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Particle Technology Flashcards

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1
Q

Kick’s law is best suited for:
A. Fine grinding
B. Small particle sizes
C. Large particle sizes
D. Ultrafine particles

A

b

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2
Q

Rittinger’s law states that energy required is proportional to the increase in:
A. Volume
B. Surface area
C. Mass
D. Density

A

b

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3
Q

Bond’s law gives more accurate results in:
A. Coarse crushing
B. Intermediate grinding
C. Ultrafine milling
D. Size enlargement

A

a

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4
Q

Which of the following expresses energy per unit mass for crushing?
A. Reynolds number
B. Bond Work Index
C. Froude number
D. Peclet number

A

c

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5
Q

Kick’s law assumes constant energy per unit volume reduction.
A. True
B. False

A

a

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6
Q

Critical speed of a ball mill is the speed at which:
A. Balls begin to centrifuge
B. Maximum impact occurs
C. Frictional losses are minimized
D. Load is balanced

A

c

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7
Q

A hammer mill operates primarily through:
A. Compression
B. Impact
C. Attrition
D. Cutting

A

b

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8
Q

A rod mill is preferred over a ball mill when:
A. Very fine grinding is needed
B. Coarse grinding is needed
C. Ultra-precise milling is required
D. Powder mixing is needed

A

b

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9
Q

Reduction ratio is defined as:
A. Product size/Feed size
B. Feed size/Product size
C. Screen area/Feed rate
D. Motor power/Product size

A

b

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10
Q

Ball mills are typically used for ultrafine grinding.
A. True
B. False

A

b

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11
Q

Which mill has a cascading and cataracting motion of balls?
A. Ball mill
B. Fluid energy mill
C. Hammer mill
D. Edge runner mill

A

a

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12
Q

The most common industrial comminution laws are:
A. Arrhenius, Antoine, Henry
B. Kick, Rittinger, Bond
C. Pascal, Newton, Raoult
D. Euler, Bernoulli, Newton

A

b

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13
Q

A fluid energy mill is used for:
A. Drying
B. Coarse grinding
C. Ultra-fine grinding
D. Dewatering

A

c

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14
Q

In a crushing operation, if the energy required is directly proportional to the size reduction ratio, which law applies?
A. Rittinger
B. Bond
C. Kick
D. None of the above

A

c

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15
Q

The term “critical speed” in a ball mill refers to:
A. Maximum throughput
B. Speed at which grinding stops
C. Speed at which centrifugal force equals gravitational force
D. Design safety speed

A

c

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16
Q

True or False: Kick’s law is applicable for small particle sizes.
A. True
B. False

A

b

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17
Q

Which size reduction device operates best for fibrous materials?
A. Roller mill
B. Cutter mill
C. Jaw crusher
D. Ball mill

A

b

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18
Q

Attrition involves:
A. Cutting
B. Shearing
C. Frictional rubbing
D. Impact

A

c

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19
Q

Which mill is most suitable for brittle materials?
A. Ball mill
B. Hammer mill
C. Rod mill
D. Jet mill

A

b

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20
Q

True or False: Energy required for grinding increases with decreasing particle size.
A. True
B. False

A

a

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21
Q

Screening separates particles by:
A. Shape
B. Size
C. Color
D. Charge

A

b

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22
Q

A screen labeled “100 mesh” has:
A. 100 holes per square inch
B. 100 mm openings
C. 100 holes per linear inch
D. 10 mm apertures

A

c

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23
Q

As mesh number increases:
A. Aperture size increases
B. Particle size increases
C. Aperture size decreases
D. Screen becomes coarser

A

c

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24
Q

Gyratory screens move in a circular path.
A. True
B. False

A

a

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24
Trommel screens are typically used for: A. Fine screening B. Coarse screening C. Air classification D. Drying
b
25
Screen efficiency is defined as: A. % of oversize removed B. % of undersize passing through C. Feed rate per screen area D. Product yield per unit energy
b
26
Blinding refers to: A. Mesh wear B. Hole clogging C. Incorrect mesh size D. Overloading
b
27
Wet screening reduces blinding compared to dry screening. A. True B. False
a
28
A vibrating screen is used for: A. Mixing B. Size reduction C. Separation by density D. Particle size separation
d
29
Gyratory screens use what motion? A. Linear B. Circular C. Angular D. Oscillating
b
30
Sedimentation involves separation of solids from liquid by: A. Diffusion B. Flotation C. Settling under gravity D. Electrostatics
c
31
Stokes’ Law applies when flow is: A. Turbulent B. Transitional C. Laminar D. Mixed
c
32
Terminal settling velocity increases with: A. Increasing fluid viscosity B. Increasing particle diameter C. Decreasing particle density D. Decreasing gravity
b
33
A smaller particle settles faster than a larger particle. A. True B. False
b
34
The drag coefficient in Stokes' law is: A. Independent of particle shape B. Constant for all velocities C. Valid only for laminar flow D. Dependent on turbulence
c
35
Free settling occurs when: A. Particles settle independently B. Concentration is high C. Inter-particle effects dominate D. Viscosity is negligible
a
36
Hindered settling occurs in: A. Very dilute systems B. High solid concentration C. Centrifuges D. Low-density systems
b
37
Clarifiers are used to: A. Filter solids B. Remove dissolved gases C. Separate solid-liquid mixtures by settling D. Grind solids
c
38
Thickeners are primarily designed to: A. Remove moisture B. Concentrate slurries C. Separate gases D. Increase pH
b
39
Hindered settling velocity is always greater than free settling velocity. A. True B. False
b
40
Stoke’s Law neglects: A. Fluid drag B. Buoyancy C. Inertia D. Gravitational force
c
41
In a continuous thickener, the underflow contains: A. Clarified liquid B. Diluted slurry C. Concentrated solids D. Gases
c
42
Elutriation separates particles based on: A. Shape B. Color C. Terminal velocity D. Surface area
c
43
In sedimentation, particle density affects settling rate. A. True B. False
a
44
The Reynolds number in sedimentation is based on: A. Fluid density B. Settling velocity C. Particle diameter D. All of the above
d
45
The design of settling tanks is primarily based on: A. Reynolds number B. Surface overflow rate C. Sludge recirculation ratio D. Tank height
b
46
Lamella settlers increase settling efficiency by: A. Increasing tank diameter B. Adding chemicals C. Increasing settling area via inclined plates D. Decreasing overflow rate
c
47
In sedimentation, flocculation helps to: A. Reduce settling rate B. Increase particle density C. Increase particle size D. Decrease fluid viscosity
c
48
A hindered settling classifier separates particles by: A. Size only B. Velocity only C. Density only D. Both size and density
d
49
In flocculated systems, particles settle faster than in dispersed systems. A. True B. False
a
50
Which of the following equipment uses centrifugal force for separation? A. Gravity settler B. Clarifier C. Cyclone D. Thickener
c
51
In a cyclone separator, the cut size is influenced by: A. Feed rate B. Vortex finder diameter C. Cyclone diameter D. All of the above
d
52
Which of the following is not typically used in solid-liquid separation? A. Filter press B. Gravity thickener C. Centrifuge D. Ball mill
d
53
The term "cut size" in classification refers to: A. Average feed size B. Size below which 50% of particles report to overflow C. Particle size retained by the screen D. Size at which classification stops
b
54
Cyclones are typically more efficient at separating larger particles than finer ones. A. True B. False
a
55
Which of the following classifiers relies on upward flow of liquid? A. Rake classifier B. Spiral classifier C. Elutriator D. Vibrating classifier
a
56
An elutriation tank separates particles based on: A. Magnetic susceptibility B. Terminal velocity C. Solubility D. Friction
b
57
A classifier that uses a spiraling motion can handle continuous operation. A. True B. False
a
58
In sedimentation, increasing particle size generally: A. Slows settling B. Has no effect C. Increases settling rate D. Causes particles to float
c
59
Which force dominates in Stokesian sedimentation? A. Inertial force B. Centrifugal force C. Viscous drag D. Electrical force
c
60
In continuous thickeners, overflow is rich in solids. A. True B. False
b
61
In a countercurrent decantation system: A. Solids and liquids move in same direction B. Liquid moves opposite to solids C. Only solids are removed D. Solids are recycled
b
62
For particles to settle individually in sedimentation, the suspension must be: A. Saturated B. Turbulent C. Dilute D. Concentrated
c
63
Drag force increases with velocity in laminar settling. A. True B. False
a
64
A cyclone operates primarily on: A. Electrostatic attraction B. Settling under gravity C. Density difference and centrifugal force D. Magnetic separation
c
65
As mesh number increases, the screen opening size increases. A. True B. False
b
66
Which type of screen moves in a circular path? A. Vibrating screen B. Gyratory screen C. Trommel D. Shaking screen
a
67
The efficiency of a screen is the measure of: A. Energy consumption B. Power required C. Correct separation of fines and coarse D. Mesh count
c
68
Blinding in screening refers to: A. Excessive vibration B. Large mesh openings C. Clogging of screen holes D. Misalignment
c
69
Trommel screens are more suitable for coarse screening. A. True B. False
a
70
The open area of a screen affects: A. Strength B. Efficiency C. Thickness D. Motor size
b
71
In dry screening, screen capacity generally increases with: A. Humidity B. Feed moisture C. Finer particles D. Larger screen openings
d
72
Which equipment uses rotational motion for screening? A. Vibrating screen B. Trommel C. Centrifuge D. Cone classifier
Trommel
73
Sedimentation is a process of separation based on: A. Viscosity B. Density difference C. Solubility D. Surface area
b
74
Stokes’ Law applies to particles settling in: A. Turbulent flow B. Laminar flow C. Compressed air D. Packed beds
b
75
Smaller particles settle faster than larger particles. A. True B. False
b
76
The terminal velocity of a particle in a fluid depends on: A. Density difference B. Viscosity C. Particle diameter D. All of the above
d
77
A clarifier is designed to: A. Heat liquids B. Separate immiscible liquids C. Settle suspended solids D. Filter solids
c
78
In sedimentation, hindered settling occurs when: A. Particles are isolated B. High concentration of particles exists C. Particles float D. Air bubbles interfere
b
79
In sedimentation, particle shape has no effect on settling velocity. A. True B. False
b
80
A thickener is used to: A. Remove fines B. Dilute solids C. Concentrate slurry D. Filter air
c
81
Free settling occurs when: A. No particle interactions B. High slurry concentration C. Low settling velocity D. Agglomeration occurs
a
82
Which law is used to calculate settling velocity in low Reynolds number? A. Bernoulli’s B. Newton’s C. Stokes’ D. Fanning’s
c
83
Which of the following size reduction methods primarily utilizes compression forces? a) Ball mill b) Jaw crusher c) Hammer mill d) Fluid energy mill
b
84
The efficiency of a cyclone separator is generally increased by: a) Decreasing the inlet gas velocity b) Increasing the particle density c) Increasing the cyclone diameter d) Decreasing the gas viscosity
b
85
In filtration, the resistance to flow is primarily due to: a) The pump head b) The viscosity of the filtrate c) The filter medium and the accumulated cake d) The pressure drop across the system
c
86
Which of the following is a common method for particle size enlargement? a) Attrition b) Comminution c) Agglomeration d) Sieving
c
87
The angle of repose of a powder is related to its: a) Particle density b) Moisture content c) Flowability d) Particle size distribution
c
88
Which type of mixer is best suited for blending cohesive powders? a) Ribbon blender b) Double cone blender c) Fluidized bed mixer d) Pug mill
d
89
What is the Sauter mean diameter (d 32)? a) The arithmetic mean of the particle diameters b) The diameter of a sphere having the same volume as the particle c) The diameter of a sphere having the same surface area per unit volume as the particle d) The mass mean diameter
c
90
Which type of mill utilizes high-velocity impact of particles against each other for size reduction? a) Rod mill b) Ball mill c) Jet mill d) Roll crusher
c
91
What is the primary purpose of fluidization in particle technology? a) To separate particles by size b) To enhance heat and mass transfer c) To reduce particle attrition d) To compact powders
b
92
Which of the following is a dimensionless number that characterizes the flow regime of a fluid-particle system? a) Reynolds number b) Nusselt number c) Sherwood number d) Peclet number
a
93
Which of the following is a common method for measuring the surface area of a powder? a) Sieve analysis b) X-ray diffraction c) BET adsorption d) Optical microscopy
c
94
What is the primary mechanism of particle collection in a fabric filter (baghouse)? a) Inertial impaction b) Electrostatic attraction c) Sieving and interception d) Gravitational settling
c
95
Which of the following factors does NOT significantly affect the minimum fluidization velocity? a) Particle size and shape b) Fluid viscosity and density c) Reactor vessel material d) Particle density
c
96
What is the primary advantage of using a fluidized bed reactor for solid-catalyzed gas-phase reactions? a) Low heat transfer rates b) Poor gas-solid contact c) Uniform temperature distribution d) High pressure drop
c
97
Which of the following is a common type of impeller used for suspending solids in a stirred tank? a) Centrifugal pump impeller b) Turbine impeller c) Propeller for liquids d) Axial compressor blades
b
98
The angle of internal friction of a powder is a measure of its: a) Compressibility b) Adhesiveness c) Shear strength d) Bulk density
c
99
Which type of dryer is best suited for drying heat-sensitive particulate materials? a) Rotary dryer b) Fluidized bed dryer c) Spray dryer d) Tunnel dryer
c

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