1
Q
A unit operation where a mixture of various sizes of particles is separated into two or more portions, each of which is more uniform in particle size than the original mixture by allowing the material to pass over a surface provided with the openings of the desired size.
A
Screening
2
Q
In screen analysis, notation 10mm/5mm means passing through
a. 10 mm screen and retained on 5 mm screen
b. 5mm screen and retained on 10mm screen
c. both 5 mm and 13 mm screens
d. neither 5 mm nor 10 mm screens
A
10 mm screen and retained on 5 mm screen
3
Q
For sizing of fine materials, the most suitable equipment is a
a. trommel
b. shaking screen
c. grizzly
d. vibrating screen
A
vibrating screen
4
Q
200 mesh screen means 200 openings per
a. cm^2
b. inch
c. cm
d. inch^2
A
inch
5
Q
The opening of a 200-mesh screen (Tyler series) is
a. 0.0074 cm
b. 0.0047 cm
c. 0.0074 mm
d. 74 millimicrons
A
0.0074 cm
6
Q
A series of testing sieves having openings in a fixed succession. The ratio of aperture of a given sieve to the aperture of the next one in a sieve series is constant.
A
Sieve Scales
7
Q
Clear space between the individual wirres of the screen.
A
Screen Aperture
8
Q
Number of apertures per linear inch
A
Mesh Number
9
Q
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.
A
200 mesh screen has 200 openings per linear cm.
10
Q
Screen efficiency is
a. recovery/rejection
b. rejection
c. recovery
d. none of these
A
none of these (recovery*rejection)
11
Q
Increasing the capacity of screen
a. decreases the screen effectiveness
b. does not affect the screen effectiveness
c. increases the screen effectiveness
d. none of these
A
decreases the screen effectiveness
12
Q
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
A
screening becomes progressively more difficult
13
Q
Screen capacity is not a function of
a. its openings size
b. screening surface
c. screening mechanism
d. atmospheric humidity
A
atmospheric humidity
14
Q
Is a measure of how closely the shape of an object resembles that of a perfect sphere.
A
Sphericity
15
Q
Size measurement of ultrafine particles can be best expressed in terms of
a. centimeters
b. micron
c. screen size
d. surface area/unit mass
A
surface area/unit mass
16
Q
Sphericity of Raschig ring (whose length and diameter are equal) is
A
1
17
Q
The hardness of a mineral is a criterion of its resistance to crushing. Which of the following is an example of a hard material?
a. talc
b. calcite
c. sapphire
d. feldspar
A
sapphire/corrundum
18
Q
Which of the following is the softest material?
a. talc
b. corundum
c. feldspar
d. calcite
A
talc
19
Q
involves the production of smaller mass units from larger mass units of the same material.
A
Size Reduction
20
Q
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. primary
b. fine
c. secondary
d. ultrafine
A
Primary
21
Q
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. fine
c. secondary
d. ultrafine
A
secondary
22
Q
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. fine
c. secondary
d. ultrafine
A
fine
23
Q
Feed size of ≥ 25 cms can be accepted by
a. ball mill
b. fluid energy mill
c. rod mill
d. jaw crusher
A
jaw crusher
24
Q
For the preliminary breaking of hard rock, we use
a. gyratory crusher
b. ball mill
c. tube mill
d. quirrel-cage disintegrator
A
gyrator crusher
25
The material is crushed in a gyratory crusher by the action of
a. impact
b. attrition
c. compression
d. cutting
compression
26
Size reduction does not occur due to compression in case of
a. rod mills
b. jaw crushers
c. gyratory crushers
d. smooth roll crushers
rod mills
27
Gyratory crushers compared to the reciprocating jaw crushers
a. have greater capacity per unit of discharge area.
b. crush intermittently.
c. are less suitable for coarse materials.
d. have less steady power consumption.
have greater capacity per unit of dischare area
28
Size reduction of asbestos and mica is done by
a. hammer mills
b. gyratory crushers
c. rod mills
d. crushing rolls
hammer mills
29
To get ultrafine particles, the equipment used is
a. ball mill
b. rod mill
c. hammer crusher
d. fluid energy mill
fluid energy mill
30
Energy requirement (per unit mass of material crushed/ground) is highest for
a. jaw crusher
b. ball mill
c. rod mill
d. fluid energy mill
fluid energy mill
31
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
Jaw crusher, Ball mill, Fluid energy mill
32
Carbon black is pulverized in a
a. hammer crusher
b. roll crusher
c. ball mill
d. gyratory crusher
ball mill
33
Maximum size reduction in a ball mill is done by
a. attrition
b. compression
c. impact
d. cutting
impact
34
The operating speed of a ball mill should be
a. less than the critical speed
b. at least equal to the critical speed
c. much more than the critical speed
d. none of these
less than the critical speed
35
Power required to drive a ball mill with a particular ball load is proportional to (where, D = diameter of ball mill )
a. D
b. D^2.5
c. 1/D
d. 1/D2.5
D^2.5
36
The optimum moisture content in solids to be crushed/ground ranges from percent.
a. 3 to 4
b. 10 to 15
c. 8 to 10
d. 15 to 20
3 to 4
37
As the product becomes finer, the energy required for grinding
a. decreases
b. is same as for coarser grinding
c. increases
d. is 1.5 times than for coarser grinding
increases
38
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.
surface energy created by crushing to the energy absorbed by the solid
39
Kick's law relates to
a. energy consumption
b. feed size
c. final particle size
d. none of these
energy consumption
40
Which of the following gives the crushing energy required to create new surface?
a. Taggarts rule
b. Rittinger's law
c. Fick's law
d. none of these
Rittinger's Law
41
The most suitable equipment for the transportation of 200 mesh size particles is a
a. bucket elevator
b. screw conveyor
c. pneumatic conveyor
d. belt conveyor
pneumatic conveyor
42
The optimum moisture content for fine solids ranges from what percent?
a. 3 to 4
b. 10 to 15
c. 8 to 10
d. >50
>50
43
What is the n value for Bond's Law? What is its energy equation?
n=1.5;
(P/T)=k [{1/sqr(x2)}-{1/sqr(x1)}]
44
What is the n value for Rittinger's Law? What is its energy equation?
n=2;
(P/T)=k [{1/x2}-{1/x1}]
45
What is the n value for Kick's? What is its energy equation?
n=1;
(P/T)=k ln (x1/x2)
46
Alternate equation used for crushing energy calculation when particle dimension is in millimeters:
(P/T)=0.316 Wi ({1/sqrt(x2)}-1/sqrt(x1)})
47
Alternate equation used for crushing energy calculation when particle dimension is in feet:
(P/T)=1.46 Wi ({1/sqrt(x2)}-1/sqrt(x1)})
48
According to Moh's Scale for hardness, these minerals are soft:
a. Talc
b. gypsum
c. calcite
d. Fluorite
e. Apatite
f. Feldspar
g. Quartz
h. Topaz
i. Corundum/sapphire
j. Diamond
a. Talc
b. gypsum
c. calcite
49
According to Moh's Scale for hardness, these minerals are intermediate:
a. Talc
b. gypsum
c. calcite
d. Fluorite
e. Apatite
f. Feldspar
g. Quartz
h. Topaz
i. Corundum/sapphire
j. Diamond
d. Fluorite
e. Apatite
f. Feldspar
50
According to Moh's Scale for hardness, these minerals are hard:
a. Talc
b. gypsum
c. calcite
d. Fluorite
e. Apatite
f. Feldspar
g. Quartz
h. Topaz
i. Corundum/sapphire
j. Diamond
g. Quartz
h. Topaz
i. Corundum/sapphire
j. Diamond
51
Size measurement of coarse particles can be expressed in?
a. mm, in, cm
b. mesh no
c. microns
d. cm^2/g
a. mm, in, cm
52
Size measurement of fine particles can be expressed in?
a. mm, in, cm
b. mesh no
c. microns
d. cm^2/g
b. mesh no.
53
Size measurement of very fine particles can be expressed in?
a. mm, in, cm
b. mesh no
c. microns
d. cm^2/g
c. microns
54
What is the equation used to calculate for sphericity?
S=(pi^1/3 * 6^2/3 * Vp ^2/3)/(Surface Area of Particle)
55
What is the estimation formula for mesh screen diameter?
D=14.9/mesh no.
56
What is the equation for screen efficiency?
E= (Pxp/Fxf) (1-{(P(1-xp))/(F(1-xf))}
57
Using Component Balance, P/F is equal to:
P/F=(xf-xr)/(xp-xr)
58
separation of dilute into a clear fluid and dense slurry by gravity settling.
Sedimentation
59
The operation by which solids are separated from liquids due to difference in the respective densities is
a. screening
b. adsorption
c. sedimentation
d. absorption
sedimentation
60
Forces acting on a particle settling in fluid are
a. gravitational and buoyant forces
b. centrifugal and drag forces
c. gravitational or centrifugal, buoyant and drag forces
d. external, drag and viscous forces
gravitational or centrifugal, buoyant and drag forces
61
Buoyant force
a. for non-symmetrical bodies is not vertical
b. depends on the depth of the submergence of the floating body
c. depends on the weight of the floating body
d. none of these
depends on the weight of the floating body
62
Drag is defined as the force exerted by the
a. fluid on the solid in a direction opposite to flow
b. the fluid on the solid in the direction of flow
c. the solid on the fluid
d. none of these
fluid on the solid in a direction opposite to flow
63
Terminal velocity is
a. constant velocity with no acceleration
b. a fluctuating velocity
c. attained after moving one-half of total distance
d. none of these
constant velocity with no acceleration
64
Stoke’s law is valid when the particle Reynolds number is
a. <1
b. <5
c. >1
d. none of these
<1
65
For stokes law, what are the values of Re, K, b, and n?
Re <2
K <3.33
b=24
n=1
66
For intermediate law, what are the values of Re, K, b, and n?
Re = 2-500
K = 3.33 - 44
b=18.5
n = 0.6
67
For newtons law, what are the values of Re, K, b, and n?
Re >500
K > 44
b= 0.44
n=0
68
The terminal velocity of a small sphere settling in a viscous fluid varies as the
a. first power of its diameter
b. inverse of the fluid viscosity
c. inverse square of the diameter
d. square of the difference in specific weights of solid and fluid
inverse of the fluid viscosity
69
Equation for calculating terminal velocity using Intermediate Law
vt= (0.153(g^0.71)(Dp^1.14)(ρp-ρ)^0.71)/(ρ^0.29)(μ^0.43)
70
For free settling, equation for Reynolds number is
Re=(Dp)(Vt)(ρ)/μ
71
Equation for drag coefficient, Cd
Cd= b/Re^n
72
A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity
a. same as that of A.
b. twice as that of A.
c. one fourth as that of A.
d. four times as that of A.
one fourth as that of A
(answer from indiabix, correct answer should be four times as that of A)
73
In hindered settling, particles are
a. placed farther from the wall
b. near each other
c. not affected by other particles and the wall
d. none of these
near each other
74
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. 0.6
c. 0.4
d. none of these
0.6
(answer from indiabix, correct answer should be 0.4)
75
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. 22.1 μm/s
c. 1 μm/s
d. 0.02 μm/s
1 μm/s
(answer from indiabix, correct answer should be 22.1 μm/s)
76
Traces of solids are removed from liquid in a
a. classifier
b. sparkler filter
c. clarifier
d. rotary vacuum filter
clarifier
77
A mechanical process of separating multi-phase mixture via the use of centrifugal force.
Centrifugation
78
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. dispersion
c. flocculation
d. centrifugation
centrifugation
79
If the radius of a basket centrifuge is halved and the rpm is doubled, then
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
centrifugal force is doubled
80
Ultra centrifuges are used for the separation of _____ solid particles.
a. coarse
b. colloidal
c. fine
d. dissolved
colloidal
81
Where the density difference of the two liquid phases to be separated is very small (as in milk cream separator), the most suitable separator is a
a. disc bowl centrifuge
b. batch basket centrifuge
c. sharpies super centrifuge
d. sparkler filter
disc bowl centrifuge
82
Ultracentrifuges running at speeds up to 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.
separation of isotopes based on their density or molecular weights difference.
83
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
immiscible liquids of different
84
The capacity of a Sharples centrifuge is estimated to be increase/decrease by _____% if its speed is doubled and the cut size of the product is reduced by 20%.
a. 20% increase
b. 80% increase
c. 156% increase
d. 120% increase
156% increase
85
Suspended solid particles in a fluid of liquid or gas is physically or mechanically removed by using a porous medium that retains the particle as separate phase or cake and passes the clear filtrate.
Filtration
86
For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid?
a. Kozeney-Karman equation
b. Leva’s equation
c. Blake-Plummer equation
d. none of these
Kozeney-Karman equation
87
In case of a plate and frame filter press, filtrate flow through the cake follows _______ flow.
a. plug
b. laminar
c. turbulent
d. none of these
laminar
88
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
rate of filtration decreases with time
89
Filtration operation carried out by continuous increase of the inlet pressure of slurry, is called the _______ filtration.
a. constant rate
b. varying rate
c. varying pressure
d. constant pressure
constant rate
90
With increase in the pressure drop across the cake, the specific cake resistance for the compressible sludge
a. increases
b. remains constant
c. decreases
d. increases linearly
increases
91
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 batch filter
92
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.
at the end of filtration.
93
Which of the following represents the plot of filtrate volume versus time for constant pressure filtration?
a. Parabola
b. Hyperbola
c. Straight line
d. Exponential curve
Parabola
94
In washing type plate and frame filter press, the ratio of washing rate to the final filtrate rate is
a. 4
b. 1
c. 1/4
d. 1/2
1/4
95
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.
square root of the velocity.
96
Filter aid is used
a. to increase the rate of filtration
b. to decrease the pressure drop
c. to increase the porosity of the cake
d. as a support base for the septum
to increase the porosity of the cake
97
Which of the following is not used as filter aid?
a. Asbestos
b. Diatomaceous earth
c. Purified wood cellulose
d. Rice husk
Rice husk
98
_______ is the most used ‘filter aid’.
a. Diatomaceous earth
b. Vermiculite
c. Fuller’s earth
d. Semi-plastic clay
Diatomaceous earth
99
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.
deplugging the filter medium.
100
For removal of very small amounts of precipitate from large volume of water, the most suitable filter is the ______ filter.
a. plate and frame
b. sand
c. shell and leaf
d. rotary vacuum
sand
101
Filtration of water in a paper mill is done by a/an ______ filter.
a. open sand
b. vacuum leaf
c. plate and frame
d. sparkler
open sand
102
For separation of sugar solution from settled out mud, we use a ______ filter.
a. sparkler
b. centrifugal
c. plate and frame
d. rotary drum vacuum
centrifugal
103
Which of the following is a vacuum filter?
a. Filter press
b. Rotary disc filter
c. Batch basket centrifuge
d. Tank filter (Nutsch filter)
Rotary disc filter
104
The unit of specific cake resistance is
a. gm/cm²
b. cm/gm²
c. cm/gm
d. gm/gm²
gm/cm²
105
The unit of filter medium resistance is
a. cm⁻¹
b. cm/gm⁻¹
c. cm/gm
d. gm⁻¹
cm⁻¹
106
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
minimum at the filter medium
107
is defined as a method to keep solid particles floating in an upward direction in a flow of gas or liquid.
Fluidization
108
Equation used to calculate the pressure in fluidization
(-ΔP/L)=(1-ε)(ρp-ρ)g/gc
