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Day 2 - Chemical Engineering Principles > Particle Technology > Flashcards

Particle Technology Flashcards

1
Q

Increasing the capacity of the screen

A

Decreases screen effectiveness

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2
Q

Screen efficiency is

A

recovery x rejection

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3
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

A.

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4
Q

A screen is said to be blinded when

A

the screen is plugged with solid particles

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5
Q

The material passing one screening surface and retained on a subsequent surface is called

A

Intermediate Material

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6
Q

In screen analysis, notation + 5 mm/ -10 mm means passing through
a. 10 mm screen and retained on a 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.

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7
Q

Mesh number indicates the number of holes per

A

Linear inch

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8
Q

Size measurement of ultrafine particles can be best expressed in terms of

A

Surface area/ unit mass

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9
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

C.

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10
Q

Another term for sapphire and ruby

A

Corundum

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11
Q

Units of measurement for coarse particles

A

cm, in, mm

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12
Q

Unit of measurement for fine particles

A

mesh

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13
Q

Unit of measurement for very fine particles

A

microns

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14
Q

Unit of measurement for ultrafine particles

A

cm^2/g

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15
Q

Minerals belonging to the soft category in Moh’s scale of hardness

A

1 - Talc
2 - Gypsum
3 - Calcite

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16
Q

Minerals belonging to the intermediate category in Moh’s scale of hardness

A

4 - Fluorite
5 - Apatite
6 - Feldspar

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17
Q

Minerals belonging to the hard category in Moh’s scale of hardness

A

7 - Quartz
8 - Topaz
9 - Corundum
10 - Diamond

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18
Q

Stages of size reduction

A

Coarse (greater than 2.96 in)
intermediate (1-3 in)
fine (less than 0.5/0.25 in)

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19
Q

Equipment used for coarse materials in size reduction

A

Jaw crusher
Gyratory crusher
Hammer mill

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20
Q

Equipment used for intermediate materials in size reduction

A

Cone crusher
Crushing Rolls

21
Q

Equipment used for fine materials in size reduction

A

Ball mill
Rod mill

22
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.

23
Q

Mechanisms of size reduction

A

Coarse particles - compression
Fine particles - impact
Very fine particles - attrition

24
Q

Size reduction mechanism used in jaw crushers is

A

Compression

25
Q

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

A

D.

26
Q

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

A

B.

27
Q

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

A

C.

28
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.

29
Q

As the product becomes finer, the energy required for grinding

A

Increases

30
Q

The operation by which solids are separated from liquids due to difference in the respective densities

A

Sedimentation

31
Q

Forces acting on a particle settling in a fluid are

A

Gravitational or centrifugal, buoyant and drag forces

32
Q

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

A

A.

33
Q

Stoke’s law is valid when the particle Reynolds number is

A

<1

34
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.

35
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.

36
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.

37
Q

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

A

B.

38
Q

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

A

C.

39
Q

Filtration chapter at Perry’s

A

Chapter 18

40
Q

Filter aid is used to

A

Increase porosity of cake

41
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.

42
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.

43
Q

Screen effectiveness, E formula

A

(check your notes for answer)

44
Q

The formula for capacity (screening)

A

P/F=(Xf-Xr)/(Xp-Xr)

45
Q

The alternate equation for screen effectiveness (E)

A

XpP/XfF (1-((1-Xp)/(1-Xf))(P/F))

46
Q

The driving force behind a free-falling body

A

Gravitational force

47
Q

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

A

A.

48
Q

It is the separation of fluid solid mixture involving the passage of most of the fluid through a porous barrier which retains most of the solid particles contained in the mixture.

A

Filtration

Day 2 - Chemical Engineering Principles (8 decks)

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