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DAY 2 > PARTICLE TECHNOLOGY > Flashcards

PARTICLE TECHNOLOGY Flashcards

1
Q

The equation that is applied to describe the flow of a fluid through a porous medium under laminar condition is
a. Fanning-Darcy Equation
b. Kozeny-Karman Equation
c. Ruth Equation
d. Hagen-Poiseuille Equation

A

b. Kozeny-Karman Equation

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2
Q

The operation by which solids are separated from liquids due to the difference in their respective densities is
a. filtration
b. screening
c. sedimentation
d. adsorption

A

c. sedimentation

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3
Q

In a filtration operation involving incompressible cakes, the flow rate is directly proportional to
a. the viscosity of the filtrate
b. the thickness of the filter cake .
c. the pressure applied
d. the size of the cake particles

A

c. the pressure applied

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4
Q

During filtration of a slurry, the filtration rate will start to fall once the pressure drop across the filter medium
a. begins to rise
b. becomes constant
c. becomes zero
b. begins to fall

A

b. becomes constant

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5
Q

During filtration on a rotary filter the precipitate is continuously removed from he filter medium by a scrapper in order to
a. prevent the precipitate from mixing with the filtrate
b. maintain a constant pressure drop across the filter
c. keep the filter clean
d. none of these

A

c. keep the filter clean

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6
Q

In filtration, the coarser the filtration medium ______ the constant rate period.
a. the shorter
b. the longer
c. does not affect
d. zero

A

b. the longer

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7
Q

In a plate-and-frame filter press, the rate of filtration is directly proportional to the
a. resistance of the filter cake
b. cross-section of the filter surface
c. resistance of the filter medium
d. viscosity of the filtrate

A

b. cross-section of the filter surface

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8
Q
  1. For a non-washing constant pressure filtration where the resistance of the filter medium is negligible, maximum capacity of the filter is attained when the filtration time is
    a. less
    b. equal compared to the dumping and cleaning time.
    c. greater
    d. cannot be determined
A

b. equal compared to the dumping and cleaning time.

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9
Q

If the motion of a particle is impeded by other particles, which will happen when the particles are near each other even though they are not actually colliding, the proses is called
a. gravity settling
b. free settling
c. unhindered settling
d. hindered settling

A

d. hindered settling

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10
Q

The drag coefficient in hindered settling is ____ compared to free settling.
a. constant
b. greater than
c. less than
d. varying

A

b. greater than

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11
Q

The operation by which solids are separated from liquids due to difference in their respective densities is
a. screening
b. sedimentation
c. adsorption
d. absorption

A

b. sedimentation

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12
Q

The separation of solid particles into several size fractions based upon the settling velocities in a medium is called
a. settling
b. filtration
c. flotation
d. classification

A

d. classification

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12
Q

Device in which a current of air separates particles with different sedimentation velocities.
a. agitator
b. air elutriator
c. classifier
d. air conveyor

A

b. air elutriator

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13
Q

The constant velocity with which a body moves relative to the surrounding fluid when the forces acting on it (gravitational or centrifugal or electrostatic forces) are equal to the friction force acting against the motion.
a. terminal velocity
b. settling velocity
c. maximum velocity
d. all of these

A

a. terminal velocity

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14
Q

An apparatus in which particles settle in a liquid by gravitational or centrifugal force and are removed as a concentrated slurry.
a. classifier
b. thickener
c. elutriator
d. agitator

A

b. thickener

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15
Q

In a motion of a particle through fluids, forces act on a particle moving through a fluid. The force which appears whenever there is a relative motion between the particle and the fluid is called
a. gravitational force
b. centrifugal force
c. drag force
d. buoyant force

A

c. drag force

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16
Q

Drag is defined as the force exerted by
a. the fluid on the solid in direction opposite to the motion of the solid
b. the fluid on the solid in the direction of motion of the solid
c. the solid on the fluid
d. none of these

A

a. the fluid on the solid in direction opposite to the motion of the solid

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17
Q

Drag coefficient for flow past an immersed body is the ratio of
a. shear stress to the product of velocity head and density
b. shear force to the product of velocity head and density
c. average drag per unit projected area to the product of the velocity head and density
d. none of these

A

c. average drag per unit projected area to the product of the velocity head and density

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18
Q

Stoke’s Law is valid when the particle Reynolds Number is
a. <1
b. >1
c. <2
d. none of these

A

c. <2

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19
Q

Drag coefficient Cd is given by the Stoke’s Law range
a. Cd = 16/Re,p
b. Cd = 18.4/Re,p
c. Cd = 24/Re,p
d. Cd = 0.079/Re,p^0.23

A

c. Cd = 24/Re,p

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19
Q

At low Reynolds Number
a. viscous forces are unimportant
b. viscous forces equal the inertial forces
c. viscous forces control and inertial forces are unimportant
d. gravity forces control

A

c. viscous forces control and inertial forces are unimportant

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20
Q

At high Reynolds Number
a. inertial forces control and viscous forces are unimportant
b. viscous forces predominate
c. inertial forces are unimportant and viscous forces control
d. none of these

A

a. inertial forces control and viscous forces are unimportant

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21
Q

The ratio of drag force per unit area to the product of fluid density and the velocity head is called
a. buoyant coefficient
b. drag coefficient
c. friction factor
d. shear coefficient

A

b. drag coefficient

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22
Q

In order for a particle to move through a fluid under the influence of gravity, there must be
a. velocity difference
b. pressure difference
c. density difference
d. temperature difference

A

c. density difference

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23
Q

In continuous thickeners, separation of solid particles can be achieved if the settling velocity of the solids is ______ compared to the velocity of the displaced liquid.
a. equal
b. greater
c. less
d. none of these

A

b. greater

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24
Q

For the separation of sugar solution from settled out mud, we use
a. sparkler filter
b. plate and frame filter
c. centrifugal filter
d. rotary drum vacuum filter

A

c. centrifugal filter

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25
Q

Moisture can be removed from lubricating oil using
a. tubular centrifuge
b. clarifier
c. sparkler filter
d. vacuum leaf filter

A

a. tubular centrifuge

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26
Q

Which of the following can be most effectively used for clarification of lube oil and printing ink?
a. sparkler filter
b. disc-bowl centrifuge
c. precoat filter
d. sharpless supercentrifuge

A

d. sharpless supercentrifuge

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27
Q

Where the difference in density of the two liquid phases to be separated is very small (as in milk cream separator), the most suitable separator is
a. disc bond centrifuge
b. batch basket centrifuge
c. sharpless supercentrifuge
d. sparkler filter

A

a. disc bond centrifuge

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28
Q

The material passing one screening surface and retained on a subsequent surface is called
a. intermediate material
b. plus material
c. minus material
d. none of these

A

a. intermediate material

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29
Q

The minimum clear space between the edges of the opening in the screening surface and is usually given in inches or millimeters.
a. sieve
b. mesh number
c. aperture
d. holes

A

c. aperture

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30
Q

The screen used in making size separation smaller than 4-mesh and larger than
48- mesh.
a. grizzly screen
c. oscillating screen
b. gyratory screen
d. vibrating screen

A

d. vibrating screen

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31
Q

When the object is to recover an oversize product from the screen, efficiency may be expressed as

a. ratio of the amount of undersize obtained to the amount of undersize in the feed

b. using the Taggart Formula,
E = 100 (e-v)/e(100-v).100
where:
e = percentage of undersize in the feed;
v = percentage of undersize in the screen oversize

c. ratio of the amount of oversize obtained to the amount of true oversize

d. none of these

A

c. ratio of the amount of oversize obtained to the amount of true oversize

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32
Q

The wire diameter of a 14-mesh screen (Tyler Standard) is
a. 0.0235 in.
b. 0.025 in.
c. 0.028 in.
d. 0.03 in.

A

b. 0.025 in.

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33
Q

Box-like machines, either round or square with a series of screen clothes nested atop one another.
a. reciprocating screen
b. electricity vibrated screen
c. oscillating screen
d. gyratory screen

A

d. gyratory screen

34
Q

The removal of a small amount of oversize from a feed which are predominantly fines is called
a. scalping
b. desliming
c. coarse separation
d. dewatering

A

a. scalping

35
Q

Removal of free water from a solids-water mixture and is generally limited to 4 mesh and above.
a. scalping
b. dewatering
c. trash removal
d. separation

A

b. dewatering

36
Q

Making a size separation smaller than 48-mesh is called
a. coarse separation
b. fine separation
c. ultrafine separation
d. scalping

A

c. ultrafine separation

37
Q

Another name for revolving screen is
a. shaking screen
b. vibrating screen
c. mechanically vibrated screen
d. trommel screen

A

d. trommel screen

38
Q

The mesh number of a screen denotes
a. the area of the screen in square inch
b. the number of openings per linear inch of screen
c. the number of layers in a screen system
d. the number of screens needed to obtain the required fines

A

b. the number of openings per linear inch of screen

39
Q

Materials which remain on a screen surface are called
a. fines
b. undersize
c. Intermediate material
d. oversize

A

d. oversize

40
Q

The Tyler Standard screen series is characterized by
a. square root of two ratio of areas between successive screens
b. square root of four ratio of linear openings between successive screens
c. twice the area ratio between successive screens
d. none of these

A

c. twice the area ratio between successive screens

41
Q

The ratio of the clear opening corresponding to a mesh size in the Tyler Standard screen series to that of the next smaller screen is
а. 2
b. √2
c. 1.5
d. none of these

A

b. √2

42
Q

The clear opening of a 200-mesh screen in the Tyler Standard screen series is
a. 0.0074 cm
c. 0.0047 cm
b. 0.0074 mm
d. 0.0047 mm

A

a. 0.0074 cm

43
Q

The ratio of the area of the opening in one screen (Tyler Series) to the opening of the next smaller screen is
a. 1.5
b. 1
c. √2
d. none of these

A

d. none of these

44
Q

The Cumulative Screen Analysis for determining the surface area of particles is more precise than the differential screen 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

A

c. assumption that all particles in a single fraction are equal in size is not
needed

45
Q

Increasing the capacity of a screen
a. decreases the screen effectiveness
b. increases the screen effectiveness
c. does not affect the screen effectiveness
d. none of these

A

a. decreases the screen effectiveness

46
Q

The screen efficiency is
a. recovery + rejection
b. recovery
c. rejection
d. none of these

A

d. none of these

47
Q

As the 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

a. screening becomes progressively more difficult

48
Q

A screen is said to be blinded when

a. oversize are present in undersize fraction
b. undersize are retained in oversize fraction
c. the screen is plugged with solid particles
d. its capacity is abruptly increased

A

c. the screen is plugged with solid particles

49
Q

Size measurement of ultrafine particles can be best expressed in terms of
a. centimeter
b. screen size
c. micron
d. surface area per unit mass

A

d. surface area per unit mass

50
Q

Trommels separate a mixture of particles depending on their
a. size
b. screen size
c. wettability
d. electrical and magazine

A

a. size

51
Q

Screen capacity is expressed in terms of
a. tons/h
b. tons/ft^2
c. both a and b
d. tons/h-ft^2

A

d. tons/h-ft^2

52
Q

The term applied to all ways in which particles of solids are cut or broken into smaller pieces
c. comminution
a. size reduction
d. crushing
b. screening

A

a. size reduction

53
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?
c. sapphire
a. tale
b. calcite
d. feldspar

A

c. sapphire

54
Q

States that the energy required for crushing is proportional to the new surface created.
a. Rittinger’s Law
b. Kick’s Law
c. Bond Law
d. Energy Law

A

a. Rittinger’s Law

55
Q

In comminution, the energy requirement is determined theoretically by
a. the initial and final sizes of the particles
b. the type of equipment
c. the change in shape of the particle
d. none of these

A

a. the initial and final sizes of the particles

56
Q

Size reduction is important in chemical engineering since
a. it prevents chemical engineers from becoming overweight
b. it makes products to become uniform in size
c. it prepares raw materials of the desired sizes prior to processing
d. none of these

A

c. it prepares raw materials of the desired sizes prior to processing

57
Q

Based on Bond’s Crushing Law, the power required to crush a certain material will change by __ % if the diameter of the product is made smaller by 50%.
a, 50%
b. 41%
c. 25%
d. 75%

A

b. 41%

58
Q

Sphericity for a cylinder whose length equals its diameter is
a. 1.5
b. 0.5
c. 0.87
d. 5

A

c. 0.87

59
Q

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

a. ratio of surface to volume as the actual volume

60
Q

For coarse reduction of hard solids, use
a. impact
b. attrition
c. compression
d. cutting

A

c. compression

60
Q

For coarse reduction of hard solids, use
a. impact
b. attrition
c. compression
d. cutting

A

c. compression

61
Q

Soft and non-abrasive materials can be made into fines by
a. attrition
c. cutting;
b. compression
d. none of these

A

a. attrition

62
Q

Crushing efficiency is the ratio of
a. surface energy created by the 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 the crushing
d. energy absorbed by the solid to the surface energy created by the crushing

A

a. surface energy created by the crushing to the energy absorbed by the solid

63
Q

Rittinger’s Crushing Law states that

a. work required to form a particle of any size is proportional to the square of the surface to volume ratio of the product
b. work required to form a particle of a particular size is proportional to the square root of the surface to volume ratio of the product
c. work required in crushing is proportional to the new surface created
d. for a given machine and feed, crushing efficiency is dependent on the sizes of feed and product

A

c. work required in crushing is proportional to the new surface created

64
Q

Bond Crushing Law

a. calls for relatively less energy for the smaller product particle than does the Rittinger Law
b. less realistic in estimating the power requirements of commercial crushes
c. states that the work required to form particle of any size from very large fed
product
is proportional to the square root of the volume to surface ratio of the
d. states that the work required for the crushing is proportion

A

a. calls for relatively less energy for the smaller product particle than does the Rittinger Law

65
Q

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 a 100 micron screen
b. energy needed to crush one ton of feed to 200 microns
c. energy (kWh/ton of feed) needed to crush small feed to such a size that 80% of product passes a 200-mesh screen
d. energy needed to crush one ton of feed to 100 microns

A

a. gross energy (kWh/ton of feed) needed to reduce very large feed to such a size that 80%

66
Q

The operating speed of a ball mill should be
a. less than the critical speed
b. much more than the critical speed
c. at least equal to the critical speed
d. none of these

A

a. less than the critical speed

67
Q

A fluid energy mill is used for
a. cutting
b. grinding
c. ultragrinding
d. crushing

A

c. ultragrinding

68
Q

Wet grinding in a revolving mill
a. gives less wear on chamber walls than dry grinding
b. requires more energy than for dry grinding
c. increases capacity compared to dry grinding
d. complicates handling of the product compared to dry grinding

A

c. increases capacity compared to dry grinding

69
Q

In screen analysis, notation + 5 mm/ -10 mm means passing through
a. 10 mm screen and retained on 5 mm screen
b. 5 mm screen and retained on 10 mm screen
c. both 5 mm and 13 mm screens
d. neither 5 mm nor 10 mm screens

A

a. 10 mm screen and retained on 5 mm screen

70
Q

For the preliminary breaking of hard rock, we use
a. gyratory crusher
b. tube mill
c. ball mill
d. quirrel-cage disintegrator

A

a. gyratory crusher

71
Q

Size reduction mechanism used in jaw crushers is
a. attribution
b. cutting
c. compression
d. impact

A

c. compression

72
Q

To get ultrafine particles, the equipment used is
a. ball mill
b. rod mill
c. hammer crusher
d. fluid energy mil

A

d. fluid energy mil

73
Q

To get fine talc powder from its granules, the equipment used is
a. roller crusher
b. ball mill
c. jaw crusher
d. gyratory crusher

A

b. ball mill

74
Q

Maximum size reduction in a ball mill is done by
a. attrition
b. compression
c. impact
d. cutting

A

c. impact

75
Q

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

A

a. less than the critical speed

76
Q

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

A

b. inverse of the fluid viscosity

77
Q

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

A

c. depends on the weight of the floating body

78
Q

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

A

a. constant velocity with no acceleration

79
Q

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

A

c. to increase the porosity of the cake

80
Q

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

A

a. minimum at the filter medium

81
Q

Which of the following may prove unsuitable for filtering volatile liquids?
a. pressure filter
b. centrifugal filter
c. gravity filter
d. vacuum filter

A

d. vacuum filter

82
Q

Which is the driving force behind free falling body?
a. centrifugal force
b. electromagnetic force
c. centripetal force
d. gravitational force

A

d. gravitational force

83
Q

Which of the following types of filter are made to operate continuously?
a. rotary drum
b. gravity
c. filter press
d. leaf filter

A

a. rotary drum

DAY 2 (1 decks)

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