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