition
D. cutting action
C
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
A
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
A
Screen capacity is expressed in terms of
A. tons/hr
B. tons/ft2
C. both a & b
D. tons/hr- ft2
D
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.
C
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 ?
0.5
1.0
2.76
0.66
D
Percentage of drum submerged in the slurry in case of rotary
drum filter is
A. 3
B. 30
C. 85
D. 25
B
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
C
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
C
Critical speed rotation, N (in rps β rotation per second) of a
trammel is equal to (where, g = acceleration due to gravity = 9.81
m/sec2 and, r = radius of trammel, metre).
A. 1/2n sqrt(g/r)
B. 1/n sqrt(g/r)
C.1/2 sqrt(g/r)
D. 2πβ sqrt(g/r)
A
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
B
For the preliminary breaking of hard rock, we use
A. gyratory crusher
B. ball mill
C. tube mill
D. squirrel-cage disintegrator
A
Filtration operation carried out by continuous increase of the
inlet pressure of slurry, is called ________ filtration.
A. constant rate
B. varying pressure
C. varying rate
D. constant pressure
A
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 do
B
Which of the following oxides is not present in hematite iron ore?
A. Titanium oxide
B. Calcium oxide
C. Cobalt oxide
D. Manganese oxide
C
Ribbon blenders are exclusively meant for
A. blending miscible liquids.
B. non-flowing powder and thin pastes.
C. bath mixing.
D. continuous mixing.
B
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.
D
Tube mill compared to ball mill
A. produces finer products.
B. is long in comparison with its diameter.
C. uses smaller balls.
D. all
D
Gelatinous solid (which plug the septum) can be filtered by a
______ filter.
A. Sparkler
B. plat and frame
C. vacuum leaf
D. precoat
D
During the washing of cake
A. all the resistance are constant.
B. filter medium resistance increases.
C. filter medium resistance decreases.
D. cake resistance decreases.
D
The opening of a 200 mesh screen (Taylor series) is
A. 0.0074 cm
B. 0.0074 mm
C. 0.0047 cm
D. 74 milli-microns
A
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
A
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
B
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 βmodifying agentβ (for activating or
depressing the adsorption of filming agents? In froth
floatation process.
B
Separation of solid particles based on their densities is called
A. sizing
B. sorting
C. clarification
D. dispersion
B
______ are mixed using ribbon blenders.
A. Lumpy solids and low viscosity liquids
B. Dry powders
C. High viscosity liquids
D. Thick pastes
B
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 surface
(e.g., the centre vortex) on the power number.
D. All
D
For crushing of solids, the Rittingerβs 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
A
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
C
Pick out the wrong statement.
A. More commonly used jaw crusher between Dodge jaw
crusher and Blake jaw crusher is the latter one.
B. There are only four methods namely compression,
impact, attrition and cutting, which the size reduction
equipment employ.
C. Cutting machines mainly employ βattritionβ for size
reduction of solids.
D. Operating principles of Dodge and Blake jaw crushers
are combined in the working of universal jaw crushers.
C
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
B
As per Taggartβs formula, the capacity (kg/hr) of Jaw & Gyratory
crushers (for gapes of 10 to 60 cm) is equal to (where, L = length
of feed opening, cm S = Max width of discharge opening, cm).
A. LS
B. 93 LS
C. 250 LS
D. βπΏS
B
The process by which fine solids is removed from liquids is
termed as
A. decantation
B. flocculation
C. sedimentation
D. classification
C
Which of the following crushing laws is most accurately
applicable to the fine grinding of materials?
A. Bondβs crushing law
B. Kickβs law
C. Rittingerβs law
D. None of these
C
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
D
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
A
Which of the following is a course crusher?
A. Smooth roll crusher
B. Toothed roll crusher
C. Gyratory crusher
D. Tube mill
C
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
C
Separation of particles of various sizes, shapes, and densities
by allowing them to settle in a fluid is called
A. classification
B. froth flotation
C. thickening
D. clarification
A
The specific cake resistance for incompressible sludges is
(where βπ = pressure drop over cake)
A. ββπ
B. β1/βπ
C. βββπ
D. Independent of
βπ
D
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. 1.0
B. 0.5
C. 1.34
D. 4.34
C
To produce talcum powder, use
A. ball mill
B. hammer mill
C. jet mill
D. pin mill
A
Angle 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
B
Paddle agitator
A. is suitable for mixing low viscosity liquids.
B. produces axial flow.
C. moves at very high speed.
D. none of these
A
Gummy & sticky materials like molasses, sugar etc. are best
transported/handled by using a ______ conveyor.
A. Drag
B. Ribbon
C. Screw
D. Slat
B
Soft & non-abrasive materials can be made into fines by
A. attrition
B. compression
C. cutting
D. none of these
A
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
D
The critical speed of a trommel (N) is related to its diameter (D)
as
A. πβ 1/βD
B. πββπ·
C. πβπ·
D. πβ 1/D
A
Which of the following minerals is not subjected to magnetic
separation method?
A. Rutile
B. Galena
C. Chromite
D. Siderite
B
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
C
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
B
A fluid energy mill is used for
A. cutting
B. grinding
C. ultragrinding
D. crushing
C
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 b & c
D
For coarse reduction of hard solids, use
A. impact
B. attrition
C. compression
D. cutting
C
Traces of liquid tar fog present in coke oven gas is separated is
separated using
A. electrostatic precipitator
B. cyclone separator
C. strainer
D. none of these
A
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
C
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
C
The specific surface of spherical particles is proportional to
(where, Dp = diameter of particle).
A. π·^2 p
B. π·p
C. 1/π·p
D. 1/π·^2 p
C
Wheat is ground into flour in a
A. hammer crusher
B. roller crusher
C. impact mill
D. fluid energy mill
B
Gravity stamp mill is meant for the _____ crushing.
A. primary
B. intermediate
C. fine
D. ultrafinE
C
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
A
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
C
To get ultrafine particles, the equipment used is a
A. ball mill
B. rod mill
C. hammer crusher
D. fluid energy mill
D
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.
B
Vacuum filter is most suitable for the
A. removal of fines from liquid.
B. liquids having high vapor pressure.
C. liquids of very high viscosity.
D. none of these
D
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.
A
Which of the following conveyors cannot be recommended for
transport of abrasive materials?
A. Belt conveyor
B. Apron conveyor
C. Flight conveyor
D. Chain conveyor
C
Separation of materials into products based on the difference of
their sizes is called
A. sizing
B. sorting
C. classification
D. flocculation
A
for classification of potable (drinking) water, we use a ______
filter.
A. gravity sand
B. plate and frame
C. vacuum leaf
D. rotary vacuum
A
Hot, lumpy & abrasive materials are best transported by using
a/an _______ conveyor.
A. apron
B. blet
C. screw
D. flight
A
Additives used for promoting the flocculation of particles is a/an
A. electrolyte
B. surface active agent
C. both a & b
D. neither a nor b
C
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 product.
D. all
D
The capacity of a classifier in βtons of solid/hrβ 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, Ο = density
of solids, kg/m3)
A. 3.6 AVS. Ο
B. 3.6 A.V. Ο
C. 3.6 A.S. Ο
D. 3.6 AVS/ Ο
A
Kickβs law relates to
A. energy consumption
B. final particle size
C. feed size
D. none of these
A
________ mill is normally used for grinding of talc.
A. tube
B. compartment
C. ring-roll
D. pebble
C
Colloidal mills are used for _______ grinding.
A. coarse
B. intermediate
C. fine
D. ultrafine
D
Fluid medium used in the classification technique of mineral
beneficiation is
A. air
B. water
C. both a & b
D. neither a nor b
C
The maximum slope pf a belt conveyor can be
A. 15Β°
B. 30Β°
C. 45Β°
D. 60Β°
B
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
C
The unit of filter medium resistance is
A. cm-1
B. gm/ cm-1
C. cm/ gm-1
D. gm-1
A
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
C
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
D
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.
A
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
D
In the cyclone separator used for separation of dust from 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 & c
D
The basic filtration equation is given as__ where, V is volume of the filtrate; A is the filtration area, a is
specific cake resistance, u is viscosity of the filtrate, and C is the
concentration of the solids in the feed slurry.
In a 20 minutes constant rate filtration, 5 m3 of the filtrate was
obtained. If this is followed by a constant pressure filtration, how
much more time in minutes, it will take for another 5 m3 of filtrate
to be produced? Neglect filter medium resistance, RM; assume
incompressible cake.
A. 10
B. 20
C. 25
D. 30
B
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. Bradfordβs breaker
B
The material is crushed in a gyratory crusher by the action of
A. impact
B. compression
C. attrition
D. cutting
B
The equivalent diameter of channel of a constant non-circular
cross section of 3 cm by 6 cm will be ________ cm.
A. 20
B. 12
C. 8
D. 2
D
Which of the following may prove unsuitable for filtering volatile
liquids?
A. Pressure filter
B. Gravity filter
C. Centrifugal filter
D. Vacuum filter
D
_______ mean diameter of particles is given by βπ₯/π·β
A. Mass
B. Volume
C. Arithmetic
D. Volume surface
B
Sauter mean diameter is the same as the _____ mean diameter
A. mass
B. arithmetic
C. volume surface
D. geometric
C
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
D
In paint industries, blending of light paste is done by using a
A. masticator
B. charge can mixer
C. kneader
D. none of these
B
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. 0.50
B. 0.58
C. 0.68
D. 0.62
A
_______ 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
C
Wet sieving is employed, when the product contains ________
materials.
A. abrasive
B. large quantity of very fine
C. coarse
D. non-sticky
B
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
D
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
D
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
D
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
B
Mass flow of granular solid (M) through a circular opening of dia,
D follows
A. πββπ·
B. πβπ·^2
C. πβπ·^3
D. πβπ·
C
The term βangle of nipβ is concerned with the operation of the
_______ crushers.
A. jaw
B. roll
C. gyratory
D. none of these
B
Cartridge filters are termed as βedgeβ 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
C
Vibrating screens have capacity in 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
A
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
C
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
D
Screw conveyors are
A. run at very high rpm
B. suitable for sticky materials
C. suitable for high abrasive materials
D. all
B
