1. Particulate materials, powders or bulk solids are used widely in all areas of the
process industries except for:
a) Food Processing
b) Metallurgical
c) Pharmaceutical
d) Detergent
e) Biotechnology
f) Power Generation
g) Oil
h) Chemical
i) Mineral Processing
j) None of these.
2. Some examples of unit operations involving particles and powder except for:
a) Crystallization
b) Precipitation
c) Granulation
d) Spray Drying
e) Leaching
f) Tableting
g) Extrusion
h) Membrane separation
i) Grinding
3. Properties are readily measured, tabulated, or calculated.
a. Gases
b. Liquids
c. Both a & b
d. None of the above
4. Properties depend on the particle size distribution, shape, surface properties,
humidity of the atmosphere, state of compaction of the powder.
a. Particle size
b. Particulate matter
c. Particulate solids
d. None of the above
5. In many powder handling and processing operations ___________ and size
distribution play a key role in determining the bulk properties of the powder.
a. Particle size
b. Particulate matter
c. Particulate solids
d. None of the above
6. __________ is the length of the line which bisects the particle image.
7. ________ is the distance between two tangents on opposite sides of the particle.
8. ________ particle width obtained using an image shearing device.
9. _________ is the area of circle with same area as the projected area of the particle
resting in a stable position.
a. Shear diameter
b. Equivalent circle diameters
c. Feret’s diameter
d. Martin’s diameter
10. The following are quantitative descriptors except for:
a. Elongation
b. Flakiness
c. Aspect Ratio
d. Chunkiness
11. _________ is the surface area of the particle per unit volume
a. Wadell Sphericity
b. Sphericity
c. Specific Surface
d. Both a & b
12. ____________ measures how closely a particle resembles a perfect sphere:
a. Wadell Sphericity
b. Sphericity
c. Specific Surface
d. Both a & b
13. Cube : Tetrahedron , _____:_______ in terms of sphericity.
a. 0.874:0.840
b. 0.840:0.874
c. 0.806:0.671
d. 0.671:0.806
14. Hemisphere : Ideal Cylinder, ______________: ______________
a. 0.874:0.840
b. 0.840:0.874
c. 0.806:0.671
d. 0.671:0.806
15. __________ systems and supplies are normally provided by a large, capable
manufacturing industry, which holds much of the engineering information in form of
brochures, data sheets, and nomographs.
a. Conveying
b. Grinding and cutting
c. Size Reduction
d. Screening
16. It may be used to create particles of a certain size and shape, to increase surface
area available for chemical reaction
17. A method of separating solid particles according to size alone is called ________.
18. In the __________process, materials are reduced in size by fracturing them.
19. It refers to the separation of solid materials based on size using screens of known
openings.
20. ________ or comminution is an important step in the processing of many solid
materials
21. _________ reduce the size of solid materials by mechanical action, dividing them
into smaller particles.
22. _________is commonly adopted for dry particulate solids and occasionally for wet
particulate solids.
23. Materials for Screens are given below except for
a. woven wire cloth
b. grizzlies
c. silk bolting cloth
d. slotted metal plates
24. The _________on a body in N may be derived from the fact that, as in flow of fluids,
the __________ or frictional resistance is proportional to the velocity head v 2/2 of the
fluid displaced by the moving body. This must be multiplied by the density of the
fluid and by a significant area A, such as the projected area of the particle
a. Spherical particles
b. Drag Coefficient
c. Drag force
d. Wall effect
25. When the diameter Dp of the particle becomes appreciable with respect to the
diameter Dw of the container in which the settling is occurring, a retarding effect
known as the __________ is exerted on the particle.
26. The _____________ for rigid spheres has been shown to be a function of the Reynolds
number Dpvρ/µ of the sphere.
27. The ___________ based on the oversize material is the ratio of the amount of oversize
material that is actually in the overflow to the amount of oversize material in the
feed.
a. size enlargement
b. effective viscosity
c. screen effectiveness
d. none of these
28. Processes involving any kind of _____________ receive diverse denominations
including compaction, granulation, encapsulation, pelletizing, agglomeration, and
sintering.
29. The higher________ of the mixture µm is equal to the actual viscosity of the liquid
itself, µ, divided by an empirical correction factor, Ψp, which depends upon ε, the
volume fraction of the slurry mixture occupied by the liquid.
30. Equipment for Particle Size Reduction except for
a. Jaw Crushers
b. Gyratory Crushers
c. Roll Crushers
d. Grizzlies
e. Trommels
f. Hammer Mill Grinders
g. Revolving Grinding Mills
31. The factors which tend to reduce the capacity and lower effectiveness are:
i. Blinding
ii. Cohesion
iii. Screening surfaces
iv. Moisture content of the feed
v. Screen Slope
vi. Motion or speed of the screen
vii. Vibration and Frequency
a. i, iii, iv & vi
b. ii, v, vi, & vii
c. i, ii, iv, &vi
d. i, iii, v, & vii
32. Importance of Screening Operations except for:
i. Remove the fines from a feed material before an enlargement
equipment such as Jaw crusher, Ball Mill or Rod Mill
ii. Prevent a completely crushed material (oversize) from entering into
other unit operations.
iii.
Produce a commercial or process grade material to meet specific
particle size limits.
Remove the fines from a finished product prior to shipping.
iv.
a. i & iii only
b. ii & iv only
c. i & ii only
d. iii & iv only
33. Screening Equipment except:
a. Grizzlies
b. Trommels
c. Gyratory Screens
d. Vibrating Screens
34. Fed the material properly, Spread the material evenly over a full width of the
screening surface, Must fed at low flow rate.
a. Screening surfaces
b. Screen Slope
c. Vibration and Frequency
d. Method of Feeding
35. Depends on speed and amplitude of vibration for best performance
36. Depends on slope of the screen however slope cannot be increased beyond a
certain value because beyond that value material will travel down the screen much
faster without getting screened and the screening efficiency reduces drastically.
37. One has to select proper amplitude and vibration to prevent blinding of the
screening cloth and for long bearing life. The frequency of vibration affects the
capacity of the screening equipment by regulating the number of contacts between
the material and the screening surface.
38. The testing sieves with square opening are constructed of _________, the mesh and
dimensions of which are standardized.
a. Fine screens
b. Coarse screens
c. Screen aperture
d. Woven wire screens
39. In _________, the term mesh refers to the distance between adjacent wires or rods.
40. While in _________, the mesh is the number of openings per linear inch counting
from the center of any wire to a point exactly one inch distance.
41. The minimum clear space between the edges of the opening in the screening
surface is termed as _____________ or screen size opening.
42. The fine particles are generally specified according to their _________.
a. Cumulative analysis
b. Differential analysis
c. Capacity
d. Screen analysis
43. A __________ of a material is carried out by using testing sieves.
44. An analysis reported in a tabular form in this manner is called a _________.
45. The ________ is obtained from the differential analysis by adding, the individual
weight fractions of material retained on each screen, starting with that retained on
the largest mesh.
46. ___________: The screen analysis in which the weight fraction of the material
retained on each screen is reported in tabular or graphical form as a function of the
mesh size/screen opening.
47. The _________ of a screen is the mass of material that can be fed per unit time to a
unit area of the screen.
48. In (1867) someone proposed a law that states that the work in crushing is
proportional to the new surface created. Since area is proportional to the length
squared, Used for grinding fine powders.
a. Bond’s Law
b. Rittinger’s Law
c. Kick’s Law
d. None of the above
49. Friedrich(1885) assumed that the energy required to reduce a material in size was
directly proportional to the size reduction ratio (n=1):
50. Fred(1952) suggest that the work required using a large-size feed (X1≈0) is
proportional to the square root of the surface/volume ratio of the product (n=1.5):
51. The number of interaction sites of each particle within the agglomerate is known as
________.
a. Agglomerate
b. Coalescence
c. Solid particle
d. Coordination number
52. It occurs at the contact point when, at impact, a binding mechanism develops
which is stronger than the separating forces.
53. Additional growth of the _________ may proceed by further coalescence, or by
layering, or both.
54. The most important and effective separation force counteracting on the bonding
mechanism is the weight of the _________.
55. In __________ pressure forces act on a confined mass of particulate solids, which is
then shaped and densified.
a. Agglomeration
b. Tumbling agglomeration
c. Pressure agglomeration
d. None of the above
56. It may be defined as the process of bonding individual particles in a random way, in
order to end with an aggregate considerably larger in size and with a porous
structure
57. In the food industry, __________ is used in the food processing to improve
reconstitutability of several products including flours, cocoa powder, instant
coffee, dried milk, sugar, sweeteners, fruit beverages powders, instant soups, and
diverse spices.
58. __________, also termed “nonsuspension” conveying, is normally used to discharge
particulate solids or to move materials over short distances.
Free settling velocity
a.
b. Dilute-phase conveying
c. Dense-phase conveying
Terminal velocity
d.
59. __________, or dispersed-phase conveyors, are more versatile in use and can be
considered the typical pneumatic conveying systems as described in the literature.
60. The initial acceleration is very short. So, the period of constant-velocity fall is the
important one. It is called the________.
61. There are several types of nonsuspension conveying equipment except for one:
a. plug-phase conveyors
b. fluidized systems
c. closed-loop system
d. blow tanks
62. The most accepted classification of dilute-phase conveyors comprises:
a. pressure
b. long-distance systems
c. vacuum
d. none of the above
63. These systems are used to handle finely divided powders, damp materials, hot
substances that may be chemically active, as well as granular materials of all types.
a. Belt conveyer
b. Bucket elevator
c. Pnuematic Conveyor
d. Screw Conveyor
64. This type of conveying comprises high-capacity units primarily intended for bulk
elevation of relatively free-flowing materials and may be considered a special
adaptation of chain conveying.
65. The horsepower P required to drive a _____________ depends on the dimensions of
the system and the characteristics of the material.
66. The _______________ consists, essentially, of an endless belt operating between two
or more pulleys, friction driven at one end and carried on an idler drum at the
opposite end.
67. ___________ are also used for batch or continuous mixing, for feeding where a fairly
accurate rate is required, and for conventional conveying, as well as elevating
duties, particularly if the run is short.
68. ____________are the simplest and most dependable equipment units for vertical
lifting of different types of granular materials.
69. _________ are used for movement of different types of bulk solids at distances
varying from meters to kilometers and, thus, its load have to be supported on idlers
on both conveying and return sections.
70. They are available in a wide range of capacities and may operate either in the entire
open or be totally enclosed.
II. Matching Type
Shape
a. Cone
b. Cube
c. Cuboid
d. Cylinder
e. Sphere
Dimension
a. Radius Side
b. Length
c. Radius and height
d. Three sides lengths
e. Radius and height
II. Which statement is true?
a. 1st statement is true
b. 2nd statement is true
c. Each statement is true
d. Each statement is false
1. A regular-shaped particle’s size cannot be described by a single physical
dimension. This will depend on two things: (a) what property or dimension of the
particle we are able to measure and (b) the use to which the dimension is to be put.
2. A collection of particles always shows a PSD, since there are always some
deviations during their accumulation or production. Sometimes, these deviations
are large and all particles have nearly the same size.
3. The material that passes through a given screen/screening surface is called the
undersize or plus (+) material while the material that remains on the
screen/screening surface is called the oversize or minus (-) material.
4. In screening, a mixture of solid particles of various sizes is dropped on a screening
surface/screen (a surface provided with suitable openings) which acts as multiple
go and no go gage. Solids may be separated from solids (according to size) in the
dry state by methods such as size reduction, magnetic separation and electrostatic
separation.
5. A single screen can make a single separation of the material charged into three
fractions. These are called unsized fractions as only the upper limit or lower limit of
the particle sizes they contain is known and the other limit is not known.
6. The material can’t be separated into sized fractions in which both the maximum and
minimum particle sizes are known, by passing it through a series of screens of
different sizes. As the particles retained on any one screen are passed through the
screen immediately above it, three numbers are needed to specify the size, one for
the screen through which the fraction passes and the other for the screen on which
that fraction retained.
7. For obtaining maximum effectiveness the capacity must be large and vice versa.
Hence, the notation 10/14 means through 14 mesh and on 10 mesh.
8. Size reduction of solids is an energy intensive and highly inefficient process. Design
and scale-up of comminution processes is usually based on experience and testing
9. The force applied may be compression, impact, or shear, and both the magnitude of
the force and the time of application affect the extent of grinding achieved. The
important factors to be studied in the grinding process are the amount of energy
used and the amount of new surface formed by grinding.
10. Each particle interacts with neighboring particles, while points of interaction may
be kept together by physical contact or by attractive forces due to the proximity of
such points. Indirect measurement of the coordination number can be made as a
function of other properties of the agglomerate.
11. The moisture associated with feed material adversely affects the screening
operation and should not be removed. For particles below 10 μm approximately,
the natural attraction forces, such as molecular, magnetic, and electrostatic,
become significantly smaller than the separation forces due to particle mass and
external influences.
12. The average size of the particle retained on any particular screen is calculated as
the geometric mean of two screen openings used to obtain the fraction. A set of
standard screens is arranged serially in a stack in such way that the coarsest of the
screens is at the top and the finest of the screens is at the bottom.
13. The analysis is carried out by placing the sample on the top screen and shaking the
stack in a definite manner, either manually or mechanically for a definite length of
the time. The material remained in each screen is removed and weighed.
14. For reporting the screen analysis, the amount of material retained on each screen is
expressed as the weight fraction of the total sample as a function of the mesh size.
The screen analysis of a sample is reported either in a tabular form or graphs.
15. As the capacity and effectiveness are opposing factors, a reasonable balance must
be done between them in actual practice. Every screen is identified in meshes per
foot.
16. In general terms, any equipment or environment creating random movement is
suitable for carrying out tumbling agglomeration. In certain applications, very
simple tumbling motions, such as on the slope of storage piles or on other inclined
surfaces, are sufficient for the formation of crude agglomerates
17. Pressure agglomeration is normally carried out in two stages. The first one
comprises a force rearrangement of particles due to a little applied pressure while a
second step consists on a steep pressure rise during which brittle particles break
and malleable particles deform plastically.
18. For such hindered flow, the settling velocity is less than would be calculated from
the Stokes’ law equation. The true drag force is less than in the suspension because
of the interference of the other particles
19. The elements comprising a pneumatic conveying system are: the belt, a drive
system, some tension elements, the idlers, and appropriate loading and discharge
devices. Belts must not be flexible enough to conform to the pulleys, wide enough
to carry the quantity and type of material required, have sufficient strength to stand
up under the expected load and operating tension, and posses a resistant surface.
20. One of the most important bulk solids handling techniques in a solids handling
plant is the movement of material suspended in a stream of air over horizontal,
inclined or vertical surfaces, ranging from a few to several hundred meters. One of
the earliest recorded uses of pneumatic conveying was for unloading wheat from
barges to flour mills at the end of the nineteenth century in Europe.